| 1 | /**
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| 2 | * @file mpegaudio.h
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| 3 | * mpeg audio declarations for both encoder and decoder.
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| 4 | */
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| 5 |
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| 6 | /* max frame size, in samples */
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| 7 | #define MPA_FRAME_SIZE 1152
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| 8 |
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| 9 | /* max compressed frame size */
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| 10 | #define MPA_MAX_CODED_FRAME_SIZE 1792
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| 11 |
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| 12 | #define MPA_MAX_CHANNELS 2
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| 13 |
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| 14 | #define SBLIMIT 32 /* number of subbands */
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| 15 |
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| 16 | #define MPA_STEREO 0
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| 17 | #define MPA_JSTEREO 1
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| 18 | #define MPA_DUAL 2
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| 19 | #define MPA_MONO 3
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| 20 |
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| 21 | /* header + layer + bitrate + freq + lsf/mpeg25 */
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| 22 | #define SAME_HEADER_MASK \
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| 23 | (0xffe00000 | (3 << 17) | (0xf << 12) | (3 << 10) | (3 << 19))
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| 24 |
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| 25 | /* define USE_HIGHPRECISION to have a bit exact (but slower) mpeg
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| 26 | audio decoder */
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| 27 |
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| 28 | #ifdef USE_HIGHPRECISION
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| 29 | #define FRAC_BITS 23 /* fractional bits for sb_samples and dct */
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| 30 | #define WFRAC_BITS 16 /* fractional bits for window */
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| 31 | #else
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| 32 | #define FRAC_BITS 15 /* fractional bits for sb_samples and dct */
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| 33 | #define WFRAC_BITS 14 /* fractional bits for window */
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| 34 | #endif
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| 35 |
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| 36 | #if defined(USE_HIGHPRECISION) && defined(CONFIG_AUDIO_NONSHORT)
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| 37 | typedef int32_t OUT_INT;
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| 38 | #define OUT_MAX INT32_MAX
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| 39 | #define OUT_MIN INT32_MIN
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| 40 | #define OUT_SHIFT (WFRAC_BITS + FRAC_BITS - 31)
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| 41 | #else
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| 42 | typedef int16_t OUT_INT;
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| 43 | #define OUT_MAX INT16_MAX
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| 44 | #define OUT_MIN INT16_MIN
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| 45 | #define OUT_SHIFT (WFRAC_BITS + FRAC_BITS - 15)
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| 46 | #endif
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| 47 |
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| 48 | #if FRAC_BITS <= 15
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| 49 | typedef int16_t MPA_INT;
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| 50 | #else
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| 51 | typedef int32_t MPA_INT;
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| 52 | #endif
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| 53 |
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| 54 | int l2_select_table(int bitrate, int nb_channels, int freq, int lsf);
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| 55 | int mpa_decode_header(AVCodecContext *avctx, uint32_t head);
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| 56 | void ff_mpa_synth_init(MPA_INT *window);
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| 57 | void ff_mpa_synth_filter(MPA_INT *synth_buf_ptr, int *synth_buf_offset,
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| 58 | MPA_INT *window, int *dither_state,
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| 59 | OUT_INT *samples, int incr,
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| 60 | int32_t sb_samples[SBLIMIT]);
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| 61 |
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| 62 | extern const uint16_t mpa_bitrate_tab[2][3][15];
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| 63 | extern const uint16_t mpa_freq_tab[3];
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| 64 | extern const unsigned char *alloc_tables[5];
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| 65 | extern const double enwindow[512];
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| 66 | extern const int sblimit_table[5];
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| 67 | extern const int quant_steps[17];
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| 68 | extern const int quant_bits[17];
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| 69 | extern const int32_t mpa_enwindow[257];
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| 70 |
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| 71 | /* fast header check for resync */
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| 72 | static inline int ff_mpa_check_header(uint32_t header){
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| 73 | /* header */
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| 74 | if ((header & 0xffe00000) != 0xffe00000)
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| 75 | return -1;
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| 76 | /* layer check */
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| 77 | if ((header & (3<<17)) == 0)
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| 78 | return -1;
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| 79 | /* bit rate */
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| 80 | if ((header & (0xf<<12)) == 0xf<<12)
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| 81 | return -1;
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| 82 | /* frequency */
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| 83 | if ((header & (3<<10)) == 3<<10)
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| 84 | return -1;
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| 85 | return 0;
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| 86 | }
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