Changeset 73467 in vbox for trunk/src/VBox/Devices

Timestamp:

Aug 3, 2018 9:49:55 AM (7 years ago)

Author:

vboxsync

svn:sync-xref-src-repo-rev:

124094

Message:

DrvAudio: Cleaned up the internal stream organization by not duplicating stuff like the status and the like by having two PDMAUDIOSTREAMs (on for the guest side and one for the host side). Instead, only use PDMAUDIOSTREAM and keep the guest and host specifics in PDMAUDIOSTREAMCTX. Should help simplifying things a lot.

Location:

trunk/src/VBox/Devices/Audio

Files:

• DrvAudio.cpp (modified) (113 diffs)
• DrvAudio.h (modified) (1 diff)

trunk/src/VBox/Devices/Audio/DrvAudio.cpp

@@ -48 +48 @@
 static int drvAudioStreamControlInternalBackend(PDRVAUDIO pThis, PPDMAUDIOSTREAM pStream, PDMAUDIOSTREAMCMD enmStreamCmd);
 static int drvAudioStreamControlInternal(PDRVAUDIO pThis, PPDMAUDIOSTREAM pStream, PDMAUDIOSTREAMCMD enmStreamCmd);
-static int drvAudioStreamCreateInternalBackend(PDRVAUDIO pThis, PPDMAUDIOSTREAM pHstStream, PPDMAUDIOSTREAMCFG pCfgReq, PPDMAUDIOSTREAMCFG pCfgAcq);
-static int drvAudioStreamDestroyInternalBackend(PDRVAUDIO pThis, PPDMAUDIOSTREAM pHstStream);
+static int drvAudioStreamCreateInternalBackend(PDRVAUDIO pThis, PPDMAUDIOSTREAM pStream, PPDMAUDIOSTREAMCFG pCfgReq, PPDMAUDIOSTREAMCFG pCfgAcq);
+static int drvAudioStreamDestroyInternalBackend(PDRVAUDIO pThis, PPDMAUDIOSTREAM pStream);
 static void drvAudioStreamFree(PPDMAUDIOSTREAM pStream);
 static int drvAudioStreamUninitInternal(PDRVAUDIO pThis, PPDMAUDIOSTREAM pStream);
@@ -55 +55 @@
 static int drvAudioStreamIterateInternal(PDRVAUDIO pThis, PPDMAUDIOSTREAM pStream);
 static int drvAudioStreamReInitInternal(PDRVAUDIO pThis, PPDMAUDIOSTREAM pStream);
-static int drvAudioStreamLinkToInternal(PPDMAUDIOSTREAM pStream, PPDMAUDIOSTREAM pPair);
+static void drvAudioStreamResetInternal(PDRVAUDIO pThis, PPDMAUDIOSTREAM pStream);
 
 #ifndef VBOX_AUDIO_TESTCASE
@@ -191 +191 @@
 #endif /* defined(VBOX_STRICT) || defined(LOG_ENABLED) */
 
-/**
- * Returns the host stream part of an audio stream pair, or NULL
- * if no host stream has been assigned / is not available.
- *
- * @returns IPRT status code.
- * @param   pStream             Audio stream to retrieve host stream part for.
- */
-DECLINLINE(PPDMAUDIOSTREAM) drvAudioGetHostStream(PPDMAUDIOSTREAM pStream)
-{
-    AssertPtrReturn(pStream, NULL);
-
-    if (!pStream)
-        return NULL;
-
-    PPDMAUDIOSTREAM pHstStream = pStream->enmCtx == PDMAUDIOSTREAMCTX_HOST
-                               ? pStream
-                               : pStream->pPair;
-    if (pHstStream)
-    {
-        AssertReleaseMsg(pHstStream->enmCtx == PDMAUDIOSTREAMCTX_HOST,
-                         ("Stream '%s' resolved as host part is not marked as such (enmCtx=%RU32)\n",
-                          pHstStream->szName, pHstStream->enmCtx));
-
-        AssertReleaseMsg(pHstStream->pPair != NULL,
-                         ("Stream '%s' resolved as host part has no guest part (anymore)\n", pHstStream->szName));
-    }
-    else
-        LogRel(("Audio: Warning: Stream '%s' does not have a host stream (anymore)\n", pStream->szName));
-
-    return pHstStream;
-}
-
 # if 0 /* unused */
 static int drvAudioProcessOptions(PCFGMNODE pCfgHandle, const char *pszPrefix, audio_option *paOpts, size_t cOpts)
@@ -361 +329 @@
     LogFunc(("[%s] enmStreamCmd=%s\n", pStream->szName, DrvAudioHlpStreamCmdToStr(enmStreamCmd)));
 
-    PPDMAUDIOSTREAM pHstStream = drvAudioGetHostStream(pStream);
-    PPDMAUDIOSTREAM pGstStream = pHstStream ? pHstStream->pPair : pStream;
-    AssertPtr(pGstStream);
-
 #ifdef LOG_ENABLED
-    char *pszHstSts = dbgAudioStreamStatusToStr(pHstStream->fStatus);
-    char *pszGstSts = dbgAudioStreamStatusToStr(pHstStream->fStatus);
-    LogFlowFunc(("Status host=%s, guest=%s\n", pszHstSts, pszGstSts));
-    RTStrFree(pszGstSts);
-    RTStrFree(pszHstSts);
+    char *pszStreamSts = dbgAudioStreamStatusToStr(pStream->fStatus);
+    LogFlowFunc(("fStatus=%s\n", pszStreamSts));
+    RTStrFree(pszStreamSts);
 #endif /* LOG_ENABLED */
 
@@ -379 +341 @@
         case PDMAUDIOSTREAMCMD_ENABLE:
         {
-            if (!(pGstStream->fStatus & PDMAUDIOSTREAMSTS_FLAG_ENABLED))
+            if (!(pStream->fStatus & PDMAUDIOSTREAMSTS_FLAG_ENABLED))
             {
-                if (pHstStream)
-                {
-                    /* Is a pending disable outstanding? Then disable first. */
-                    if (pHstStream->fStatus & PDMAUDIOSTREAMSTS_FLAG_PENDING_DISABLE)
-                        rc = drvAudioStreamControlInternalBackend(pThis, pHstStream, PDMAUDIOSTREAMCMD_DISABLE);
-
-                    if (RT_SUCCESS(rc))
-                        rc = drvAudioStreamControlInternalBackend(pThis, pHstStream, PDMAUDIOSTREAMCMD_ENABLE);
-                }
+                /* Is a pending disable outstanding? Then disable first. */
+                if (pStream->fStatus & PDMAUDIOSTREAMSTS_FLAG_PENDING_DISABLE)
+                    rc = drvAudioStreamControlInternalBackend(pThis, pStream, PDMAUDIOSTREAMCMD_DISABLE);
 
                 if (RT_SUCCESS(rc))
-                    pGstStream->fStatus |= PDMAUDIOSTREAMSTS_FLAG_ENABLED;
+                    rc = drvAudioStreamControlInternalBackend(pThis, pStream, PDMAUDIOSTREAMCMD_ENABLE);
+
+                if (RT_SUCCESS(rc))
+                    pStream->fStatus |= PDMAUDIOSTREAMSTS_FLAG_ENABLED;
             }
             break;
@@ -399 +358 @@
         case PDMAUDIOSTREAMCMD_DISABLE:
         {
-            if (pGstStream->fStatus & PDMAUDIOSTREAMSTS_FLAG_ENABLED)
+            if (pStream->fStatus & PDMAUDIOSTREAMSTS_FLAG_ENABLED)
             {
-                if (pHstStream)
+                /*
+                 * For playback (output) streams first mark the host stream as pending disable,
+                 * so that the rest of the remaining audio data will be played first before
+                 * closing the stream.
+                 */
+                if (pStream->enmDir == PDMAUDIODIR_OUT)
                 {
-                    /*
-                     * For playback (output) streams first mark the host stream as pending disable,
-                     * so that the rest of the remaining audio data will be played first before
-                     * closing the stream.
-                     */
-                    if (pHstStream->enmDir == PDMAUDIODIR_OUT)
-                    {
-                        LogFunc(("[%s] Pending disable/pause\n", pHstStream->szName));
-                        pHstStream->fStatus |= PDMAUDIOSTREAMSTS_FLAG_PENDING_DISABLE;
-                    }
-
-                    /* Can we close the host stream as well (not in pending disable mode)? */
-                    if (!(pHstStream->fStatus & PDMAUDIOSTREAMSTS_FLAG_PENDING_DISABLE))
-                        rc = drvAudioStreamControlInternalBackend(pThis, pHstStream, PDMAUDIOSTREAMCMD_DISABLE);
+                    LogFunc(("[%s] Pending disable/pause\n", pStream->szName));
+                    pStream->fStatus |= PDMAUDIOSTREAMSTS_FLAG_PENDING_DISABLE;
                 }
 
-                if (RT_SUCCESS(rc))
-                    pGstStream->fStatus &= ~PDMAUDIOSTREAMSTS_FLAG_ENABLED;
+                /* Can we close the host stream as well (not in pending disable mode)? */
+                if (!(pStream->fStatus & PDMAUDIOSTREAMSTS_FLAG_PENDING_DISABLE))
+                {
+                    rc = drvAudioStreamControlInternalBackend(pThis, pStream, PDMAUDIOSTREAMCMD_DISABLE);
+                    if (RT_SUCCESS(rc))
+                        pStream->fStatus &= ~PDMAUDIOSTREAMSTS_FLAG_ENABLED;
+                }
             }
             break;
@@ -427 +384 @@
         case PDMAUDIOSTREAMCMD_PAUSE:
         {
-            if (!(pGstStream->fStatus & PDMAUDIOSTREAMSTS_FLAG_PAUSED))
+            if (!(pStream->fStatus & PDMAUDIOSTREAMSTS_FLAG_PAUSED))
             {
-                if (pHstStream)
-                    rc = drvAudioStreamControlInternalBackend(pThis, pHstStream, PDMAUDIOSTREAMCMD_PAUSE);
-
+                rc = drvAudioStreamControlInternalBackend(pThis, pStream, PDMAUDIOSTREAMCMD_PAUSE);
                 if (RT_SUCCESS(rc))
-                    pGstStream->fStatus |= PDMAUDIOSTREAMSTS_FLAG_PAUSED;
+                    pStream->fStatus |= PDMAUDIOSTREAMSTS_FLAG_PAUSED;
             }
             break;
@@ -440 +395 @@
         case PDMAUDIOSTREAMCMD_RESUME:
         {
-            if (pGstStream->fStatus & PDMAUDIOSTREAMSTS_FLAG_PAUSED)
+            if (pStream->fStatus & PDMAUDIOSTREAMSTS_FLAG_PAUSED)
             {
-                if (pHstStream)
-                    rc = drvAudioStreamControlInternalBackend(pThis, pHstStream, PDMAUDIOSTREAMCMD_RESUME);
-
+                rc = drvAudioStreamControlInternalBackend(pThis, pStream, PDMAUDIOSTREAMCMD_RESUME);
                 if (RT_SUCCESS(rc))
-                    pGstStream->fStatus &= ~PDMAUDIOSTREAMSTS_FLAG_PAUSED;
+                    pStream->fStatus &= ~PDMAUDIOSTREAMSTS_FLAG_PAUSED;
             }
             break;
@@ -477 +430 @@
     AssertPtrReturn(pStream, VERR_INVALID_POINTER);
 
-    PPDMAUDIOSTREAM pHstStream = drvAudioGetHostStream(pStream);
-    if (!pHstStream) /* Stream does not have a host backend? Bail out. */
-        return VERR_NOT_FOUND;
-
 #ifdef LOG_ENABLED
-    char *pszHstSts = dbgAudioStreamStatusToStr(pHstStream->fStatus);
-    LogFlowFunc(("[%s] enmStreamCmd=%s, fStatus=%s\n", pHstStream->szName, DrvAudioHlpStreamCmdToStr(enmStreamCmd), pszHstSts));
-    RTStrFree(pszHstSts);
+    char *pszStreamSts = dbgAudioStreamStatusToStr(pStream->fStatus);
+    LogFlowFunc(("[%s] enmStreamCmd=%s, fStatus=%s\n", pStream->szName, DrvAudioHlpStreamCmdToStr(enmStreamCmd), pszStreamSts));
+    RTStrFree(pszStreamSts);
 #endif /* LOG_ENABLED */
 
-    LogRel2(("Audio: %s stream '%s'\n", DrvAudioHlpStreamCmdToStr(enmStreamCmd), pHstStream->szName));
-
-    AssertPtr(pThis->pHostDrvAudio);
+    if (!pThis->pHostDrvAudio) /* If not lower driver is configured, bail out. */
+        return VINF_SUCCESS;
+
+    LogRel2(("Audio: %s stream '%s'\n", DrvAudioHlpStreamCmdToStr(enmStreamCmd), pStream->szName));
 
     int rc = VINF_SUCCESS;
@@ -497 +447 @@
         case PDMAUDIOSTREAMCMD_ENABLE:
         {
-            if (!(pHstStream->fStatus & PDMAUDIOSTREAMSTS_FLAG_ENABLED))
+            if (!(pStream->fStatus & PDMAUDIOSTREAMSTS_FLAG_ENABLED))
+                rc = pThis->pHostDrvAudio->pfnStreamControl(pThis->pHostDrvAudio, pStream->pvBackend, PDMAUDIOSTREAMCMD_ENABLE);
+            break;
+        }
+
+        case PDMAUDIOSTREAMCMD_DISABLE:
+        {
+            if (pStream->fStatus & PDMAUDIOSTREAMSTS_FLAG_ENABLED)
             {
-                rc = pThis->pHostDrvAudio->pfnStreamControl(pThis->pHostDrvAudio, pHstStream->pvBackend,
-                                                            PDMAUDIOSTREAMCMD_ENABLE);
+                rc = pThis->pHostDrvAudio->pfnStreamControl(pThis->pHostDrvAudio, pStream->pvBackend, PDMAUDIOSTREAMCMD_DISABLE);
                 if (RT_SUCCESS(rc))
-                {
-                    pHstStream->fStatus |= PDMAUDIOSTREAMSTS_FLAG_ENABLED;
-                }
+                    AudioMixBufReset(&pStream->Host.MixBuf);
             }
             break;
         }
 
-        case PDMAUDIOSTREAMCMD_DISABLE:
-        {
-            if (pHstStream->fStatus & PDMAUDIOSTREAMSTS_FLAG_ENABLED)
-            {
-                rc = pThis->pHostDrvAudio->pfnStreamControl(pThis->pHostDrvAudio, pHstStream->pvBackend,
-                                                            PDMAUDIOSTREAMCMD_DISABLE);
-                if (RT_SUCCESS(rc))
-                {
-                    pHstStream->fStatus = PDMAUDIOSTREAMSTS_FLAG_INITIALIZED; /* Reset to initialized state. */
-                    AudioMixBufReset(&pHstStream->MixBuf);
-                }
-            }
+        case PDMAUDIOSTREAMCMD_PAUSE:
+        {
+            /* Only pause if the stream is enabled. */
+            if (!(pStream->fStatus & PDMAUDIOSTREAMSTS_FLAG_ENABLED))
+                break;
+
+            if (!(pStream->fStatus & PDMAUDIOSTREAMSTS_FLAG_PAUSED))
+                rc = pThis->pHostDrvAudio->pfnStreamControl(pThis->pHostDrvAudio, pStream->pvBackend, PDMAUDIOSTREAMCMD_PAUSE);
             break;
         }
 
-        case PDMAUDIOSTREAMCMD_PAUSE:
-        {
-            /* Only pause if the stream is enabled. */
-            if (!(pHstStream->fStatus & PDMAUDIOSTREAMSTS_FLAG_ENABLED))
+        case PDMAUDIOSTREAMCMD_RESUME:
+        {
+            /* Only need to resume if the stream is enabled. */
+            if (!(pStream->fStatus & PDMAUDIOSTREAMSTS_FLAG_ENABLED))
                 break;
 
-            if (!(pHstStream->fStatus & PDMAUDIOSTREAMSTS_FLAG_PAUSED))
-            {
-                rc = pThis->pHostDrvAudio->pfnStreamControl(pThis->pHostDrvAudio, pHstStream->pvBackend,
-                                                            PDMAUDIOSTREAMCMD_PAUSE);
-                if (RT_SUCCESS(rc))
-                {
-                    pHstStream->fStatus |= PDMAUDIOSTREAMSTS_FLAG_PAUSED;
-                }
-            }
+            if (pStream->fStatus & PDMAUDIOSTREAMSTS_FLAG_PAUSED)
+                rc = pThis->pHostDrvAudio->pfnStreamControl(pThis->pHostDrvAudio, pStream->pvBackend, PDMAUDIOSTREAMCMD_RESUME);
             break;
         }
 
-        case PDMAUDIOSTREAMCMD_RESUME:
-        {
-            /* Only need to resume if the stream is enabled. */
-            if (!(pHstStream->fStatus & PDMAUDIOSTREAMSTS_FLAG_ENABLED))
-                break;
-
-            if (pHstStream->fStatus & PDMAUDIOSTREAMSTS_FLAG_PAUSED)
-            {
-                rc = pThis->pHostDrvAudio->pfnStreamControl(pThis->pHostDrvAudio, pHstStream->pvBackend,
-                                                            PDMAUDIOSTREAMCMD_RESUME);
-                if (RT_SUCCESS(rc))
-                {
-                    pHstStream->fStatus &= ~PDMAUDIOSTREAMSTS_FLAG_PAUSED;
-                }
-            }
-            break;
-        }
-
         case PDMAUDIOSTREAMCMD_DRAIN:
         {
-            rc = pThis->pHostDrvAudio->pfnStreamControl(pThis->pHostDrvAudio, pHstStream->pvBackend, PDMAUDIOSTREAMCMD_DRAIN);
+            rc = pThis->pHostDrvAudio->pfnStreamControl(pThis->pHostDrvAudio, pStream->pvBackend, PDMAUDIOSTREAMCMD_DRAIN);
             break;
         }
@@ -578 +503 @@
         if (   rc != VERR_NOT_IMPLEMENTED
             && rc != VERR_NOT_SUPPORTED)
-            LogRel(("Audio: %s stream '%s' failed with %Rrc\n", DrvAudioHlpStreamCmdToStr(enmStreamCmd), pHstStream->szName, rc));
+            LogRel(("Audio: %s stream '%s' failed with %Rrc\n", DrvAudioHlpStreamCmdToStr(enmStreamCmd), pStream->szName, rc));
 
         LogFunc(("[%s] %s failed with %Rrc\n", pStream->szName, DrvAudioHlpStreamCmdToStr(enmStreamCmd), rc));
@@ -603 +528 @@
     AssertPtrReturn(pCfgGuest, VERR_INVALID_POINTER);
 
-    PPDMAUDIOSTREAM pHstStream = drvAudioGetHostStream(pStream);
-    PPDMAUDIOSTREAM pGstStream = pHstStream ? pHstStream->pPair : pStream;
-    AssertPtr(pGstStream);
-
-/*    pCfgHost->Backend.cfPreBuf = DrvAudioHlpMsToFrames(&pCfgHost->Props,
-                                                       pCfgGuest->enmDir == PDMAUDIODIR_IN
-                                                       ? pThis->In.msLatencyHost : pThis->Out.msLatencyHost);*/
-    /* Latency can be 0 if not configured. */
-
     /*
      * Init host stream.
@@ -620 +536 @@
 
 #ifdef DEBUG
-    LogFunc(("[%s] Requested host format:\n", pHstStream->szName));
+    LogFunc(("[%s] Requested host format:\n", pStream->szName));
     DrvAudioHlpStreamCfgPrint(pCfgHost);
 #endif
 
-    LogRel2(("Audio: Creating stream '%s'\n", pHstStream->szName));
+    LogRel2(("Audio: Creating stream '%s'\n", pStream->szName));
     LogRel2(("Audio: Guest %s format for '%s': %RU32Hz, %RU8%s, %RU8 %s\n",
-             pCfgGuest->enmDir == PDMAUDIODIR_IN ? "recording" : "playback", pGstStream->szName,
+             pCfgGuest->enmDir == PDMAUDIODIR_IN ? "recording" : "playback", pStream->szName,
              pCfgGuest->Props.uHz, pCfgGuest->Props.cBits, pCfgGuest->Props.fSigned ? "S" : "U",
              pCfgGuest->Props.cChannels, pCfgGuest->Props.cChannels == 1 ? "Channel" : "Channels"));
     LogRel2(("Audio: Requested host %s format for '%s': %RU32Hz, %RU8%s, %RU8 %s\n",
-             pCfgHost->enmDir == PDMAUDIODIR_IN ? "recording" : "playback", pHstStream->szName,
+             pCfgHost->enmDir == PDMAUDIODIR_IN ? "recording" : "playback", pStream->szName,
              pCfgHost->Props.uHz, pCfgHost->Props.cBits, pCfgHost->Props.fSigned ? "S" : "U",
              pCfgHost->Props.cChannels, pCfgHost->Props.cChannels == 1 ? "Channel" : "Channels"));
 
     PDMAUDIOSTREAMCFG CfgHostAcq;
-    int rc = drvAudioStreamCreateInternalBackend(pThis, pHstStream, pCfgHost, &CfgHostAcq);
+    int rc = drvAudioStreamCreateInternalBackend(pThis, pStream, pCfgHost, &CfgHostAcq);
     if (RT_FAILURE(rc))
         return rc;
 
 #ifdef DEBUG
-    LogFunc(("[%s] Acquired host format:\n",  pHstStream->szName));
+    LogFunc(("[%s] Acquired host format:\n",  pStream->szName));
     DrvAudioHlpStreamCfgPrint(&CfgHostAcq);
 #endif
@@ -672 +588 @@
         LogRel2(("Audio: Warning: Pre-buffering size (%RU32 frames) of stream '%s' does not match buffer size (%RU32 frames), "
                  "setting pre-buffering size to %RU32 frames\n",
-                 CfgHostAcq.Backend.cfPreBuf, pHstStream->szName, CfgHostAcq.Backend.cfBufferSize, CfgHostAcq.Backend.cfBufferSize));
+                 CfgHostAcq.Backend.cfPreBuf, pStream->szName, CfgHostAcq.Backend.cfBufferSize, CfgHostAcq.Backend.cfBufferSize));
         CfgHostAcq.Backend.cfPreBuf = CfgHostAcq.Backend.cfBufferSize;
     }
@@ -679 +595 @@
     {
         LogRel2(("Audio: Warning: Period size (%RU32 frames) of stream '%s' does not match buffer size (%RU32 frames), setting to %RU32 frames\n",
-                 CfgHostAcq.Backend.cfPeriod, pHstStream->szName, CfgHostAcq.Backend.cfBufferSize, CfgHostAcq.Backend.cfBufferSize));
+                 CfgHostAcq.Backend.cfPeriod, pStream->szName, CfgHostAcq.Backend.cfBufferSize, CfgHostAcq.Backend.cfBufferSize));
         CfgHostAcq.Backend.cfPeriod = CfgHostAcq.Backend.cfBufferSize;
     }
@@ -686 +602 @@
 
     LogRel2(("Audio: Buffer size of stream '%s' is %RU32ms (%RU32 frames)\n",
-             pHstStream->szName, msBufferSize, CfgHostAcq.Backend.cfBufferSize));
+             pStream->szName, msBufferSize, CfgHostAcq.Backend.cfBufferSize));
 
     /* If no own pre-buffer is set, let the backend choose. */
     uint32_t msPreBuf = DrvAudioHlpFramesToMilli(CfgHostAcq.Backend.cfPreBuf, &pCfgHost->Props);
     LogRel2(("Audio: Pre-buffering size of stream '%s' is %RU32ms (%RU32 frames)\n",
-             pHstStream->szName, msPreBuf, CfgHostAcq.Backend.cfPreBuf));
+             pStream->szName, msPreBuf, CfgHostAcq.Backend.cfPreBuf));
 
     /* Make sure the configured buffer size by the backend at least can hold the configured latency. */
@@ -697 +613 @@
 
     LogRel2(("Audio: Period size of stream '%s' is %RU32ms (%RU32 frames)\n",
-             pHstStream->szName, msPeriod, CfgHostAcq.Backend.cfPeriod));
+             pStream->szName, msPeriod, CfgHostAcq.Backend.cfPeriod));
 
     /* Set set host buffer size multiplicator. */
@@ -703 +619 @@
 
     /* Destroy any former mixing buffer. */
-    AudioMixBufDestroy(&pHstStream->MixBuf);
+    AudioMixBufDestroy(&pStream->Host.MixBuf);
 
     /* Make sure to (re-)set the host buffer's shift size. */
     CfgHostAcq.Props.cShift = PDMAUDIOPCMPROPS_MAKE_SHIFT_PARMS(CfgHostAcq.Props.cBits, CfgHostAcq.Props.cChannels);
 
-    int rc2 = AudioMixBufInit(&pHstStream->MixBuf, pHstStream->szName, &CfgHostAcq.Props,
-                              CfgHostAcq.Backend.cfBufferSize * cHstBufferFactor);
-    AssertRC(rc2);
+    rc = AudioMixBufInit(&pStream->Host.MixBuf, pStream->szName, &CfgHostAcq.Props,
+                        CfgHostAcq.Backend.cfBufferSize * cHstBufferFactor);
+    AssertRC(rc);
 
     /* Make a copy of the acquired host stream configuration. */
-    rc2 = DrvAudioHlpStreamCfgCopy(&pHstStream->Cfg, &CfgHostAcq);
-    AssertRC(rc2);
+    rc = DrvAudioHlpStreamCfgCopy(&pStream->Host.Cfg, &CfgHostAcq);
+    AssertRC(rc);
 
     /*
@@ -721 +637 @@
 
     if (pCfgGuest->Device.uSchedulingHintMs)
-        LogRel2(("Audio: Stream '%s' got a scheduling hint of %RU32ms\n", pGstStream->szName, pCfgGuest->Device.uSchedulingHintMs));
+        LogRel2(("Audio: Stream '%s' got a scheduling hint of %RU32ms\n", pStream->szName, pCfgGuest->Device.uSchedulingHintMs));
 
     /* Destroy any former mixing buffer. */
-    AudioMixBufDestroy(&pGstStream->MixBuf);
+    AudioMixBufDestroy(&pStream->Guest.MixBuf);
 
     /* Set the guests's default audio data layout. */
@@ -735 +651 @@
     const unsigned cGstBufferFactor = 4; /** @todo Make this configurable. */
 
-    rc2 = AudioMixBufInit(&pGstStream->MixBuf, pGstStream->szName, &pCfgGuest->Props,
-                          CfgHostAcq.Backend.cfBufferSize * cGstBufferFactor);
-    AssertRC(rc2);
-
-    if (pCfgGuest->enmDir == PDMAUDIODIR_IN)
-    {
-        /* Host (Parent) -> Guest (Child). */
-        rc2 = AudioMixBufLinkTo(&pHstStream->MixBuf, &pGstStream->MixBuf);
-        AssertRC(rc2);
-    }
-    else
-    {
-        /* Guest (Parent) -> Host (Child). */
-        rc2 = AudioMixBufLinkTo(&pGstStream->MixBuf, &pHstStream->MixBuf);
-        AssertRC(rc2);
-    }
+    rc = AudioMixBufInit(&pStream->Guest.MixBuf, pStream->szName, &pCfgGuest->Props,
+                         CfgHostAcq.Backend.cfBufferSize * cGstBufferFactor);
+    AssertRC(rc);
 
     /* Make a copy of the guest stream configuration. */
-    rc2 = DrvAudioHlpStreamCfgCopy(&pGstStream->Cfg, pCfgGuest);
-    AssertRC(rc2);
+    rc = DrvAudioHlpStreamCfgCopy(&pStream->Guest.Cfg, pCfgGuest);
+    AssertRC(rc);
 
     if (RT_FAILURE(rc))
         LogRel(("Audio: Creating stream '%s' failed with %Rrc\n", pStream->szName, rc));
+
+    if (pCfgGuest->enmDir == PDMAUDIODIR_IN)
+    {
+        /* Host (Parent) -> Guest (Child). */
+        rc = AudioMixBufLinkTo(&pStream->Host.MixBuf, &pStream->Guest.MixBuf);
+        AssertRC(rc);
+    }
+    else
+    {
+        /* Guest (Parent) -> Host (Child). */
+        rc = AudioMixBufLinkTo(&pStream->Guest.MixBuf, &pStream->Host.MixBuf);
+        AssertRC(rc);
+    }
+
+#ifdef VBOX_WITH_STATISTICS
+    char szStatName[255];
+
+    if (pCfgGuest->enmDir == PDMAUDIODIR_IN)
+    {
+        RTStrPrintf(szStatName, sizeof(szStatName), "Guest/%s/BytesElapsed", pStream->szName);
+        PDMDrvHlpSTAMRegCounterEx(pThis->pDrvIns, &pStream->In.Stats.BytesElapsed,
+                                  szStatName, STAMUNIT_BYTES, "Elapsed bytes read.");
+
+        RTStrPrintf(szStatName, sizeof(szStatName), "Guest/%s/BytesRead", pStream->szName);
+        PDMDrvHlpSTAMRegCounterEx(pThis->pDrvIns, &pStream->In.Stats.BytesTotalRead,
+                                  szStatName, STAMUNIT_BYTES, "Total bytes read.");
+
+        RTStrPrintf(szStatName, sizeof(szStatName), "Host/%s/FramesCaptured", pStream->szName);
+        PDMDrvHlpSTAMRegCounterEx(pThis->pDrvIns, &pStream->In.Stats.FramesCaptured,
+                                  szStatName, STAMUNIT_COUNT, "Total frames captured.");
+    }
+    else if (pCfgGuest->enmDir == PDMAUDIODIR_OUT)
+    {
+        RTStrPrintf(szStatName, sizeof(szStatName), "Guest/%s/BytesElapsed", pStream->szName);
+        PDMDrvHlpSTAMRegCounterEx(pThis->pDrvIns, &pStream->Out.Stats.BytesElapsed,
+                                  szStatName, STAMUNIT_BYTES, "Elapsed bytes written.");
+
+        RTStrPrintf(szStatName, sizeof(szStatName), "Guest/%s/BytesWritten", pStream->szName);
+        PDMDrvHlpSTAMRegCounterEx(pThis->pDrvIns, &pStream->Out.Stats.BytesTotalWritten,
+                                  szStatName, STAMUNIT_BYTES, "Total bytes written.");
+
+        RTStrPrintf(szStatName, sizeof(szStatName), "Host/%s/FramesPlayed", pStream->szName);
+        PDMDrvHlpSTAMRegCounterEx(pThis->pDrvIns, &pStream->Out.Stats.FramesPlayed,
+                                  szStatName, STAMUNIT_COUNT, "Total frames played.");
+    }
+    else
+        AssertFailed();
+#endif
 
     LogFlowFunc(("[%s] Returning %Rrc\n", pStream->szName, rc));
@@ -800 +751 @@
 
     /* Mark all host streams to re-initialize. */
-    PPDMAUDIOSTREAM pHstStream;
-    RTListForEach(&pThis->lstHstStreams, pHstStream, PDMAUDIOSTREAM, Node)
-        pHstStream->fStatus |= PDMAUDIOSTREAMSTS_FLAG_PENDING_REINIT;
+    PPDMAUDIOSTREAM pStream;
+    RTListForEach(&pThis->lstStreams, pStream, PDMAUDIOSTREAM, Node)
+        pStream->fStatus |= PDMAUDIOSTREAMSTS_FLAG_PENDING_REINIT;
 
 # ifdef VBOX_WITH_AUDIO_ENUM
@@ -829 +780 @@
     LogFlowFunc(("[%s]\n", pStream->szName));
 
-    PPDMAUDIOSTREAM pHstStream = drvAudioGetHostStream(pStream);
-    AssertPtr(pHstStream);
-
     /*
      * Gather current stream status.
      */
-    bool fIsEnabled = RT_BOOL(pHstStream->fStatus & PDMAUDIOSTREAMSTS_FLAG_ENABLED); /* Stream is enabled? */
+    bool fIsEnabled = RT_BOOL(pStream->fStatus & PDMAUDIOSTREAMSTS_FLAG_ENABLED); /* Stream is enabled? */
 
     /*
      * Destroy and re-create stream on backend side.
      */
-    int rc = drvAudioStreamControlInternalBackend(pThis, pHstStream, PDMAUDIOSTREAMCMD_DISABLE);
+    int rc = drvAudioStreamControlInternalBackend(pThis, pStream, PDMAUDIOSTREAMCMD_DISABLE);
     if (RT_SUCCESS(rc))
     {
-        rc = drvAudioStreamDestroyInternalBackend(pThis, pHstStream);
+        rc = drvAudioStreamDestroyInternalBackend(pThis, pStream);
         if (RT_SUCCESS(rc))
         {
-            rc = drvAudioStreamCreateInternalBackend(pThis, pHstStream, &pHstStream->Cfg, NULL /* pCfgAcq */);
-            /** @todo Validate (re-)acquired configuration with pHstStream->Cfg? */
-        }
-    }
+            rc = drvAudioStreamCreateInternalBackend(pThis, pStream, &pStream->Host.Cfg, NULL /* pCfgAcq */);
+            /** @todo Validate (re-)acquired configuration with pStream->Host.Cfg? */
+        }
+    }
+
+    /* Do the internal reset. */
+    drvAudioStreamResetInternal(pThis, pStream);
 
     /*
      * Restore previous stream state.
      */
-    if (RT_SUCCESS(rc))
-    {
-        PPDMAUDIOSTREAM pGstStream = pHstStream->pPair;
-
-        if (fIsEnabled)
-        {
-            rc = drvAudioStreamControlInternalBackend(pThis, pHstStream, PDMAUDIOSTREAMCMD_ENABLE);
-            if (RT_SUCCESS(rc))
-            {
-                if (pGstStream)
-                {
-                    /* Also reset the guest stream mixing buffer. */
-                    AudioMixBufReset(&pGstStream->MixBuf);
-                }
-            }
-        }
-
-#ifdef VBOX_WITH_STATISTICS
-        /*
-         * Reset statistics.
-         */
-        if (RT_SUCCESS(rc))
-        {
-            if (pHstStream->enmDir == PDMAUDIODIR_IN)
-            {
-                STAM_COUNTER_RESET(&pHstStream->In.Stats.BytesElapsed);
-                STAM_COUNTER_RESET(&pHstStream->In.Stats.BytesTotalRead);
-                STAM_COUNTER_RESET(&pHstStream->In.Stats.FramesCaptured);
-
-                if (pGstStream)
-                {
-                    Assert(pGstStream->enmDir == pHstStream->enmDir);
-
-                    STAM_COUNTER_RESET(&pGstStream->In.Stats.BytesElapsed);
-                    STAM_COUNTER_RESET(&pGstStream->In.Stats.BytesTotalRead);
-                    STAM_COUNTER_RESET(&pGstStream->In.Stats.FramesCaptured);
-                }
-            }
-            else if (pHstStream->enmDir == PDMAUDIODIR_OUT)
-            {
-                STAM_COUNTER_RESET(&pHstStream->Out.Stats.BytesElapsed);
-                STAM_COUNTER_RESET(&pHstStream->Out.Stats.BytesTotalWritten);
-                STAM_COUNTER_RESET(&pHstStream->Out.Stats.FramesPlayed);
-
-                if (pGstStream)
-                {
-                    Assert(pGstStream->enmDir == pHstStream->enmDir);
-
-                    STAM_COUNTER_RESET(&pGstStream->Out.Stats.BytesElapsed);
-                    STAM_COUNTER_RESET(&pGstStream->Out.Stats.BytesTotalWritten);
-                    STAM_COUNTER_RESET(&pGstStream->Out.Stats.FramesPlayed);
-                }
-            }
-            else
-                AssertFailed();
-        }
-#endif
-    }
+    if (fIsEnabled)
+        rc = drvAudioStreamControlInternalBackend(pThis, pStream, PDMAUDIOSTREAMCMD_ENABLE);
 
     if (RT_FAILURE(rc))
@@ -918 +813 @@
     LogFunc(("[%s] Returning %Rrc\n", pStream->szName, rc));
     return rc;
+}
+
+static void drvAudioStreamResetInternal(PDRVAUDIO pThis, PPDMAUDIOSTREAM pStream)
+{
+    RT_NOREF(pThis);
+
+    AudioMixBufReset(&pStream->Guest.MixBuf);
+    AudioMixBufReset(&pStream->Host.MixBuf);
+
+#ifdef VBOX_WITH_STATISTICS
+    /*
+     * Reset statistics.
+     */
+    if (pStream->enmDir == PDMAUDIODIR_IN)
+    {
+        STAM_COUNTER_RESET(&pStream->In.Stats.BytesElapsed);
+        STAM_COUNTER_RESET(&pStream->In.Stats.BytesTotalRead);
+        STAM_COUNTER_RESET(&pStream->In.Stats.FramesCaptured);
+    }
+    else if (pStream->enmDir == PDMAUDIODIR_OUT)
+    {
+        STAM_COUNTER_RESET(&pStream->Out.Stats.BytesElapsed);
+        STAM_COUNTER_RESET(&pStream->Out.Stats.BytesTotalWritten);
+        STAM_COUNTER_RESET(&pStream->Out.Stats.FramesPlayed);
+    }
+    else
+        AssertFailed();
+#endif
 }
 
@@ -949 +872 @@
 
 #ifdef LOG_ENABLED
-    char *pszGstSts = NULL;
-    char *pszHstSts = NULL;
+    char *pszStreamSts = NULL;
 #endif
 
@@ -969 +891 @@
         }
 
-        PPDMAUDIOSTREAM pHstStream = drvAudioGetHostStream(pStream);
-        if (!pHstStream)
-        {
-            rc = VERR_NOT_AVAILABLE;
-            break;
-        }
+        AssertMsg(DrvAudioHlpBytesIsAligned(cbBuf, &pStream->Guest.Cfg.Props),
+                  ("Writing audio data (%RU32 bytes) to stream '%s' is not properly aligned\n", cbBuf, pStream->szName));
 
 #ifdef LOG_ENABLED
-        pszHstSts = dbgAudioStreamStatusToStr(pHstStream->fStatus);
-        AssertPtr(pszHstSts);
+        pszStreamSts = dbgAudioStreamStatusToStr(pStream->fStatus);
+        AssertPtr(pszStreamSts);
 #endif
-        PPDMAUDIOSTREAM pGstStream = pHstStream->pPair;
-        AssertPtr(pGstStream);
-
-        AssertMsg(DrvAudioHlpBytesIsAligned(cbBuf, &pGstStream->Cfg.Props),
-                  ("Writing audio data (%RU32 bytes) to stream '%s' is not properly aligned\n", cbBuf, pGstStream->szName));
-
-#ifdef LOG_ENABLED
-        pszGstSts = dbgAudioStreamStatusToStr(pGstStream->fStatus);
-        AssertPtr(pszGstSts);
-#endif
-
-        if (!(pGstStream->fStatus & PDMAUDIOSTREAMSTS_FLAG_ENABLED))
-        {
-            Log3Func(("[%s] Writing to disabled guest output stream not possible (status is %s, host status %s)\n",
-                      pGstStream->szName, pszGstSts, pszHstSts));
+        if (!(pStream->fStatus & PDMAUDIOSTREAMSTS_FLAG_ENABLED))
+        {
+            Log3Func(("[%s] Writing to disabled guest output stream not possible (status is %s)\n",
+                      pStream->szName, pszStreamSts));
 #ifdef DEBUG_andy
             AssertFailed();
@@ -1002 +909 @@
         }
 
-        const uint32_t cbFree = AudioMixBufFreeBytes(&pHstStream->MixBuf);
+        const uint32_t cbFree = AudioMixBufFreeBytes(&pStream->Host.MixBuf);
         if (cbFree < cbBuf)
             LogRel2(("Audio: Lost audio output (%RU64ms, %RU32 free but needs %RU32) due to full host stream buffer '%s'\n",
-                     DrvAudioHlpBytesToMilli(cbBuf - cbFree, &pHstStream->Cfg.Props), cbFree, cbBuf, pHstStream->szName));
+                     DrvAudioHlpBytesToMilli(cbBuf - cbFree, &pStream->Host.Cfg.Props), cbFree, cbBuf, pStream->szName));
 
         uint32_t cbToWrite = RT_MIN(cbBuf, cbFree);
@@ -1017 +924 @@
          * (first) processing (if needed), so always write the incoming data at offset 0. */
         uint32_t cfGstWritten = 0;
-        rc = AudioMixBufWriteAt(&pGstStream->MixBuf, 0 /* offFrames */, pvBuf, cbToWrite, &cfGstWritten);
+        rc = AudioMixBufWriteAt(&pStream->Guest.MixBuf, 0 /* offFrames */, pvBuf, cbToWrite, &cfGstWritten);
         if (   RT_FAILURE(rc)
             || !cfGstWritten)
         {
             AssertMsgFailed(("[%s] Write failed: cbToWrite=%RU32, cfWritten=%RU32, rc=%Rrc\n",
-                             pGstStream->szName, cbToWrite, cfGstWritten, rc));
+                             pStream->szName, cbToWrite, cfGstWritten, rc));
             break;
         }
 
         if (pThis->Out.Cfg.Dbg.fEnabled)
-            DrvAudioHlpFileWrite(pHstStream->Out.Dbg.pFileStreamWrite, pvBuf, cbToWrite, 0 /* fFlags */);
+            DrvAudioHlpFileWrite(pStream->Out.Dbg.pFileStreamWrite, pvBuf, cbToWrite, 0 /* fFlags */);
 
 #ifdef VBOX_WITH_STATISTICS
@@ -1035 +942 @@
         if (cfGstWritten)
         {
-            int rc2 = AudioMixBufMixToParentEx(&pGstStream->MixBuf, 0 /* cSrcOffset */, cfGstWritten /* cSrcFrames */,
+            int rc2 = AudioMixBufMixToParentEx(&pStream->Guest.MixBuf, 0 /* cSrcOffset */, cfGstWritten /* cSrcFrames */,
                                                &cfGstMixed /* pcSrcMixed */);
             if (RT_FAILURE(rc2))
             {
                 AssertMsgFailed(("[%s] Mixing failed: cbToWrite=%RU32, cfWritten=%RU32, cfMixed=%RU32, rc=%Rrc\n",
-                                 pGstStream->szName, cbToWrite, cfGstWritten, cfGstMixed, rc2));
+                                 pStream->szName, cbToWrite, cfGstWritten, cfGstMixed, rc2));
             }
             else
             {
                 Log3Func(("[%s] Buffer: Writing %RU32 frames (%RU64ms), now filled with %RU64ms -- %RU8%%\n",
-                          pHstStream->szName, cfGstWritten, DrvAudioHlpFramesToMilli(cfGstWritten, &pHstStream->Cfg.Props),
-                          DrvAudioHlpFramesToMilli(AudioMixBufUsed(&pHstStream->MixBuf), &pHstStream->Cfg.Props),
-                          AudioMixBufUsed(&pHstStream->MixBuf) * 100 / AudioMixBufSize(&pHstStream->MixBuf)));
-
-                pHstStream->tsLastReadWrittenNs = RTTimeNanoTS();
+                          pStream->szName, cfGstWritten, DrvAudioHlpFramesToMilli(cfGstWritten, &pStream->Guest.Cfg.Props),
+                          DrvAudioHlpFramesToMilli(AudioMixBufUsed(&pStream->Host.MixBuf), &pStream->Host.Cfg.Props),
+                          AudioMixBufUsed(&pStream->Host.MixBuf) * 100 / AudioMixBufSize(&pStream->Host.MixBuf)));
+
+                pStream->tsLastReadWrittenNs = RTTimeNanoTS();
 
                 /* Keep going. */
@@ -1057 +964 @@
                 rc = rc2;
 
-            cbWrittenTotal = AUDIOMIXBUF_F2B(&pGstStream->MixBuf, cfGstWritten);
+            cbWrittenTotal = AUDIOMIXBUF_F2B(&pStream->Guest.MixBuf, cfGstWritten);
 #ifdef DEBUG
-            if (pHstStream->fThresholdReached)
-                pHstStream->Out.Dbg.cbJitterWrittenPlayed += cbWrittenTotal;
+            if (pStream->fThresholdReached)
+                pStream->Out.Dbg.cbJitterWrittenPlayed += cbWrittenTotal;
 #endif
 
 #ifdef VBOX_WITH_STATISTICS
-            STAM_COUNTER_ADD(&pThis->Stats.TotalFramesMixedOut,      cfGstMixed);
+            STAM_COUNTER_ADD(&pThis->Stats.TotalFramesMixedOut,     cfGstMixed);
             Assert(cfGstWritten >= cfGstMixed);
-            STAM_COUNTER_ADD(&pThis->Stats.TotalFramesLostOut,       cfGstWritten - cfGstMixed);
-            STAM_COUNTER_ADD(&pThis->Stats.TotalBytesWritten,        cbWrittenTotal);
-            STAM_COUNTER_ADD(&pGstStream->Out.Stats.BytesTotalWritten, cbWrittenTotal);
+            STAM_COUNTER_ADD(&pThis->Stats.TotalFramesLostOut,      cfGstWritten - cfGstMixed);
+            STAM_COUNTER_ADD(&pThis->Stats.TotalBytesWritten,       cbWrittenTotal);
+            STAM_COUNTER_ADD(&pStream->Out.Stats.BytesTotalWritten, cbWrittenTotal);
 #endif
         }
 
-        Log3Func(("[%s] cbToWrite=%RU32, cfUsed=%RU32, cfLive=%RU32, cfWritten=%RU32, cfMixed=%RU32, rc=%Rrc\n",
-                  pGstStream->szName, cbToWrite, AudioMixBufUsed(&pGstStream->MixBuf),
-                  AudioMixBufLive(&pGstStream->MixBuf), cfGstWritten, cfGstMixed, rc));
+        Log3Func(("[%s] cbToWrite=%RU32, cfHstUsed=%RU32, cfHstfLive=%RU32, cfGstWritten=%RU32, cfGstMixed=%RU32, rc=%Rrc\n",
+                  pStream->szName, cbToWrite, AudioMixBufUsed(&pStream->Host.MixBuf),
+                  AudioMixBufLive(&pStream->Host.MixBuf), cfGstWritten, cfGstMixed, rc));
 
     } while (0);
 
-    Log3Func(("[%s] fEnabled=%RTbool, cbWrittenTotal=%RU32, rc=%Rrc\n", pStream->szName, pThis->Out.fEnabled, cbWrittenTotal, rc));
+    Log3Func(("[%s] fEnabled=%RTbool, cbWrittenTotal=%RU32, rc=%Rrc\n",
+              pStream->szName, pThis->Out.fEnabled, cbWrittenTotal, rc));
 
 #ifdef LOG_ENABLED
-    RTStrFree(pszHstSts);
-    RTStrFree(pszGstSts);
+    RTStrFree(pszStreamSts);
 #endif
 
@@ -1172 +1079 @@
         return VINF_SUCCESS;
 
-    PPDMAUDIOSTREAM pHstStream = drvAudioGetHostStream(pStream);
-    AssertPtr(pHstStream);
-    PPDMAUDIOSTREAM pGstStream = pHstStream ? pHstStream->pPair : NULL;
-    AssertPtr(pGstStream);
-
     int rc;
 
     /* Is the stream scheduled for re-initialization? Do so now. */
-    if (pHstStream->fStatus & PDMAUDIOSTREAMSTS_FLAG_PENDING_REINIT)
+    if (pStream->fStatus & PDMAUDIOSTREAMSTS_FLAG_PENDING_REINIT)
     {
 #ifdef VBOX_WITH_AUDIO_ENUM
@@ -1194 +1096 @@
         /* Remove the pending re-init flag in any case, regardless whether the actual re-initialization succeeded
          * or not. If it failed, the backend needs to notify us again to try again at some later point in time. */
-        pHstStream->fStatus &= ~PDMAUDIOSTREAMSTS_FLAG_PENDING_REINIT;
+        pStream->fStatus &= ~PDMAUDIOSTREAMSTS_FLAG_PENDING_REINIT;
 
         rc = drvAudioStreamReInitInternal(pThis, pStream);
@@ -1202 +1104 @@
 
 #ifdef LOG_ENABLED
-    char *pszHstSts = dbgAudioStreamStatusToStr(pHstStream->fStatus);
-    Log3Func(("[%s] fStatus=%s\n", pHstStream->szName, pszHstSts));
-    RTStrFree(pszHstSts);
+    char *pszStreamSts = dbgAudioStreamStatusToStr(pStream->fStatus);
+    Log3Func(("[%s] fStatus=%s\n", pStream->szName, pszStreamSts));
+    RTStrFree(pszStreamSts);
 #endif /* LOG_ENABLED */
 
     /* Not enabled or paused? Skip iteration. */
-    if (   !(pHstStream->fStatus & PDMAUDIOSTREAMSTS_FLAG_ENABLED)
-        ||  (pHstStream->fStatus & PDMAUDIOSTREAMSTS_FLAG_PAUSED))
+    if (   !(pStream->fStatus & PDMAUDIOSTREAMSTS_FLAG_ENABLED)
+        ||  (pStream->fStatus & PDMAUDIOSTREAMSTS_FLAG_PAUSED))
     {
         return VINF_SUCCESS;
@@ -1221 +1123 @@
         uint32_t cfMixed = 0;
 
-        rc = pThis->pHostDrvAudio->pfnStreamIterate(pThis->pHostDrvAudio, pHstStream->pvBackend);
+        rc = pThis->pHostDrvAudio->pfnStreamIterate(pThis->pHostDrvAudio, pStream->pvBackend);
         if (RT_FAILURE(rc))
             break;
 
-        if (pHstStream->enmDir == PDMAUDIODIR_IN)
+        if (pStream->enmDir == PDMAUDIODIR_IN)
         {
             /* Has the host captured any frames which were not mixed to the guest side yet? */
-            uint32_t cfCaptured = AudioMixBufUsed(&pHstStream->MixBuf);
+            uint32_t cfCaptured = AudioMixBufUsed(&pStream->Host.MixBuf);
             if (cfCaptured)
             {
                 /* When capturing frames, the guest is the parent while the host is the child.
                  * So try mixing not yet mixed host-side frames to the guest-side buffer. */
-                rc = AudioMixBufMixToParent(&pHstStream->MixBuf, cfCaptured, &cfMixed);
+                rc = AudioMixBufMixToParent(&pStream->Host.MixBuf, cfCaptured, &cfMixed);
                 if (RT_FAILURE(rc))
                 {
                     if (rc == VERR_BUFFER_OVERFLOW)
-                        LogRel2(("Audio: Guest input stream '%s' full, expect stuttering audio capture\n", pGstStream->szName));
+                        LogRel2(("Audio: Guest input stream '%s' full\n", pStream->szName));
                     else
-                        LogRel2(("Audio: Mixing to guest input stream '%s' failed: %Rrc\n", pGstStream->szName, rc));
+                        LogRel2(("Audio: Mixing to guest input stream '%s' failed: %Rrc\n", pStream->szName, rc));
 #ifdef DEBUG_andy_disabled
                     AssertFailed();
@@ -1250 +1152 @@
                 STAM_COUNTER_ADD(&pThis->Stats.TotalFramesLostIn,  cfCaptured - cfMixed);
 #endif
-                Log3Func(("[%s] %RU32/%RU32 input frames mixed, rc=%Rrc\n", pHstStream->szName, cfMixed, cfCaptured, rc));
+                Log3Func(("[%s] %RU32/%RU32 input frames mixed, rc=%Rrc\n", pStream->szName, cfMixed, cfCaptured, rc));
             }
             else
@@ -1259 +1161 @@
             }
         }
-        else if (pHstStream->enmDir == PDMAUDIODIR_OUT)
+        else if (pStream->enmDir == PDMAUDIODIR_OUT)
         {
             /* No audio frames to transfer from guest to host (anymore)?
              * Then try closing this stream if marked so in the next block. */
-            const uint32_t cfLive = AudioMixBufLive(&pHstStream->MixBuf);
+            const uint32_t cfLive = AudioMixBufLive(&pStream->Host.MixBuf);
             fTryClosePending = cfLive == 0;
-            Log3Func(("[%s] fTryClosePending=%RTbool, cfLive=%RU32\n", pHstStream->szName, fTryClosePending, cfLive));
+            Log3Func(("[%s] fTryClosePending=%RTbool, cfLive=%RU32\n", pStream->szName, fTryClosePending, cfLive));
         }
         else
@@ -1272 +1174 @@
         /* Has the host stream marked as pending to disable?
          * Try disabling the stream then. */
-        if (   pHstStream->fStatus & PDMAUDIOSTREAMSTS_FLAG_PENDING_DISABLE
+        if (   pStream->fStatus & PDMAUDIOSTREAMSTS_FLAG_PENDING_DISABLE
             && fTryClosePending)
         {
             /* Tell the backend to drain the stream, that is, play the remaining (buffered) data
              * on the backend side. */
-            rc = drvAudioStreamControlInternalBackend(pThis, pHstStream, PDMAUDIOSTREAMCMD_DRAIN);
+            rc = drvAudioStreamControlInternalBackend(pThis, pStream, PDMAUDIOSTREAMCMD_DRAIN);
             if (rc == VERR_NOT_SUPPORTED) /* Not all backends support draining. */
                 rc = VINF_SUCCESS;
@@ -1285 +1187 @@
                 if (pThis->pHostDrvAudio->pfnStreamGetPending) /* Optional to implement. */
                 {
-                    const uint32_t cxPending = pThis->pHostDrvAudio->pfnStreamGetPending(pThis->pHostDrvAudio, pHstStream->pvBackend);
-                    Log3Func(("[%s] cxPending=%RU32\n", pHstStream->szName, cxPending));
+                    const uint32_t cxPending = pThis->pHostDrvAudio->pfnStreamGetPending(pThis->pHostDrvAudio, pStream->pvBackend);
+                    Log3Func(("[%s] cxPending=%RU32\n", pStream->szName, cxPending));
 
                     /* Only try close pending if no audio data is pending on the backend-side anymore. */
@@ -1294 +1196 @@
                 if (fTryClosePending)
                 {
-                    LogFunc(("[%s] Closing pending stream\n", pHstStream->szName));
-                    rc = drvAudioStreamControlInternalBackend(pThis, pHstStream, PDMAUDIOSTREAMCMD_DISABLE);
-                    if (RT_FAILURE(rc))
-                        LogFunc(("[%s] Backend vetoed against closing pending input stream, rc=%Rrc\n", pHstStream->szName, rc));
+                    LogFunc(("[%s] Closing pending stream\n", pStream->szName));
+                    rc = drvAudioStreamControlInternalBackend(pThis, pStream, PDMAUDIOSTREAMCMD_DISABLE);
+                    if (RT_SUCCESS(rc))
+                    {
+                        pStream->fStatus &= ~(PDMAUDIOSTREAMSTS_FLAG_ENABLED | PDMAUDIOSTREAMSTS_FLAG_PENDING_DISABLE);
+                    }
+                    else
+                       LogFunc(("[%s] Backend vetoed against closing pending input stream, rc=%Rrc\n", pStream->szName, rc));
                 }
             }
@@ -1305 +1211 @@
 
     /* Update timestamps. */
-    pGstStream->tsLastIteratedNs = RTTimeNanoTS();
+    pStream->tsLastIteratedNs = RTTimeNanoTS();
 
     if (RT_FAILURE(rc))
-        LogFunc(("[%s] Failed with %Rrc\n",  pHstStream->szName, rc));
+        LogFunc(("[%s] Failed with %Rrc\n",  pStream->szName, rc));
 
     return rc;
-}
-
-/**
- * Links an audio stream to another audio stream (pair).
- *
- * @returns IPRT status code.
- * @param   pStream             Stream to handle linking for.
- * @param   pPair               Stream to link pStream to. Specify NULL to unlink pStream from a former linked stream.
- */
-static int drvAudioStreamLinkToInternal(PPDMAUDIOSTREAM pStream, PPDMAUDIOSTREAM pPair)
-{
-    if (pPair) /* Link. */
-    {
-        pStream->pPair = pPair;
-        pPair->pPair   = pStream;
-
-        LogRel2(("Audio: Linked audio stream '%s' to '%s'\n", pStream->szName, pPair->szName));
-    }
-    else /* Unlink. */
-    {
-        if (pStream->pPair)
-        {
-            LogRel2(("Audio: Unlinked pair '%s' from stream '%s'\n", pStream->pPair->szName, pStream->szName));
-
-            AssertMsg(pStream->pPair->pPair == pStream,
-                      ("Pair '%s' is not linked to '%s' (linked to '%s')\n",
-                       pStream->pPair->szName, pStream->szName, pStream->pPair->pPair ? pStream->pPair->pPair->szName : "<NONE>"));
-
-            pStream->pPair->pPair = NULL; /* Also make sure to unlink the pair from pStream */
-            pStream->pPair = NULL;
-        }
-    }
-
-    return VINF_SUCCESS;
 }
 
@@ -1352 +1224 @@
  * @return  IPRT status code.
  * @param   pThis               Pointer to driver instance.
- * @param   pHstStream          Host stream to play.
+ * @param   pStream             Stream to play.
  * @param   cfToPlay            Number of audio frames to play.
  * @param   pcfPlayed           Returns number of audio frames played. Optional.
  */
 static int drvAudioStreamPlayNonInterleaved(PDRVAUDIO pThis,
-                                            PPDMAUDIOSTREAM pHstStream, uint32_t cfToPlay, uint32_t *pcfPlayed)
-{
-    AssertPtrReturn(pThis,      VERR_INVALID_POINTER);
-    AssertPtrReturn(pHstStream, VERR_INVALID_POINTER);
+                                            PPDMAUDIOSTREAM pStream, uint32_t cfToPlay, uint32_t *pcfPlayed)
+{
+    AssertPtrReturn(pThis,   VERR_INVALID_POINTER);
+    AssertPtrReturn(pStream, VERR_INVALID_POINTER);
     /* pcfPlayed is optional. */
-
-    /* Sanity. */
-    Assert(pHstStream->enmCtx == PDMAUDIOSTREAMCTX_HOST);
-    Assert(pHstStream->enmDir == PDMAUDIODIR_OUT);
-    Assert(pHstStream->Cfg.enmLayout == PDMAUDIOSTREAMLAYOUT_NON_INTERLEAVED);
 
     if (!cfToPlay)
@@ -1375 +1242 @@
     }
 
+    /* Sanity. */
+    Assert(pStream->enmDir == PDMAUDIODIR_OUT);
+    Assert(pStream->Host.Cfg.enmLayout == PDMAUDIOSTREAMLAYOUT_NON_INTERLEAVED);
+
     int rc = VINF_SUCCESS;
 
@@ -1380 +1251 @@
 
     AssertPtr(pThis->pHostDrvAudio->pfnStreamGetWritable);
-    uint32_t cfWritable = AUDIOMIXBUF_B2F(&pHstStream->MixBuf,
-                                          pThis->pHostDrvAudio->pfnStreamGetWritable(pThis->pHostDrvAudio, pHstStream->pvBackend));
-
-    Log3Func(("[%s] cfToPlay=%RU32 (%RU64ms), cfWritable=%RU32 (%RU64ms)\n", pHstStream->szName,
-              cfToPlay, DrvAudioHlpFramesToMilli(cfToPlay, &pHstStream->Cfg.Props),
-              cfWritable, DrvAudioHlpFramesToMilli(cfWritable, &pHstStream->Cfg.Props)));
+    uint32_t cfWritable = AUDIOMIXBUF_B2F(&pStream->Host.MixBuf,
+                                          pThis->pHostDrvAudio->pfnStreamGetWritable(pThis->pHostDrvAudio, pStream->pvBackend));
+
+    Log3Func(("[%s] cfToPlay=%RU32 (%RU64ms), cfWritable=%RU32 (%RU64ms)\n", pStream->szName,
+              cfToPlay, DrvAudioHlpFramesToMilli(cfToPlay, &pStream->Host.Cfg.Props),
+              cfWritable, DrvAudioHlpFramesToMilli(cfWritable, &pStream->Host.Cfg.Props)));
 
     if (cfWritable)
@@ -1402 +1273 @@
             {
                 uint32_t cfRead = 0;
-                rc = AudioMixBufAcquireReadBlock(&pHstStream->MixBuf, auBuf, RT_MIN(cbChunk, AUDIOMIXBUF_F2B(&pHstStream->MixBuf, cfLeft)), &cfRead);
+                rc = AudioMixBufAcquireReadBlock(&pStream->Host.MixBuf,
+                                                 auBuf, RT_MIN(cbChunk, AUDIOMIXBUF_F2B(&pStream->Host.MixBuf, cfLeft)),
+                                                 &cfRead);
                 if (RT_FAILURE(rc))
                     break;
 
-                uint32_t cbRead = AUDIOMIXBUF_F2B(&pHstStream->MixBuf, cfRead);
+                uint32_t cbRead = AUDIOMIXBUF_F2B(&pStream->Host.MixBuf, cfRead);
                 Assert(cbRead <= cbChunk);
 
                 uint32_t cfPlayed = 0;
                 uint32_t cbPlayed = 0;
-                rc = pThis->pHostDrvAudio->pfnStreamPlay(pThis->pHostDrvAudio, pHstStream->pvBackend,
+                rc = pThis->pHostDrvAudio->pfnStreamPlay(pThis->pHostDrvAudio, pStream->pvBackend,
                                                          auBuf, cbRead, &cbPlayed);
                 if (   RT_SUCCESS(rc)
@@ -1417 +1290 @@
                 {
                     if (pThis->Out.Cfg.Dbg.fEnabled)
-                        DrvAudioHlpFileWrite(pHstStream->Out.Dbg.pFilePlayNonInterleaved, auBuf, cbPlayed, 0 /* fFlags */);
+                        DrvAudioHlpFileWrite(pStream->Out.Dbg.pFilePlayNonInterleaved, auBuf, cbPlayed, 0 /* fFlags */);
 
                     if (cbRead != cbPlayed)
                         LogRel2(("Audio: Host stream '%s' played wrong amount (%RU32 bytes read but played %RU32)\n",
-                                 pHstStream->szName, cbRead, cbPlayed));
-
-                    cfPlayed       = AUDIOMIXBUF_B2F(&pHstStream->MixBuf, cbPlayed);
+                                 pStream->szName, cbRead, cbPlayed));
+
+                    cfPlayed       = AUDIOMIXBUF_B2F(&pStream->Host.MixBuf, cbPlayed);
                     cfPlayedTotal += cfPlayed;
 
@@ -1430 +1303 @@
                 }
 
-                AudioMixBufReleaseReadBlock(&pHstStream->MixBuf, cfPlayed);
+                AudioMixBufReleaseReadBlock(&pStream->Host.MixBuf, cfPlayed);
 
                 if (RT_FAILURE(rc))
@@ -1438 +1311 @@
     }
 
-    Log3Func(("[%s] Played %RU32/%RU32 frames, rc=%Rrc\n", pHstStream->szName, cfPlayedTotal, cfToPlay, rc));
+    Log3Func(("[%s] Played %RU32/%RU32 frames, rc=%Rrc\n", pStream->szName, cfPlayedTotal, cfToPlay, rc));
 
     if (RT_SUCCESS(rc))
@@ -1454 +1327 @@
  * @return  IPRT status code.
  * @param   pThis               Pointer to driver instance.
- * @param   pHstStream          Host stream to play.
+ * @param   pStream             Stream to play.
  * @param   cfToPlay            Number of audio frames to play.
  * @param   pcfPlayed           Returns number of audio frames played. Optional.
  */
 static int drvAudioStreamPlayRaw(PDRVAUDIO pThis,
-                                 PPDMAUDIOSTREAM pHstStream, uint32_t cfToPlay, uint32_t *pcfPlayed)
+                                 PPDMAUDIOSTREAM pStream, uint32_t cfToPlay, uint32_t *pcfPlayed)
 {
     AssertPtrReturn(pThis,      VERR_INVALID_POINTER);
-    AssertPtrReturn(pHstStream, VERR_INVALID_POINTER);
+    AssertPtrReturn(pStream, VERR_INVALID_POINTER);
     /* pcfPlayed is optional. */
 
     /* Sanity. */
-    Assert(pHstStream->enmCtx == PDMAUDIOSTREAMCTX_HOST);
-    Assert(pHstStream->enmDir == PDMAUDIODIR_OUT);
-    Assert(pHstStream->Cfg.enmLayout == PDMAUDIOSTREAMLAYOUT_RAW);
+    Assert(pStream->enmDir == PDMAUDIODIR_OUT);
+    Assert(pStream->Host.Cfg.enmLayout == PDMAUDIOSTREAMLAYOUT_RAW);
 
     if (!cfToPlay)
@@ -1482 +1354 @@
 
     AssertPtr(pThis->pHostDrvAudio->pfnStreamGetWritable);
-    uint32_t cfWritable = pThis->pHostDrvAudio->pfnStreamGetWritable(pThis->pHostDrvAudio, pHstStream->pvBackend);
+    uint32_t cfWritable = pThis->pHostDrvAudio->pfnStreamGetWritable(pThis->pHostDrvAudio, pStream->pvBackend);
     if (cfWritable)
     {
@@ -1494 +1366 @@
         {
             uint32_t cfRead = 0;
-            rc = AudioMixBufPeek(&pHstStream->MixBuf, cfLeft, aFrameBuf,
+            rc = AudioMixBufPeek(&pStream->Host.MixBuf, cfLeft, aFrameBuf,
                                  RT_MIN(cfLeft, RT_ELEMENTS(aFrameBuf)), &cfRead);
 
@@ -1506 +1378 @@
                      *       rather on bytes. */
                     Assert(cfRead <= RT_ELEMENTS(aFrameBuf));
-                    rc = pThis->pHostDrvAudio->pfnStreamPlay(pThis->pHostDrvAudio, pHstStream->pvBackend,
+                    rc = pThis->pHostDrvAudio->pfnStreamPlay(pThis->pHostDrvAudio, pStream->pvBackend,
                                                              aFrameBuf, cfRead, &cfPlayed);
                     if (   RT_FAILURE(rc)
@@ -1533 +1405 @@
     }
 
-    Log3Func(("[%s] Played %RU32/%RU32 frames, rc=%Rrc\n", pHstStream->szName, cfPlayedTotal, cfToPlay, rc));
+    Log3Func(("[%s] Played %RU32/%RU32 frames, rc=%Rrc\n", pStream->szName, cfPlayedTotal, cfToPlay, rc));
 
     if (RT_SUCCESS(rc))
@@ -1570 +1442 @@
         return VINF_SUCCESS;
 
-    PPDMAUDIOSTREAM pHstStream = drvAudioGetHostStream(pStream);
-    AssertPtr(pHstStream);
-    PPDMAUDIOSTREAM pGstStream = pHstStream ? pHstStream->pPair : NULL;
-    AssertPtr(pGstStream);
-
-    AssertReleaseMsgReturn(pHstStream != NULL,
-                              ("[%s] Host stream is NULL (cRefs=%RU32, fStatus=%x, enmCtx=%ld)\n",
-                               pStream->szName, pStream->cRefs, pStream->fStatus, pStream->enmCtx),
-                              VERR_NOT_AVAILABLE);
-    AssertReleaseMsgReturn(pGstStream != NULL,
-                            ("[%s] Guest stream is NULL (cRefs=%RU32, fStatus=%x, enmCtx=%ld)\n",
-                               pStream->szName, pStream->cRefs, pStream->fStatus, pStream->enmCtx),
-                               VERR_NOT_AVAILABLE);
-
-    PDMAUDIOSTREAMSTS stsHstStream = pHstStream->fStatus;
+    PDMAUDIOSTREAMSTS stsStream = pStream->fStatus;
 #ifdef LOG_ENABLED
-    char *pszStreamSts = dbgAudioStreamStatusToStr(stsHstStream);
-    Log3Func(("[%s] Buffer: Start stsHstStream=%s\n", pHstStream->szName, pszStreamSts));
+    char *pszStreamSts = dbgAudioStreamStatusToStr(stsStream);
+    Log3Func(("[%s] Buffer: Start fStatus=%s\n", pStream->szName, pszStreamSts));
     RTStrFree(pszStreamSts);
 #endif /* LOG_ENABLED */
@@ -1596 +1454 @@
          * Check if the backend is ready to operate.
          */
-        if (!(stsHstStream & PDMAUDIOSTREAMSTS_FLAG_ENABLED)) /* Stream disabled? Bail out. */
+        if (!(stsStream & PDMAUDIOSTREAMSTS_FLAG_ENABLED)) /* Stream disabled? Bail out. */
             break;
 
-              uint32_t cfLive       = AudioMixBufLive(&pHstStream->MixBuf);
-        const uint8_t  uLivePercent = (100 * cfLive) / AudioMixBufSize(&pHstStream->MixBuf);
-
-        const uint64_t tsDeltaPlayedCapturedNs = RTTimeNanoTS() - pHstStream->tsLastPlayedCapturedNs;
-
-        pHstStream->tsLastPlayedCapturedNs = RTTimeNanoTS();
+              uint32_t cfLive       = AudioMixBufLive(&pStream->Host.MixBuf);
+        const uint8_t  uLivePercent = (100 * cfLive) / AudioMixBufSize(&pStream->Host.MixBuf);
+
+        const uint64_t tsDeltaPlayedCapturedNs = RTTimeNanoTS() - pStream->tsLastPlayedCapturedNs;
+
+        pStream->tsLastPlayedCapturedNs = RTTimeNanoTS();
 
         Log3Func(("[%s] Buffer: Last played %RU64ns (%RU64ms), filled with %RU64ms (%RU8%%) total, "
                   "(cfLive=%RU32, fThresholdReached=%RTbool)\n",
-                  pHstStream->szName, tsDeltaPlayedCapturedNs, tsDeltaPlayedCapturedNs / RT_NS_1MS_64,
-                  DrvAudioHlpFramesToMilli(cfLive, &pHstStream->Cfg.Props),
-                  uLivePercent, cfLive, pHstStream->fThresholdReached));
-
-        bool fDoPlay      = pHstStream->fThresholdReached;
+                  pStream->szName, tsDeltaPlayedCapturedNs, tsDeltaPlayedCapturedNs / RT_NS_1MS_64,
+                  DrvAudioHlpFramesToMilli(cfLive, &pStream->Host.Cfg.Props),
+                  uLivePercent, cfLive, pStream->fThresholdReached));
+
+        bool fDoPlay      = pStream->fThresholdReached;
         bool fJustStarted = false;
         if (!fDoPlay)
         {
             /* Did we reach the backend's playback (pre-buffering) threshold? Can be 0 if no threshold set. */
-            if (cfLive >= pHstStream->Cfg.Backend.cfPreBuf)
+            if (cfLive >= pStream->Host.Cfg.Backend.cfPreBuf)
             {
-                LogRel2(("Audio: Stream '%s' buffering complete\n", pHstStream->szName));
+                LogRel2(("Audio: Stream '%s' buffering complete\n", pStream->szName));
                 fDoPlay = true;
             }
@@ -1628 +1486 @@
              * To reproduce, use "Windows Navigation Start.wav" on Windows 7 (2824 samples). */
             else if (   cfLive
-                     && pHstStream->fStatus & PDMAUDIOSTREAMSTS_FLAG_PENDING_DISABLE)
+                     && pStream->fStatus & PDMAUDIOSTREAMSTS_FLAG_PENDING_DISABLE)
             {
-                LogRel2(("Audio: Stream '%s' buffering complete (short sound)\n", pHstStream->szName));
+                LogRel2(("Audio: Stream '%s' buffering complete (short sound)\n", pStream->szName));
                 fDoPlay = true;
             }
@@ -1636 +1494 @@
             if (fDoPlay)
             {
-                pHstStream->fThresholdReached = true;
+                pStream->fThresholdReached = true;
                 fJustStarted = true;
-                LogRel2(("Audio: Stream '%s' started playing\n", pHstStream->szName));
+                LogRel2(("Audio: Stream '%s' started playing\n", pStream->szName));
             }
             else /* Not yet, so still buffering audio data. */
                 LogRel2(("Audio: Stream '%s' is buffering (%RU8%% complete)\n",
-                         pHstStream->szName, (100 * cfLive) / pHstStream->Cfg.Backend.cfPreBuf));
+                         pStream->szName, (100 * cfLive) / pStream->Host.Cfg.Backend.cfPreBuf));
         }
 
@@ -1649 +1507 @@
             uint32_t cfToPlay = 0;
             if (fJustStarted)
-                cfToPlay = pHstStream->Cfg.Backend.cfPeriod; /* cfPeriod can be 0. */
+                cfToPlay = pStream->Host.Cfg.Backend.cfPeriod; /* cfPeriod can be 0. */
 
             if (!cfToPlay)
             {
-                cfToPlay = DrvAudioHlpNanoToFrames(tsDeltaPlayedCapturedNs, &pHstStream->Cfg.Props);
-                if (pHstStream->Cfg.Device.uSchedulingHintMs)
-                    cfToPlay = RT_MIN(cfToPlay, DrvAudioHlpMilliToFrames(pHstStream->Cfg.Device.uSchedulingHintMs, &pHstStream->Cfg.Props));
+                cfToPlay = DrvAudioHlpNanoToFrames(tsDeltaPlayedCapturedNs, &pStream->Host.Cfg.Props);
+                if (pStream->Host.Cfg.Device.uSchedulingHintMs)
+                    cfToPlay = RT_MIN(cfToPlay, DrvAudioHlpMilliToFrames(pStream->Host.Cfg.Device.uSchedulingHintMs, &pStream->Host.Cfg.Props));
             }
 
             Log3Func(("[%s] Buffer: fJustStarted=%RTbool, cfLive=%RU32, cfToPlay=%RU32\n",
-                      pHstStream->szName, fJustStarted, cfLive, cfToPlay));
+                      pStream->szName, fJustStarted, cfLive, cfToPlay));
 
             /* Did we reach a buffer underrun? Do pre-buffering again.
              * If we're in pending disabled mode, try to play (drain) the remaining audio data. */
-            if (   !(pHstStream->fStatus & PDMAUDIOSTREAMSTS_FLAG_PENDING_DISABLE)
+            if (   !(pStream->fStatus & PDMAUDIOSTREAMSTS_FLAG_PENDING_DISABLE)
                 && !fJustStarted)
             {
                 if (cfLive < cfToPlay)
                 {
-                    pHstStream->fThresholdReached = false;
-                    Log3Func(("[%s] Buffer: Underrun (cfLive=%RU32, cfToPlay=%RU32)\n", pHstStream->szName, cfLive, cfToPlay));
+                    pStream->fThresholdReached = false;
+                    Log3Func(("[%s] Buffer: Underrun (cfLive=%RU32, cfToPlay=%RU32)\n", pStream->szName, cfLive, cfToPlay));
                     LogRel2(("Audio: Stream '%s' buffer underrun (total %RU8%%, which is %RU8%% of a period), buffering ...\n",
-                             pHstStream->szName, uLivePercent, (100 * cfLive) / pHstStream->Cfg.Backend.cfPeriod));
+                             pStream->szName, uLivePercent, (100 * cfLive) / pStream->Host.Cfg.Backend.cfPeriod));
                     break;
                 }
@@ -1683 +1541 @@
 #ifdef DEBUG
             if (!fJustStarted)
-                pHstStream->Out.Dbg.cbJitterWrittenPlayed -= AUDIOMIXBUF_F2B(&pHstStream->MixBuf, cfToPlay);
+                pStream->Out.Dbg.cbJitterWrittenPlayed -= AUDIOMIXBUF_F2B(&pStream->Host.MixBuf, cfToPlay);
             Log3Func(("[%s] Buffer: Playing %RU32 frames (%RU64ms), now filled with %RU64ms -- %RU8%% (cbJitterWrittenPlayed=%RI64)\n",
-                      pHstStream->szName, cfToPlay, DrvAudioHlpFramesToMilli(cfToPlay, &pHstStream->Cfg.Props),
-                      DrvAudioHlpFramesToMilli(AudioMixBufUsed(&pHstStream->MixBuf), &pHstStream->Cfg.Props),
-                      AudioMixBufUsed(&pHstStream->MixBuf) * 100 / AudioMixBufSize(&pHstStream->MixBuf),
-                      pHstStream->Out.Dbg.cbJitterWrittenPlayed));
+                      pStream->szName, cfToPlay, DrvAudioHlpFramesToMilli(cfToPlay, &pStream->Host.Cfg.Props),
+                      DrvAudioHlpFramesToMilli(AudioMixBufUsed(&pStream->Host.MixBuf), &pStream->Host.Cfg.Props),
+                      AudioMixBufUsed(&pStream->Host.MixBuf) * 100 / AudioMixBufSize(&pStream->Host.MixBuf),
+                      pStream->Out.Dbg.cbJitterWrittenPlayed));
 #endif
             if (pThis->pHostDrvAudio->pfnStreamPlayBegin)
-                pThis->pHostDrvAudio->pfnStreamPlayBegin(pThis->pHostDrvAudio, pHstStream->pvBackend);
-
-            if (RT_LIKELY(pHstStream->Cfg.enmLayout == PDMAUDIOSTREAMLAYOUT_NON_INTERLEAVED))
+                pThis->pHostDrvAudio->pfnStreamPlayBegin(pThis->pHostDrvAudio, pStream->pvBackend);
+
+            if (RT_LIKELY(pStream->Host.Cfg.enmLayout == PDMAUDIOSTREAMLAYOUT_NON_INTERLEAVED))
             {
-                rc = drvAudioStreamPlayNonInterleaved(pThis, pHstStream, cfToPlay, &cfPlayedTotal);
+                rc = drvAudioStreamPlayNonInterleaved(pThis, pStream, cfToPlay, &cfPlayedTotal);
             }
-            else if (pHstStream->Cfg.enmLayout == PDMAUDIOSTREAMLAYOUT_RAW)
+            else if (pStream->Host.Cfg.enmLayout == PDMAUDIOSTREAMLAYOUT_RAW)
             {
-                rc = drvAudioStreamPlayRaw(pThis, pHstStream, cfToPlay, &cfPlayedTotal);
+                rc = drvAudioStreamPlayRaw(pThis, pStream, cfToPlay, &cfPlayedTotal);
             }
             else
@@ -1705 +1563 @@
 
             if (pThis->pHostDrvAudio->pfnStreamPlayEnd)
-                pThis->pHostDrvAudio->pfnStreamPlayEnd(pThis->pHostDrvAudio, pHstStream->pvBackend);
+                pThis->pHostDrvAudio->pfnStreamPlayEnd(pThis->pHostDrvAudio, pStream->pvBackend);
         }
 
         if (RT_SUCCESS(rc))
         {
-            AudioMixBufFinish(&pHstStream->MixBuf, cfPlayedTotal);
+            AudioMixBufFinish(&pStream->Host.MixBuf, cfPlayedTotal);
 
 #ifdef VBOX_WITH_STATISTICS
             STAM_COUNTER_ADD     (&pThis->Stats.TotalFramesOut, cfPlayedTotal);
             STAM_PROFILE_ADV_STOP(&pThis->Stats.DelayOut, out);
-            STAM_COUNTER_ADD     (&pHstStream->Out.Stats.FramesPlayed, cfPlayedTotal);
+            STAM_COUNTER_ADD     (&pStream->Out.Stats.FramesPlayed, cfPlayedTotal);
 #endif
         }
@@ -1722 +1580 @@
 
 #ifdef LOG_ENABLED
-    uint32_t cfLive = AudioMixBufLive(&pHstStream->MixBuf);
-    pszStreamSts  = dbgAudioStreamStatusToStr(stsHstStream);
-    Log3Func(("[%s] Buffer: End stsHstStream=%s, cfLive=%RU32, cfPlayedTotal=%RU32, rc=%Rrc\n",
-              pHstStream->szName, pszStreamSts, cfLive, cfPlayedTotal, rc));
+    uint32_t cfLive = AudioMixBufLive(&pStream->Host.MixBuf);
+    pszStreamSts  = dbgAudioStreamStatusToStr(stsStream);
+    Log3Func(("[%s] Buffer: End fStatus=%s, cfLive=%RU32, cfPlayedTotal=%RU32, rc=%Rrc\n",
+              pStream->szName, pszStreamSts, cfLive, cfPlayedTotal, rc));
     RTStrFree(pszStreamSts);
 #endif /* LOG_ENABLED */
@@ -1750 +1608 @@
  * @returns IPRT status code.
  * @param   pThis               Driver instance.
- * @param   pHstStream          Host stream to capture from.
+ * @param   pStream             Stream to capture from.
  * @param   pcfCaptured         Number of (host) audio frames captured. Optional.
  */
-static int drvAudioStreamCaptureNonInterleaved(PDRVAUDIO pThis, PPDMAUDIOSTREAM pHstStream, uint32_t *pcfCaptured)
-{
-    AssertPtrReturn(pThis,      VERR_INVALID_POINTER);
-    AssertPtrReturn(pHstStream, VERR_INVALID_POINTER);
+static int drvAudioStreamCaptureNonInterleaved(PDRVAUDIO pThis, PPDMAUDIOSTREAM pStream, uint32_t *pcfCaptured)
+{
+    AssertPtrReturn(pThis,   VERR_INVALID_POINTER);
+    AssertPtrReturn(pStream, VERR_INVALID_POINTER);
     /* pcfCaptured is optional. */
 
     /* Sanity. */
-    Assert(pHstStream->enmCtx == PDMAUDIOSTREAMCTX_HOST);
-    Assert(pHstStream->enmDir == PDMAUDIODIR_IN);
-    Assert(pHstStream->Cfg.enmLayout == PDMAUDIOSTREAMLAYOUT_NON_INTERLEAVED);
+    Assert(pStream->enmDir == PDMAUDIODIR_IN);
+    Assert(pStream->Host.Cfg.enmLayout == PDMAUDIOSTREAMLAYOUT_NON_INTERLEAVED);
 
     int rc = VINF_SUCCESS;
@@ -1775 +1632 @@
     for (;;)
     {
-        uint32_t cbReadable = pThis->pHostDrvAudio->pfnStreamGetReadable(pThis->pHostDrvAudio, pHstStream->pvBackend);
+        uint32_t cbReadable = pThis->pHostDrvAudio->pfnStreamGetReadable(pThis->pHostDrvAudio, pStream->pvBackend);
         if (!cbReadable)
         {
-            Log2Func(("[%s] No readable data available, skipping\n", pHstStream->szName));
+            Log2Func(("[%s] No readable data available, skipping\n", pStream->szName));
             break;
         }
 
-        uint32_t cbFree = AUDIOMIXBUF_F2B(&pHstStream->MixBuf, AudioMixBufFree(&pHstStream->MixBuf));
+        uint32_t cbFree = AUDIOMIXBUF_F2B(&pStream->Host.MixBuf, AudioMixBufFree(&pStream->Host.MixBuf));
         if (!cbFree)
         {
-            Log2Func(("[%s] Host buffer full, skipping\n", pHstStream->szName));
+            Log2Func(("[%s] Host buffer full, skipping\n", pStream->szName));
             break;
         }
@@ -1798 +1655 @@
 
         uint32_t cbCaptured;
-        rc = pThis->pHostDrvAudio->pfnStreamCapture(pThis->pHostDrvAudio, pHstStream->pvBackend,
+        rc = pThis->pHostDrvAudio->pfnStreamCapture(pThis->pHostDrvAudio, pStream->pvBackend,
                                                     auBuf, cbFree, &cbCaptured);
         if (RT_FAILURE(rc))
         {
-            int rc2 = drvAudioStreamControlInternalBackend(pThis, pHstStream, PDMAUDIOSTREAMCMD_DISABLE);
+            int rc2 = drvAudioStreamControlInternalBackend(pThis, pStream, PDMAUDIOSTREAMCMD_DISABLE);
             AssertRC(rc2);
         }
@@ -1808 +1665 @@
         {
             if (pThis->In.Cfg.Dbg.fEnabled)
-                DrvAudioHlpFileWrite(pHstStream->In.Dbg.pFileCaptureNonInterleaved, auBuf, cbCaptured, 0 /* fFlags */);
+                DrvAudioHlpFileWrite(pStream->In.Dbg.pFileCaptureNonInterleaved, auBuf, cbCaptured, 0 /* fFlags */);
 
             Assert(cbCaptured <= cbBuf);
@@ -1815 +1672 @@
 
             uint32_t cfCaptured = 0;
-            rc = AudioMixBufWriteCirc(&pHstStream->MixBuf, auBuf, cbCaptured, &cfCaptured);
+            rc = AudioMixBufWriteCirc(&pStream->Host.MixBuf, auBuf, cbCaptured, &cfCaptured);
             if (RT_SUCCESS(rc))
                 cfCapturedTotal += cfCaptured;
@@ -1829 +1686 @@
     {
         if (cfCapturedTotal)
-            Log2Func(("[%s] %RU32 frames captured, rc=%Rrc\n", pHstStream->szName, cfCapturedTotal, rc));
+            Log2Func(("[%s] %RU32 frames captured, rc=%Rrc\n", pStream->szName, cfCapturedTotal, rc));
     }
     else
-        LogFunc(("[%s] Capturing failed with rc=%Rrc\n", pHstStream->szName, rc));
+        LogFunc(("[%s] Capturing failed with rc=%Rrc\n", pStream->szName, rc));
 
     if (pcfCaptured)
@@ -1849 +1706 @@
  * @returns IPRT status code.
  * @param   pThis               Driver instance.
- * @param   pHstStream          Host stream to capture from.
+ * @param   pStream             Stream to capture from.
  * @param   pcfCaptured         Number of (host) audio frames captured. Optional.
  */
-static int drvAudioStreamCaptureRaw(PDRVAUDIO pThis, PPDMAUDIOSTREAM pHstStream, uint32_t *pcfCaptured)
-{
-    AssertPtrReturn(pThis,      VERR_INVALID_POINTER);
-    AssertPtrReturn(pHstStream, VERR_INVALID_POINTER);
+static int drvAudioStreamCaptureRaw(PDRVAUDIO pThis, PPDMAUDIOSTREAM pStream, uint32_t *pcfCaptured)
+{
+    AssertPtrReturn(pThis,   VERR_INVALID_POINTER);
+    AssertPtrReturn(pStream, VERR_INVALID_POINTER);
     /* pcfCaptured is optional. */
 
     /* Sanity. */
-    Assert(pHstStream->enmCtx == PDMAUDIOSTREAMCTX_HOST);
-    Assert(pHstStream->enmDir == PDMAUDIODIR_IN);
-    Assert(pHstStream->Cfg.enmLayout == PDMAUDIOSTREAMLAYOUT_RAW);
+    Assert(pStream->enmDir == PDMAUDIODIR_IN);
+    Assert(pStream->Host.Cfg.enmLayout == PDMAUDIOSTREAMLAYOUT_RAW);
 
     int rc = VINF_SUCCESS;
@@ -1871 +1727 @@
     for (;;)
     {
-        uint32_t cbReadable = pThis->pHostDrvAudio->pfnStreamGetReadable(pThis->pHostDrvAudio, pHstStream->pvBackend);
+        uint32_t cbReadable = pThis->pHostDrvAudio->pfnStreamGetReadable(pThis->pHostDrvAudio, pStream->pvBackend);
         if (!cbReadable) /* Nothing to read on the backend side? Bail out. */
             break;
 
-        const uint32_t cbFree = AudioMixBufFreeBytes(&pHstStream->MixBuf);
+        const uint32_t cbFree = AudioMixBufFreeBytes(&pStream->Host.MixBuf);
         if (!cbFree) /* No space left in the host stream? */
             break;
@@ -1884 +1740 @@
         PPDMAUDIOFRAME paFrames;
         uint32_t cfWritable;
-        rc = AudioMixBufPeekMutable(&pHstStream->MixBuf, AUDIOMIXBUF_B2F(&pHstStream->MixBuf, cbReadable),
+        rc = AudioMixBufPeekMutable(&pStream->Host.MixBuf, AUDIOMIXBUF_B2F(&pStream->Host.MixBuf, cbReadable),
                                     &paFrames, &cfWritable);
         if (   RT_FAILURE(rc)
@@ -1893 +1749 @@
 
         uint32_t cfCaptured;
-        rc = pThis->pHostDrvAudio->pfnStreamCapture(pThis->pHostDrvAudio, pHstStream->pvBackend,
+        rc = pThis->pHostDrvAudio->pfnStreamCapture(pThis->pHostDrvAudio, pStream->pvBackend,
                                                     paFrames, cfWritable, &cfCaptured);
         if (RT_FAILURE(rc))
         {
-            int rc2 = drvAudioStreamControlInternalBackend(pThis, pHstStream, PDMAUDIOSTREAMCMD_DISABLE);
+            int rc2 = drvAudioStreamControlInternalBackend(pThis, pStream, PDMAUDIOSTREAMCMD_DISABLE);
             AssertRC(rc2);
         }
@@ -1915 +1771 @@
     }
 
-    Log2Func(("[%s] %RU32 frames captured, rc=%Rrc\n", pHstStream->szName, cfCapturedTotal, rc));
+    Log2Func(("[%s] %RU32 frames captured, rc=%Rrc\n", pStream->szName, cfCapturedTotal, rc));
 
     if (pcfCaptured)
@@ -1946 +1802 @@
             break;
 
-        PPDMAUDIOSTREAM pHstStream = drvAudioGetHostStream(pStream);
-        AssertPtr(pHstStream);
-        PPDMAUDIOSTREAM pGstStream = pHstStream ? pHstStream->pPair : NULL;
-        AssertPtr(pGstStream);
-
-        AssertReleaseMsgBreakStmt(pHstStream != NULL,
-                                  ("[%s] Host stream is NULL (cRefs=%RU32, fStatus=%x, enmCtx=%ld)\n",
-                                   pStream->szName, pStream->cRefs, pStream->fStatus, pStream->enmCtx),
-                                  rc = VERR_NOT_AVAILABLE);
-        AssertReleaseMsgBreakStmt(pGstStream != NULL,
-                                  ("[%s] Guest stream is NULL (cRefs=%RU32, fStatus=%x, enmCtx=%ld)\n",
-                                   pStream->szName, pStream->cRefs, pStream->fStatus, pStream->enmCtx),
-                                  rc = VERR_NOT_AVAILABLE);
-
         /*
          * Check if the backend is ready to operate.
          */
 
-        PDMAUDIOSTREAMSTS stsHstStream = pHstStream->fStatus;
+        PDMAUDIOSTREAMSTS stsStream = pStream->fStatus;
 #ifdef LOG_ENABLED
-        char *pszStreamSts = dbgAudioStreamStatusToStr(stsHstStream);
-        Log3Func(("[%s] Start: stsHstStream=%s\n", pHstStream->szName, pszStreamSts));
+        char *pszStreamSts = dbgAudioStreamStatusToStr(stsStream);
+        Log3Func(("[%s] Start: fStatus=%s\n", pStream->szName, pszStreamSts));
         RTStrFree(pszStreamSts);
 #endif /* LOG_ENABLED */
-        if (!(stsHstStream & PDMAUDIOSTREAMSTS_FLAG_ENABLED)) /* Stream disabled? Bail out. */
+        if (!(stsStream & PDMAUDIOSTREAMSTS_FLAG_ENABLED)) /* Stream disabled? Bail out. */
             break;
 
@@ -1978 +1820 @@
 
         if (pThis->pHostDrvAudio->pfnStreamCaptureBegin)
-            pThis->pHostDrvAudio->pfnStreamCaptureBegin(pThis->pHostDrvAudio, pHstStream->pvBackend);
-
-        if (RT_LIKELY(pHstStream->Cfg.enmLayout == PDMAUDIOSTREAMLAYOUT_NON_INTERLEAVED))
-        {
-            rc = drvAudioStreamCaptureNonInterleaved(pThis, pHstStream, &cfCaptured);
-        }
-        else if (pHstStream->Cfg.enmLayout == PDMAUDIOSTREAMLAYOUT_RAW)
-        {
-            rc = drvAudioStreamCaptureRaw(pThis, pHstStream, &cfCaptured);
+            pThis->pHostDrvAudio->pfnStreamCaptureBegin(pThis->pHostDrvAudio, pStream->pvBackend);
+
+        if (RT_LIKELY(pStream->Host.Cfg.enmLayout == PDMAUDIOSTREAMLAYOUT_NON_INTERLEAVED))
+        {
+            rc = drvAudioStreamCaptureNonInterleaved(pThis, pStream, &cfCaptured);
+        }
+        else if (pStream->Host.Cfg.enmLayout == PDMAUDIOSTREAMLAYOUT_RAW)
+        {
+            rc = drvAudioStreamCaptureRaw(pThis, pStream, &cfCaptured);
         }
         else
@@ -1992 +1834 @@
 
         if (pThis->pHostDrvAudio->pfnStreamCaptureEnd)
-            pThis->pHostDrvAudio->pfnStreamCaptureEnd(pThis->pHostDrvAudio, pHstStream->pvBackend);
+            pThis->pHostDrvAudio->pfnStreamCaptureEnd(pThis->pHostDrvAudio, pStream->pvBackend);
 
 #ifdef LOG_ENABLED
-        pszStreamSts = dbgAudioStreamStatusToStr(stsHstStream);
-        Log3Func(("[%s] End: stsHstStream=%s, cfCaptured=%RU32, rc=%Rrc\n",
-                  pHstStream->szName, pszStreamSts, cfCaptured, rc));
+        pszStreamSts = dbgAudioStreamStatusToStr(stsStream);
+        Log3Func(("[%s] End: fStatus=%s, cfCaptured=%RU32, rc=%Rrc\n",
+                  pStream->szName, pszStreamSts, cfCaptured, rc));
         RTStrFree(pszStreamSts);
 #endif /* LOG_ENABLED */
@@ -2003 +1845 @@
         if (RT_SUCCESS(rc))
         {
-            Log3Func(("[%s] %RU32 frames captured, rc=%Rrc\n", pHstStream->szName, cfCaptured, rc));
+            Log3Func(("[%s] %RU32 frames captured, rc=%Rrc\n", pStream->szName, cfCaptured, rc));
 
 #ifdef VBOX_WITH_STATISTICS
             STAM_COUNTER_ADD(&pThis->Stats.TotalFramesIn,        cfCaptured);
-            STAM_COUNTER_ADD(&pHstStream->In.Stats.FramesCaptured, cfCaptured);
+            STAM_COUNTER_ADD(&pStream->In.Stats.FramesCaptured, cfCaptured);
 #endif
         }
         else if (RT_UNLIKELY(RT_FAILURE(rc)))
         {
-            LogRel(("Audio: Capturing stream '%s' failed with %Rrc\n", pHstStream->szName, rc));
+            LogRel(("Audio: Capturing stream '%s' failed with %Rrc\n", pStream->szName, rc));
         }
 
@@ -2353 +2195 @@
     if (pThis->pHostDrvAudio)
     {
-        PPDMAUDIOSTREAM pHstStream;
-        RTListForEach(&pThis->lstHstStreams, pHstStream, PDMAUDIOSTREAM, Node)
-            drvAudioStreamControlInternalBackend(pThis, pHstStream, enmCmd);
+        PPDMAUDIOSTREAM pStream;
+        RTListForEach(&pThis->lstStreams, pStream, PDMAUDIOSTREAM, Node)
+            drvAudioStreamControlInternalBackend(pThis, pStream, enmCmd);
     }
 
@@ -2489 +2331 @@
         }
 
-        PPDMAUDIOSTREAM pHstStream = drvAudioGetHostStream(pStream);
-        if (!pHstStream)
-        {
-            rc = VERR_NOT_AVAILABLE;
-            break;
-        }
-
-        PPDMAUDIOSTREAM pGstStream = pHstStream->pPair;
-        AssertPtr(pGstStream);
-
         /*
          * Read from the parent buffer (that is, the guest buffer) which
@@ -2505 +2337 @@
         uint32_t cReadTotal = 0;
 
-        uint32_t cToRead = RT_MIN(AUDIOMIXBUF_B2F(&pGstStream->MixBuf, cbBuf), AudioMixBufUsed(&pGstStream->MixBuf));
-        while (cToRead)
+        uint32_t cfToRead = RT_MIN(AUDIOMIXBUF_B2F(&pStream->Guest.MixBuf, cbBuf), AudioMixBufUsed(&pStream->Guest.MixBuf));
+        while (cfToRead)
         {
             uint32_t cRead;
-            rc = AudioMixBufAcquireReadBlock(&pGstStream->MixBuf, (uint8_t *)pvBuf + AUDIOMIXBUF_F2B(&pGstStream->MixBuf, cReadTotal),
-                                             AUDIOMIXBUF_F2B(&pGstStream->MixBuf, cToRead), &cRead);
+            rc = AudioMixBufAcquireReadBlock(&pStream->Guest.MixBuf,
+                                             (uint8_t *)pvBuf + AUDIOMIXBUF_F2B(&pStream->Guest.MixBuf, cReadTotal),
+                                             AUDIOMIXBUF_F2B(&pStream->Guest.MixBuf, cfToRead), &cRead);
             if (RT_FAILURE(rc))
                 break;
 
 #ifdef VBOX_WITH_STATISTICS
-            const uint32_t cbRead = AUDIOMIXBUF_F2B(&pGstStream->MixBuf, cRead);
-
-            STAM_COUNTER_ADD(&pThis->Stats.TotalBytesRead,       cbRead);
-            STAM_COUNTER_ADD(&pGstStream->In.Stats.BytesTotalRead, cbRead);
+            const uint32_t cbRead = AUDIOMIXBUF_F2B(&pStream->Guest.MixBuf, cRead);
+
+            STAM_COUNTER_ADD(&pThis->Stats.TotalBytesRead,      cbRead);
+            STAM_COUNTER_ADD(&pStream->In.Stats.BytesTotalRead, cbRead);
 #endif
-            Assert(cToRead >= cRead);
-            cToRead -= cRead;
+            Assert(cfToRead >= cRead);
+            cfToRead -= cRead;
 
             cReadTotal += cRead;
 
-            AudioMixBufReleaseReadBlock(&pGstStream->MixBuf, cRead);
+            AudioMixBufReleaseReadBlock(&pStream->Guest.MixBuf, cRead);
         }
 
@@ -2531 +2364 @@
         {
             if (pThis->In.Cfg.Dbg.fEnabled)
-                DrvAudioHlpFileWrite(pHstStream->In.Dbg.pFileStreamRead,
-                                     pvBuf, AUDIOMIXBUF_F2B(&pGstStream->MixBuf, cReadTotal), 0 /* fFlags */);
-
-            AudioMixBufFinish(&pGstStream->MixBuf, cReadTotal);
-
-            cbReadTotal = AUDIOMIXBUF_F2B(&pGstStream->MixBuf, cReadTotal);
+                DrvAudioHlpFileWrite(pStream->In.Dbg.pFileStreamRead,
+                                     pvBuf, AUDIOMIXBUF_F2B(&pStream->Guest.MixBuf, cReadTotal), 0 /* fFlags */);
+
+            AudioMixBufFinish(&pStream->Guest.MixBuf, cReadTotal);
+
+            cbReadTotal = AUDIOMIXBUF_F2B(&pStream->Guest.MixBuf, cReadTotal);
         }
 
@@ -2580 +2413 @@
 #endif
 
-    /*
-     * The guest stream always will get the audio stream configuration told
-     * by the device emulation (which in turn was/could be set by the guest OS).
-     */
-    PPDMAUDIOSTREAM pGstStrm = NULL;
-
-    /** @todo Docs! */
-    PPDMAUDIOSTREAM pHstStrm = NULL;
+    PPDMAUDIOSTREAM pStream = NULL;
 
 #define RC_BREAK(x) { rc = x; break; }
@@ -2626 +2452 @@
         }
 
-        pHstStrm = (PPDMAUDIOSTREAM)RTMemAllocZ(sizeof(PDMAUDIOSTREAM));
-        AssertPtrBreakStmt(pHstStrm, rc = VERR_NO_MEMORY);
-
-        if (cbHstStrm) /* High unlikely that backends do not have an own space for data, but better check. */
-        {
-            pHstStrm->pvBackend = RTMemAllocZ(cbHstStrm);
-            AssertPtrBreakStmt(pHstStrm->pvBackend, rc = VERR_NO_MEMORY);
-
-            pHstStrm->cbBackend = cbHstStrm;
-        }
-
-        pHstStrm->enmCtx = PDMAUDIOSTREAMCTX_HOST;
-        pHstStrm->enmDir = pCfgHost->enmDir;
-
-        pGstStrm = (PPDMAUDIOSTREAM)RTMemAllocZ(sizeof(PDMAUDIOSTREAM));
-        AssertPtrBreakStmt(pGstStrm, rc = VERR_NO_MEMORY);
-
-        pGstStrm->enmCtx = PDMAUDIOSTREAMCTX_GUEST;
-        pGstStrm->enmDir = pCfgGuest->enmDir;
+        /*
+         * Allocate and initialize common state.
+         */
+
+        pStream = (PPDMAUDIOSTREAM)RTMemAllocZ(sizeof(PDMAUDIOSTREAM));
+        AssertPtrBreakStmt(pStream, rc = VERR_NO_MEMORY);
 
         /* Retrieve host driver name for easier identification. */
@@ -2660 +2473 @@
         }
 
+        RTStrPrintf(pStream->szName, RT_ELEMENTS(pStream->szName), "[%s] %s",
+                    szDriver, strlen(pCfgHost->szName) ? pCfgHost->szName : "<Untitled>");
+        pStream->enmDir = pCfgHost->enmDir;
+
         /*
-         * Init host stream.
+         * Allocate and init backend-specific data.
          */
-        RTStrPrintf(pHstStrm->szName, RT_ELEMENTS(pHstStrm->szName), "[%s] %s (Host)",
-                    szDriver, strlen(pCfgHost->szName) ? pCfgHost->szName : "<Untitled>");
-
-        rc = drvAudioStreamLinkToInternal(pHstStrm, pGstStrm);
-        AssertRCBreak(rc);
-
-        /*
-         * Init guest stream.
-         */
-        RTStrPrintf(pGstStrm->szName, RT_ELEMENTS(pGstStrm->szName), "[%s] %s (Guest)",
-                    szDriver, strlen(pCfgGuest->szName) ? pCfgGuest->szName : "<Untitled>");
-
-        pGstStrm->fStatus = pHstStrm->fStatus; /* Reflect the host stream's status. */
-
-        rc = drvAudioStreamLinkToInternal(pGstStrm, pHstStrm);
-        AssertRCBreak(rc);
+
+        if (cbHstStrm) /* High unlikely that backends do not have an own space for data, but better check. */
+        {
+            pStream->pvBackend = RTMemAllocZ(cbHstStrm);
+            AssertPtrBreakStmt(pStream->pvBackend, rc = VERR_NO_MEMORY);
+
+            pStream->cbBackend = cbHstStrm;
+        }
 
         /*
          * Try to init the rest.
          */
-        rc = drvAudioStreamInitInternal(pThis, pHstStrm, pCfgHost, pCfgGuest);
+
+        rc = drvAudioStreamInitInternal(pThis, pStream, pCfgHost, pCfgGuest);
         if (RT_FAILURE(rc))
             break;
 
-#ifdef VBOX_WITH_STATISTICS
-        char szStatName[255];
-
-        if (pCfgGuest->enmDir == PDMAUDIODIR_IN)
-        {
-            RTStrPrintf(szStatName, sizeof(szStatName), "Guest/%s/BytesElapsed", pGstStrm->szName);
-            PDMDrvHlpSTAMRegCounterEx(pThis->pDrvIns, &pGstStrm->In.Stats.BytesElapsed,
-                                      szStatName, STAMUNIT_BYTES, "Elapsed bytes read.");
-
-            RTStrPrintf(szStatName, sizeof(szStatName), "Guest/%s/BytesRead", pGstStrm->szName);
-            PDMDrvHlpSTAMRegCounterEx(pThis->pDrvIns, &pGstStrm->In.Stats.BytesTotalRead,
-                                      szStatName, STAMUNIT_BYTES, "Total bytes read.");
-
-            RTStrPrintf(szStatName, sizeof(szStatName), "Host/%s/FramesCaptured", pHstStrm->szName);
-            PDMDrvHlpSTAMRegCounterEx(pThis->pDrvIns, &pHstStrm->In.Stats.FramesCaptured,
-                                      szStatName, STAMUNIT_COUNT, "Total frames captured.");
-        }
-        else if (pCfgGuest->enmDir == PDMAUDIODIR_OUT)
-        {
-            RTStrPrintf(szStatName, sizeof(szStatName), "Guest/%s/BytesElapsed", pGstStrm->szName);
-            PDMDrvHlpSTAMRegCounterEx(pThis->pDrvIns, &pGstStrm->Out.Stats.BytesElapsed,
-                                      szStatName, STAMUNIT_BYTES, "Elapsed bytes written.");
-
-            RTStrPrintf(szStatName, sizeof(szStatName), "Guest/%s/BytesWritten", pGstStrm->szName);
-            PDMDrvHlpSTAMRegCounterEx(pThis->pDrvIns, &pGstStrm->Out.Stats.BytesTotalWritten,
-                                      szStatName, STAMUNIT_BYTES, "Total bytes written.");
-
-            RTStrPrintf(szStatName, sizeof(szStatName), "Host/%s/FramesPlayed", pHstStrm->szName);
-            PDMDrvHlpSTAMRegCounterEx(pThis->pDrvIns, &pHstStrm->Out.Stats.FramesPlayed,
-                                      szStatName, STAMUNIT_COUNT, "Total frames played.");
-        }
-        else
-            AssertFailed();
-#endif
-
     } while (0);
 
@@ -2728 +2503 @@
     if (RT_FAILURE(rc))
     {
-        if (pGstStrm)
-        {
-            int rc2 = drvAudioStreamUninitInternal(pThis, pGstStrm);
+        if (pStream)
+        {
+            int rc2 = drvAudioStreamUninitInternal(pThis, pStream);
             if (RT_SUCCESS(rc2))
             {
-                RTMemFree(pGstStrm);
-                pGstStrm = NULL;
+                drvAudioStreamFree(pStream);
+                pStream = NULL;
             }
         }
-
-        if (pHstStrm)
-        {
-            int rc2 = drvAudioStreamUninitInternal(pThis, pHstStrm);
-            if (RT_SUCCESS(rc2))
-            {
-                drvAudioStreamFree(pHstStrm);
-                pHstStrm = NULL;
-            }
-        }
     }
     else
     {
+        /* Append the stream to our stream list. */
+        RTListAppend(&pThis->lstStreams, &pStream->Node);
+
         /* Set initial reference counts. */
-        RTListAppend(&pThis->lstGstStreams, &pGstStrm->Node);
-        pGstStrm->cRefs = 1;
-
-        RTListAppend(&pThis->lstHstStreams, &pHstStrm->Node);
-        pHstStrm->cRefs = 1;
+        pStream->cRefs = 1;
 
         if (pCfgHost->enmDir == PDMAUDIODIR_IN)
@@ -2768 +2532 @@
                 {
                     rc2 = DrvAudioHlpFileCreate(PDMAUDIOFILETYPE_WAV, szFile, PDMAUDIOFILE_FLAG_NONE,
-                                                &pHstStrm->In.Dbg.pFileCaptureNonInterleaved);
+                                                &pStream->In.Dbg.pFileCaptureNonInterleaved);
                     if (RT_SUCCESS(rc2))
-                        rc2 = DrvAudioHlpFileOpen(pHstStrm->In.Dbg.pFileCaptureNonInterleaved, PDMAUDIOFILE_DEFAULT_OPEN_FLAGS,
-                                                  &pHstStrm->Cfg.Props);
+                        rc2 = DrvAudioHlpFileOpen(pStream->In.Dbg.pFileCaptureNonInterleaved, PDMAUDIOFILE_DEFAULT_OPEN_FLAGS,
+                                                  &pStream->Host.Cfg.Props);
                 }
 
@@ -2781 +2545 @@
                     {
                         rc2 = DrvAudioHlpFileCreate(PDMAUDIOFILETYPE_WAV, szFile, PDMAUDIOFILE_FLAG_NONE,
-                                                    &pHstStrm->In.Dbg.pFileStreamRead);
+                                                    &pStream->In.Dbg.pFileStreamRead);
                         if (RT_SUCCESS(rc2))
-                            rc2 = DrvAudioHlpFileOpen(pHstStrm->In.Dbg.pFileStreamRead, PDMAUDIOFILE_DEFAULT_OPEN_FLAGS,
-                                                      &pHstStrm->Cfg.Props);
+                            rc2 = DrvAudioHlpFileOpen(pStream->In.Dbg.pFileStreamRead, PDMAUDIOFILE_DEFAULT_OPEN_FLAGS,
+                                                      &pStream->Host.Cfg.Props);
                     }
                 }
@@ -2803 +2567 @@
                 {
                     rc2 = DrvAudioHlpFileCreate(PDMAUDIOFILETYPE_WAV, szFile, PDMAUDIOFILE_FLAG_NONE,
-                                                &pHstStrm->Out.Dbg.pFilePlayNonInterleaved);
+                                                &pStream->Out.Dbg.pFilePlayNonInterleaved);
                     if (RT_SUCCESS(rc2))
-                        rc = DrvAudioHlpFileOpen(pHstStrm->Out.Dbg.pFilePlayNonInterleaved, PDMAUDIOFILE_DEFAULT_OPEN_FLAGS,
-                                                 &pHstStrm->Cfg.Props);
+                        rc = DrvAudioHlpFileOpen(pStream->Out.Dbg.pFilePlayNonInterleaved, PDMAUDIOFILE_DEFAULT_OPEN_FLAGS,
+                                                 &pStream->Host.Cfg.Props);
                 }
 
@@ -2816 +2580 @@
                     {
                         rc2 = DrvAudioHlpFileCreate(PDMAUDIOFILETYPE_WAV, szFile, PDMAUDIOFILE_FLAG_NONE,
-                                                    &pHstStrm->Out.Dbg.pFileStreamWrite);
+                                                    &pStream->Out.Dbg.pFileStreamWrite);
                         if (RT_SUCCESS(rc2))
-                            rc2 = DrvAudioHlpFileOpen(pHstStrm->Out.Dbg.pFileStreamWrite, PDMAUDIOFILE_DEFAULT_OPEN_FLAGS,
-                                                      &pHstStrm->Cfg.Props);
+                            rc2 = DrvAudioHlpFileOpen(pStream->Out.Dbg.pFileStreamWrite, PDMAUDIOFILE_DEFAULT_OPEN_FLAGS,
+                                                      &pStream->Host.Cfg.Props);
                     }
                 }
@@ -2831 +2595 @@
         STAM_COUNTER_ADD(&pThis->Stats.TotalStreamsCreated, 1);
 #endif
-        /* Always return the guest-side part to the device emulation. */
-        *ppStream = pGstStrm;
+        *ppStream = pStream;
     }
 
@@ -2870 +2633 @@
 
         PPDMAUDIOSTREAM pStream;
-        RTListForEach(&pThis->lstHstStreams, pStream, PDMAUDIOSTREAM, Node)
+        RTListForEach(&pThis->lstStreams, pStream, PDMAUDIOSTREAM, Node)
         {
             if (pStream->enmDir != enmDir) /* Skip unwanted streams. */
@@ -3005 +2768 @@
     AssertMsg(pStream->enmDir == PDMAUDIODIR_IN, ("Can't read from a non-input stream\n"));
 
-    PPDMAUDIOSTREAM pHstStream = drvAudioGetHostStream(pStream);
-    if (!pHstStream) /* No host stream available? Bail out early. */
-    {
-        rc2 = RTCritSectLeave(&pThis->CritSect);
-        AssertRC(rc2);
-
-        return 0;
-    }
-
-    uint32_t cbReadable = 0;
-
-    PPDMAUDIOSTREAM pGstStream = pHstStream->pPair;
-    if (pGstStream)
-    {
-        uint32_t cfReadable = AudioMixBufLive(&pGstStream->MixBuf);
-
-        Log3Func(("[%s] cfReadable=%RU32 (%zu bytes)\n", pHstStream->szName, cfReadable,
-                  AUDIOMIXBUF_F2B(&pGstStream->MixBuf, cfReadable)));
-
-        cbReadable = AUDIOMIXBUF_F2B(&pGstStream->MixBuf, cfReadable);
-    }
+    const uint32_t cfReadable = AudioMixBufLive(&pStream->Guest.MixBuf);
+
+    Log3Func(("[%s] cfReadable=%RU32 (%zu bytes)\n", pStream->szName, cfReadable,
+              AUDIOMIXBUF_F2B(&pStream->Guest.MixBuf, cfReadable)));
+
+    uint32_t cbReadable = AUDIOMIXBUF_F2B(&pStream->Guest.MixBuf, cfReadable);
 
     rc2 = RTCritSectLeave(&pThis->CritSect);
@@ -3049 +2797 @@
     AssertMsg(pStream->enmDir == PDMAUDIODIR_OUT, ("Can't write to a non-output stream\n"));
 
-    PPDMAUDIOSTREAM pHstStream = drvAudioGetHostStream(pStream);
-    if (!pHstStream) /* No host stream available? Bail out early. */
-    {
-        rc2 = RTCritSectLeave(&pThis->CritSect);
-        AssertRC(rc2);
-
-        AssertMsgFailed(("Guest stream '%s' does not have a host stream attached\n", pStream->szName));
-        return 0;
-    }
-
     /* As the host side sets the overall pace, return the writable bytes from that side. */
-    const uint64_t deltaLastReadWriteNs = RTTimeNanoTS() - pHstStream->tsLastReadWrittenNs;
+    const uint64_t deltaLastReadWriteNs = RTTimeNanoTS() - pStream->tsLastReadWrittenNs;
 
     uint32_t cbWritable = 0;
 
-    if (DrvAudioHlpStreamStatusCanWrite(pHstStream->fStatus))
-    {
-        cbWritable = DrvAudioHlpNanoToBytes(deltaLastReadWriteNs, &pHstStream->Cfg.Props);
-
-        /* Make sure to align the writable size to the stream's frame size. */
-        cbWritable = DrvAudioHlpBytesAlign(cbWritable, &pHstStream->Cfg.Props);
-    }
-
-    Log3Func(("[%s] cbWritable=%RU32 (%RU64ms)\n", pHstStream->szName, cbWritable, deltaLastReadWriteNs / RT_NS_1MS_64));
+    if (DrvAudioHlpStreamStatusCanWrite(pStream->fStatus))
+    {
+        cbWritable = DrvAudioHlpNanoToBytes(deltaLastReadWriteNs, &pStream->Host.Cfg.Props);
+
+        /* Make sure to align the writable size to the guest's frame size. */
+        cbWritable = DrvAudioHlpBytesAlign(cbWritable, &pStream->Guest.Cfg.Props);
+    }
+
+    Log3Func(("[%s] cbWritable=%RU32 (%RU64ms)\n", pStream->szName, cbWritable, deltaLastReadWriteNs / RT_NS_1MS_64));
 
     rc2 = RTCritSectLeave(&pThis->CritSect);
@@ -3095 +2833 @@
     AssertRC(rc2);
 
-    PDMAUDIOSTREAMSTS stsStream = PDMAUDIOSTREAMSTS_FLAG_NONE;
-
-    PPDMAUDIOSTREAM pHstStream = drvAudioGetHostStream(pStream);
-    if (pHstStream)
-    {
-        /* If the connector is ready to operate, also make sure to ask the backend. */
-        stsStream = pHstStream->fStatus;
-        if (DrvAudioHlpStreamStatusIsReady(stsStream))
-            stsStream = pThis->pHostDrvAudio->pfnStreamGetStatus(pThis->pHostDrvAudio, pHstStream->pvBackend);
+    /* If the connector is ready to operate, also make sure to ask the backend. */
+    PDMAUDIOSTREAMSTS stsStream = pStream->fStatus;
+    if (DrvAudioHlpStreamStatusIsReady(stsStream))
+        stsStream = pThis->pHostDrvAudio->pfnStreamGetStatus(pThis->pHostDrvAudio, pStream->pvBackend);
 
 #ifdef LOG_ENABLED
-        char *pszStreamSts = dbgAudioStreamStatusToStr(stsStream);
-        Log3Func(("[%s] %s\n", pHstStream->szName, pszStreamSts));
-        RTStrFree(pszStreamSts);
+    char *pszStreamSts = dbgAudioStreamStatusToStr(stsStream);
+    Log3Func(("[%s] %s\n", pStream->szName, pszStreamSts));
+    RTStrFree(pszStreamSts);
 #endif
-    }
 
     rc2 = RTCritSectLeave(&pThis->CritSect);
@@ -3129 +2861 @@
     LogFlowFunc(("[%s] volL=%RU32, volR=%RU32, fMute=%RTbool\n", pStream->szName, pVol->uLeft, pVol->uRight, pVol->fMuted));
 
-    PPDMAUDIOSTREAM pHstStream = drvAudioGetHostStream(pStream);
-    PPDMAUDIOSTREAM pGstStream = pHstStream ? pHstStream->pPair : pStream;
-
-    AudioMixBufSetVolume(&pHstStream->MixBuf, pVol);
-    AudioMixBufSetVolume(&pGstStream->MixBuf, pVol);
+    AudioMixBufSetVolume(&pStream->Guest.MixBuf, pVol);
+    AudioMixBufSetVolume(&pStream->Host.MixBuf, pVol);
+
     return VINF_SUCCESS;
 }
@@ -3150 +2880 @@
     AssertRC(rc);
 
-    PDMAUDIODIR enmDir = pStream->enmDir;
+    LogRel2(("Audio: Destroying stream '%s'\n", pStream->szName));
 
     LogFlowFunc(("[%s] cRefs=%RU32\n", pStream->szName, pStream->cRefs));
@@ -3158 +2888 @@
     if (RT_SUCCESS(rc))
     {
-        PPDMAUDIOSTREAM pHstStream = drvAudioGetHostStream(pStream);
-        PPDMAUDIOSTREAM pGstStream = pHstStream ? pHstStream->pPair : pStream;
-
-        LogRel2(("Audio: Destroying host stream '%s' (guest stream '%s')\n",
-                 pHstStream ? pHstStream->szName : "<None>",
-                 pGstStream ? pGstStream->szName : "<None>"));
-
-        /* Should prevent double frees. */
-        Assert(pHstStream != pGstStream);
-
-        if (pHstStream)
-        {
-            rc = drvAudioStreamUninitInternal(pThis, pHstStream);
-            if (RT_SUCCESS(rc))
-            {
-                if (pHstStream->enmDir == PDMAUDIODIR_IN)
-                {
-#ifdef VBOX_WITH_STATISTICS
-                    PDMDrvHlpSTAMDeregister(pThis->pDrvIns, &pHstStream->In.Stats.FramesCaptured);
-#endif
-                    if (pThis->In.Cfg.Dbg.fEnabled)
-                    {
-                        DrvAudioHlpFileDestroy(pHstStream->In.Dbg.pFileCaptureNonInterleaved);
-                        DrvAudioHlpFileDestroy(pHstStream->In.Dbg.pFileStreamRead);
-                    }
-                }
-                else if (pHstStream->enmDir == PDMAUDIODIR_OUT)
-                {
-#ifdef VBOX_WITH_STATISTICS
-                    PDMDrvHlpSTAMDeregister(pThis->pDrvIns, &pHstStream->Out.Stats.FramesPlayed);
-#endif
-                    if (pThis->Out.Cfg.Dbg.fEnabled)
-                    {
-                        DrvAudioHlpFileDestroy(pHstStream->Out.Dbg.pFilePlayNonInterleaved);
-                        DrvAudioHlpFileDestroy(pHstStream->Out.Dbg.pFileStreamWrite);
-                    }
-                }
-                else
-                    AssertFailed();
-
-                RTListNodeRemove(&pHstStream->Node);
-
-                drvAudioStreamFree(pHstStream);
-                pHstStream = NULL;
-            }
-            else
-                LogRel(("Audio: Uninitializing host stream '%s' failed with %Rrc\n", pHstStream->szName, rc));
-        }
-
-        if (   RT_SUCCESS(rc)
-            && pGstStream)
-        {
-            rc = drvAudioStreamUninitInternal(pThis, pGstStream);
-            if (RT_SUCCESS(rc))
-            {
-#ifdef VBOX_WITH_STATISTICS
-                if (pGstStream->enmDir == PDMAUDIODIR_IN)
-                {
-                    PDMDrvHlpSTAMDeregister(pThis->pDrvIns, &pGstStream->In.Stats.BytesElapsed);
-                    PDMDrvHlpSTAMDeregister(pThis->pDrvIns, &pGstStream->In.Stats.BytesTotalRead);
-                    PDMDrvHlpSTAMDeregister(pThis->pDrvIns, &pGstStream->In.Stats.FramesCaptured);
-                }
-                else if (pGstStream->enmDir == PDMAUDIODIR_OUT)
-                {
-                    PDMDrvHlpSTAMDeregister(pThis->pDrvIns, &pGstStream->Out.Stats.BytesElapsed);
-                    PDMDrvHlpSTAMDeregister(pThis->pDrvIns, &pGstStream->Out.Stats.BytesTotalWritten);
-                    PDMDrvHlpSTAMDeregister(pThis->pDrvIns, &pGstStream->Out.Stats.FramesPlayed);
-                }
-                else
-                    AssertFailed();
-#endif
-                RTListNodeRemove(&pGstStream->Node);
-
-                RTMemFree(pGstStream);
-                pGstStream = NULL;
-            }
-            else
-                LogRel(("Audio: Uninitializing guest stream '%s' failed with %Rrc\n", pGstStream->szName, rc));
-        }
+        rc = drvAudioStreamUninitInternal(pThis, pStream);
+        if (RT_FAILURE(rc))
+            LogRel(("Audio: Uninitializing stream '%s' failed with %Rrc\n", pStream->szName, rc));
     }
 
     if (RT_SUCCESS(rc))
     {
-        if (enmDir == PDMAUDIODIR_IN)
+        if (pStream->enmDir == PDMAUDIODIR_IN)
         {
             pThis->In.cStreamsFree++;
@@ -3249 +2903 @@
             pThis->Out.cStreamsFree++;
         }
+
+        RTListNodeRemove(&pStream->Node);
+
+        drvAudioStreamFree(pStream);
+        pStream = NULL;
     }
 
@@ -3264 +2923 @@
  * @returns IPRT status code.
  * @param   pThis               Pointer to driver instance.
- * @param   pHstStream          (Host) audio stream to use for creating the stream on the backend side.
+ * @param   pStream             Audio stream to create the backend side for.
  * @param   pCfgReq             Requested audio stream configuration to use for stream creation.
  * @param   pCfgAcq             Acquired audio stream configuration returned by the backend.
  */
 static int drvAudioStreamCreateInternalBackend(PDRVAUDIO pThis,
-                                               PPDMAUDIOSTREAM pHstStream, PPDMAUDIOSTREAMCFG pCfgReq, PPDMAUDIOSTREAMCFG pCfgAcq)
-{
-    AssertPtrReturn(pThis,      VERR_INVALID_POINTER);
-    AssertPtrReturn(pHstStream, VERR_INVALID_POINTER);
-    AssertPtrReturn(pCfgReq,    VERR_INVALID_POINTER);
-    AssertPtrReturn(pCfgAcq,    VERR_INVALID_POINTER);
-
-    AssertMsg(pHstStream->enmCtx == PDMAUDIOSTREAMCTX_HOST,
-              ("Stream '%s' is not a host stream and therefore has no backend\n", pHstStream->szName));
-
-    AssertMsg((pHstStream->fStatus & PDMAUDIOSTREAMSTS_FLAG_INITIALIZED) == 0,
-              ("Stream '%s' already initialized in backend\n", pHstStream->szName));
+                                               PPDMAUDIOSTREAM pStream, PPDMAUDIOSTREAMCFG pCfgReq, PPDMAUDIOSTREAMCFG pCfgAcq)
+{
+    AssertPtrReturn(pThis,   VERR_INVALID_POINTER);
+    AssertPtrReturn(pStream, VERR_INVALID_POINTER);
+    AssertPtrReturn(pCfgReq, VERR_INVALID_POINTER);
+    AssertPtrReturn(pCfgAcq, VERR_INVALID_POINTER);
+
+    AssertMsg((pStream->fStatus & PDMAUDIOSTREAMSTS_FLAG_INITIALIZED) == 0,
+              ("Stream '%s' already initialized in backend\n", pStream->szName));
 
     /* Get the right configuration for the stream to be created. */
@@ -3298 +2954 @@
     LogRel2(("Audio: Using %s period size (%RU32ms, %RU32 frames) for stream '%s'\n",
              pDrvCfg->uPeriodMs ? "custom" : "default", DrvAudioHlpFramesToMilli(pCfgReq->Backend.cfPeriod, &pCfgReq->Props),
-             pCfgReq->Backend.cfPeriod, pHstStream->szName));
+             pCfgReq->Backend.cfPeriod, pStream->szName));
 
     /*
@@ -3310 +2966 @@
     LogRel2(("Audio: Using %s buffer size (%RU32ms, %RU32 frames) for stream '%s'\n",
              pDrvCfg->uBufferSizeMs ? "custom" : "default", DrvAudioHlpFramesToMilli(pCfgReq->Backend.cfBufferSize, &pCfgReq->Props),
-             pCfgReq->Backend.cfBufferSize, pHstStream->szName));
+             pCfgReq->Backend.cfBufferSize, pStream->szName));
 
     /*
@@ -3318 +2974 @@
     {
         if (!pDrvCfg->uPreBufMs) /* Pre-buffering is set to disabled. */
-            LogRel2(("Audio: Using custom pre-buffering (disabled) for stream '%s'\n", pHstStream->szName));
+            LogRel2(("Audio: Using custom pre-buffering (disabled) for stream '%s'\n", pStream->szName));
         pCfgReq->Backend.cfPreBuf = DrvAudioHlpMilliToFrames(pDrvCfg->uPreBufMs, &pCfgReq->Props);
     }
@@ -3326 +2982 @@
     LogRel2(("Audio: Using %s pre-buffering size (%RU32ms, %RU32 frames) for stream '%s'\n",
              pDrvCfg->uPreBufMs != UINT32_MAX ? "custom" : "default", DrvAudioHlpFramesToMilli(pCfgReq->Backend.cfPreBuf, &pCfgReq->Props),
-             pCfgReq->Backend.cfPreBuf, pHstStream->szName));
+             pCfgReq->Backend.cfPreBuf, pStream->szName));
 
     /*
@@ -3334 +2990 @@
     {
         LogRel(("Audio: Error for stream '%s': Buffer size (%RU32ms) must not be smaller than the period size (%RU32ms)\n",
-                pHstStream->szName, DrvAudioHlpFramesToMilli(pCfgReq->Backend.cfBufferSize, &pCfgReq->Props),
+                pStream->szName, DrvAudioHlpFramesToMilli(pCfgReq->Backend.cfBufferSize, &pCfgReq->Props),
                 DrvAudioHlpFramesToMilli(pCfgReq->Backend.cfPeriod, &pCfgReq->Props)));
         return VERR_INVALID_PARAMETER;
@@ -3345 +3001 @@
         {
             LogRel(("Audio: Error for stream '%s': Pre-buffering size (%RU32ms) must not be bigger than the buffer size (%RU32ms)\n",
-                    pHstStream->szName, DrvAudioHlpFramesToMilli(pCfgReq->Backend.cfPreBuf, &pCfgReq->Props),
+                    pStream->szName, DrvAudioHlpFramesToMilli(pCfgReq->Backend.cfPreBuf, &pCfgReq->Props),
                     DrvAudioHlpFramesToMilli(pCfgReq->Backend.cfBufferSize, &pCfgReq->Props)));
             return VERR_INVALID_PARAMETER;
@@ -3357 +3013 @@
     {
         LogRel(("Audio: Creating stream '%s' with an invalid backend configuration not possible, skipping\n",
-                pHstStream->szName));
+                pStream->szName));
         return rc;
     }
 
-    rc = pThis->pHostDrvAudio->pfnStreamCreate(pThis->pHostDrvAudio, pHstStream->pvBackend, pCfgReq, pCfgAcq);
+    rc = pThis->pHostDrvAudio->pfnStreamCreate(pThis->pHostDrvAudio, pStream->pvBackend, pCfgReq, pCfgAcq);
     if (RT_FAILURE(rc))
     {
         if (rc == VERR_NOT_SUPPORTED)
-            LogRel2(("Audio: Creating stream '%s' in backend not supported, skipping\n", pHstStream->szName));
+            LogRel2(("Audio: Creating stream '%s' in backend not supported, skipping\n", pStream->szName));
         else
-            LogRel(("Audio: Creating stream '%s' in backend failed with %Rrc\n", pHstStream->szName, rc));
+            LogRel(("Audio: Creating stream '%s' in backend failed with %Rrc\n", pStream->szName, rc));
 
         return rc;
@@ -3375 +3031 @@
     if (!DrvAudioHlpStreamCfgIsValid(pCfgAcq))
     {
-        LogRel(("Audio: Creating stream '%s' returned an invalid backend configuration, skipping\n", pHstStream->szName));
+        LogRel(("Audio: Creating stream '%s' returned an invalid backend configuration, skipping\n", pStream->szName));
         return VERR_INVALID_PARAMETER;
     }
@@ -3384 +3040 @@
     {
         LogRel2(("Audio: Custom buffer size overwritten by backend for stream '%s' (now %RU64ms, %RU32 frames)\n",
-                 pHstStream->szName, DrvAudioHlpFramesToMilli(pCfgAcq->Backend.cfBufferSize, &pCfgAcq->Props), pCfgAcq->Backend.cfBufferSize));
+                 pStream->szName, DrvAudioHlpFramesToMilli(pCfgAcq->Backend.cfBufferSize, &pCfgAcq->Props), pCfgAcq->Backend.cfBufferSize));
     }
 
@@ -3391 +3047 @@
     {
         LogRel2(("Audio: Custom period size overwritten by backend for stream '%s' (now %RU64ms, %RU32 frames)\n",
-                 pHstStream->szName, DrvAudioHlpFramesToMilli(pCfgAcq->Backend.cfPeriod, &pCfgAcq->Props), pCfgAcq->Backend.cfPeriod));
+                 pStream->szName, DrvAudioHlpFramesToMilli(pCfgAcq->Backend.cfPeriod, &pCfgAcq->Props), pCfgAcq->Backend.cfPeriod));
     }
 
@@ -3398 +3054 @@
     {
         LogRel2(("Audio: Custom pre-buffering size overwritten by backend for stream '%s' (now %RU64ms, %RU32 frames)\n",
-                 pHstStream->szName, DrvAudioHlpFramesToMilli(pCfgAcq->Backend.cfPreBuf, &pCfgAcq->Props), pCfgAcq->Backend.cfPreBuf));
-    }
-
-    /* Only set the host's stream to initialized if we were able create the stream
-     * in the host backend. This is necessary for trying to re-initialize the stream
-     * at some later point in time. */
-    pHstStream->fStatus |= PDMAUDIOSTREAMSTS_FLAG_INITIALIZED;
+                 pStream->szName, DrvAudioHlpFramesToMilli(pCfgAcq->Backend.cfPreBuf, &pCfgAcq->Props), pCfgAcq->Backend.cfPreBuf));
+    }
+
+    pStream->fStatus |= PDMAUDIOSTREAMSTS_FLAG_INITIALIZED;
 
     return VINF_SUCCESS;
@@ -3414 +3067 @@
  * @returns IPRT status code.
  * @param   pThis               Pointer to driver instance.
- * @param   pHstStream          Host audio stream to call the backend destruction for.
- */
-static int drvAudioStreamDestroyInternalBackend(PDRVAUDIO pThis, PPDMAUDIOSTREAM pHstStream)
-{
-    AssertPtrReturn(pThis,      VERR_INVALID_POINTER);
-    AssertPtrReturn(pHstStream, VERR_INVALID_POINTER);
-
-    AssertMsg(pHstStream->enmCtx == PDMAUDIOSTREAMCTX_HOST,
-              ("Stream '%s' is not a host stream and therefore has no backend\n", pHstStream->szName));
+ * @param   pStream             Audio stream destruct backend for.
+ */
+static int drvAudioStreamDestroyInternalBackend(PDRVAUDIO pThis, PPDMAUDIOSTREAM pStream)
+{
+    AssertPtrReturn(pThis,   VERR_INVALID_POINTER);
+    AssertPtrReturn(pStream, VERR_INVALID_POINTER);
 
     int rc = VINF_SUCCESS;
 
 #ifdef LOG_ENABLED
-    char *pszHstSts = dbgAudioStreamStatusToStr(pHstStream->fStatus);
-    LogFunc(("[%s] fStatus=%s\n", pHstStream->szName, pszHstSts));
-    RTStrFree(pszHstSts);
+    char *pszStreamSts = dbgAudioStreamStatusToStr(pStream->fStatus);
+    LogFunc(("[%s] fStatus=%s\n", pStream->szName, pszStreamSts));
 #endif
 
-    if (pHstStream->fStatus & PDMAUDIOSTREAMSTS_FLAG_INITIALIZED)
+    if (pStream->pvBackend)
     {
         /* Check if the pointer to  the host audio driver is still valid.
          * It can be NULL if we were called in drvAudioDestruct, for example. */
         if (pThis->pHostDrvAudio)
-            rc = pThis->pHostDrvAudio->pfnStreamDestroy(pThis->pHostDrvAudio, pHstStream->pvBackend);
-        if (RT_SUCCESS(rc))
-        {
-            pHstStream->fStatus &= ~PDMAUDIOSTREAMSTS_FLAG_INITIALIZED;
+            rc = pThis->pHostDrvAudio->pfnStreamDestroy(pThis->pHostDrvAudio, pStream->pvBackend);
+
+        pStream->pvBackend = NULL;
+        pStream->cbBackend = 0;
+    }
 
 #ifdef LOG_ENABLED
-            /* This is not fatal, but log it anyway. */
-            if (pHstStream->fStatus != PDMAUDIOSTREAMSTS_FLAG_NONE)
-                LogFunc(("[%s] Warning: Stream still has %s set when destroying, must properly drain first\n",
-                         pHstStream->szName, pszHstSts));
+    RTStrFree(pszStreamSts);
 #endif
-        }
-    }
-
-    LogFlowFunc(("[%s] Returning %Rrc\n", pHstStream->szName, rc));
+
+    LogFlowFunc(("[%s] Returning %Rrc\n", pStream->szName, rc));
     return rc;
 }
@@ -3472 +3117 @@
         return VERR_WRONG_ORDER;
 
-    int rc = VINF_SUCCESS;
-
-    if (pStream->enmCtx == PDMAUDIOSTREAMCTX_GUEST)
-    {
-        if (pStream->fStatus & PDMAUDIOSTREAMSTS_FLAG_INITIALIZED)
-        {
-            rc = drvAudioStreamControlInternal(pThis, pStream, PDMAUDIOSTREAMCMD_DISABLE);
-            if (RT_SUCCESS(rc))
-            {
-                pStream->fStatus &= ~PDMAUDIOSTREAMSTS_FLAG_INITIALIZED;
-                Assert(pStream->fStatus == PDMAUDIOSTREAMSTS_FLAG_NONE);
-            }
-        }
-    }
-    else if (pStream->enmCtx == PDMAUDIOSTREAMCTX_HOST)
-    {
+    int rc = drvAudioStreamControlInternal(pThis, pStream, PDMAUDIOSTREAMCMD_DISABLE);
+    if (RT_SUCCESS(rc))
         rc = drvAudioStreamDestroyInternalBackend(pThis, pStream);
+
+    /* Destroy mixing buffers. */
+    AudioMixBufDestroy(&pStream->Guest.MixBuf);
+    AudioMixBufDestroy(&pStream->Host.MixBuf);
+
+    if (RT_SUCCESS(rc))
+    {
+        /* Reset status. */
+        pStream->fStatus &= ~PDMAUDIOSTREAMSTS_FLAG_INITIALIZED;
+
+#ifdef VBOX_STRICT
+        if (pStream->fStatus != PDMAUDIOSTREAMSTS_FLAG_NONE)
+        {
+            char *pszStreamSts = dbgAudioStreamStatusToStr(pStream->fStatus);
+            LogFunc(("[%s] Warning: Still has %s set when uninitializing\n", pStream->szName, pszStreamSts));
+            RTStrFree(pszStreamSts);
+        }
+#endif
+        pStream->fStatus = PDMAUDIOSTREAMSTS_FLAG_NONE;
+    }
+
+    if (pStream->enmDir == PDMAUDIODIR_IN)
+    {
+#ifdef VBOX_WITH_STATISTICS
+        PDMDrvHlpSTAMDeregister(pThis->pDrvIns, &pStream->In.Stats.BytesElapsed);
+        PDMDrvHlpSTAMDeregister(pThis->pDrvIns, &pStream->In.Stats.BytesTotalRead);
+        PDMDrvHlpSTAMDeregister(pThis->pDrvIns, &pStream->In.Stats.FramesCaptured);
+#endif
+        if (pThis->In.Cfg.Dbg.fEnabled)
+        {
+            DrvAudioHlpFileDestroy(pStream->In.Dbg.pFileCaptureNonInterleaved);
+            pStream->In.Dbg.pFileCaptureNonInterleaved = NULL;
+
+            DrvAudioHlpFileDestroy(pStream->In.Dbg.pFileStreamRead);
+            pStream->In.Dbg.pFileStreamRead = NULL;
+        }
+    }
+    else if (pStream->enmDir == PDMAUDIODIR_OUT)
+    {
+#ifdef VBOX_WITH_STATISTICS
+        PDMDrvHlpSTAMDeregister(pThis->pDrvIns, &pStream->Out.Stats.BytesElapsed);
+        PDMDrvHlpSTAMDeregister(pThis->pDrvIns, &pStream->Out.Stats.BytesTotalWritten);
+        PDMDrvHlpSTAMDeregister(pThis->pDrvIns, &pStream->Out.Stats.FramesPlayed);
+#endif
+        if (pThis->Out.Cfg.Dbg.fEnabled)
+        {
+            DrvAudioHlpFileDestroy(pStream->Out.Dbg.pFilePlayNonInterleaved);
+            pStream->Out.Dbg.pFilePlayNonInterleaved = NULL;
+
+            DrvAudioHlpFileDestroy(pStream->Out.Dbg.pFileStreamWrite);
+            pStream->Out.Dbg.pFileStreamWrite = NULL;
+        }
     }
     else
-        AssertFailedReturn(VERR_NOT_IMPLEMENTED);
-
-    if (RT_SUCCESS(rc))
-    {
-        /* Make sure that the pair (if any) knows that we're not valid anymore. */
-        int rc2 = drvAudioStreamLinkToInternal(pStream, NULL);
-        AssertRC(rc2);
-
-        /* Reset status. */
-        pStream->fStatus = PDMAUDIOSTREAMSTS_FLAG_NONE;
-
-        /* Destroy mixing buffer. */
-        AudioMixBufDestroy(&pStream->MixBuf);
-    }
+        AssertFailed();
 
     LogFlowFunc(("Returning %Rrc\n", rc));
@@ -3587 +3257 @@
      * in drvAudioDestruct(). */
     PPDMAUDIOSTREAM pStream;
-    RTListForEach(&pThis->lstHstStreams, pStream, PDMAUDIOSTREAM, Node)
+    RTListForEach(&pThis->lstStreams, pStream, PDMAUDIOSTREAM, Node)
     {
         drvAudioStreamControlInternalBackend(pThis, pStream, PDMAUDIOSTREAMCMD_DISABLE);
@@ -3617 +3287 @@
     PDMDRV_CHECK_VERSIONS_RETURN(pDrvIns);
 
-    RTListInit(&pThis->lstHstStreams);
-    RTListInit(&pThis->lstGstStreams);
+    RTListInit(&pThis->lstStreams);
 #ifdef VBOX_WITH_AUDIO_CALLBACKS
     RTListInit(&pThis->In.lstCB);
@@ -3733 +3402 @@
 
     PPDMAUDIOSTREAM pStream, pStreamNext;
-    RTListForEachSafe(&pThis->lstHstStreams, pStream, pStreamNext, PDMAUDIOSTREAM, Node)
+    RTListForEachSafe(&pThis->lstStreams, pStream, pStreamNext, PDMAUDIOSTREAM, Node)
     {
         rc2 = drvAudioStreamUninitInternal(pThis, pStream);
@@ -3746 +3415 @@
 
     /* Sanity. */
-    Assert(RTListIsEmpty(&pThis->lstHstStreams));
-
-    RTListForEachSafe(&pThis->lstGstStreams, pStream, pStreamNext, PDMAUDIOSTREAM, Node)
-    {
-        rc2 = drvAudioStreamUninitInternal(pThis, pStream);
-        if (RT_SUCCESS(rc2))
-        {
-            RTListNodeRemove(&pStream->Node);
-
-            RTMemFree(pStream);
-            pStream = NULL;
-        }
-    }
-
-    /* Sanity. */
-    Assert(RTListIsEmpty(&pThis->lstGstStreams));
+    Assert(RTListIsEmpty(&pThis->lstStreams));
 
 #ifdef VBOX_WITH_AUDIO_CALLBACKS

trunk/src/VBox/Devices/Audio/DrvAudio.h

@@ -123 +123 @@
     /** Pointer to CFGM configuration node of this driver. */
     PCFGMNODE               pCFGMNode;
-    /** List of host input/output audio streams. */
-    RTLISTANCHOR            lstHstStreams;
-    /** List of guest input/output audio streams. */
-    RTLISTANCHOR            lstGstStreams;
+    /** List of audio streams. */
+    RTLISTANCHOR            lstStreams;
 #ifdef VBOX_WITH_AUDIO_ENUM
     /** Flag indicating to perform an (re-)enumeration of the host audio devices. */