| 1 | /*
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| 2 | * Interface to libgsm for gsm encoding/decoding
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| 3 | * Copyright (c) 2005 Alban Bedel <[email protected]>
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| 4 | *
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| 5 | * This library is free software; you can redistribute it and/or
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| 6 | * modify it under the terms of the GNU Lesser General Public
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| 7 | * License as published by the Free Software Foundation; either
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| 8 | * version 2 of the License, or (at your option) any later version.
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| 9 | *
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| 10 | * This library is distributed in the hope that it will be useful,
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| 11 | * but WITHOUT ANY WARRANTY; without even the implied warranty of
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| 12 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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| 13 | * Lesser General Public License for more details.
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| 14 | *
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| 15 | * You should have received a copy of the GNU Lesser General Public
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| 16 | * License along with this library; if not, write to the Free Software
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| 17 | * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
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| 18 | */
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| 19 |
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| 20 | /**
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| 21 | * @file libgsm.c
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| 22 | * Interface to libgsm for gsm encoding/decoding
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| 23 | */
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| 24 |
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| 25 | #include "avcodec.h"
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| 26 | #include <gsm.h>
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| 27 |
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| 28 | // gsm.h miss some essential constants
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| 29 | #define GSM_BLOCK_SIZE 33
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| 30 | #define GSM_FRAME_SIZE 160
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| 31 |
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| 32 | static int libgsm_init(AVCodecContext *avctx) {
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| 33 | if (avctx->channels > 1 || avctx->sample_rate != 8000)
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| 34 | return -1;
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| 35 |
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| 36 | avctx->frame_size = GSM_FRAME_SIZE;
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| 37 | avctx->block_align = GSM_BLOCK_SIZE;
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| 38 |
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| 39 | avctx->priv_data = gsm_create();
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| 40 |
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| 41 | avctx->coded_frame= avcodec_alloc_frame();
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| 42 | avctx->coded_frame->key_frame= 1;
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| 43 |
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| 44 | return 0;
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| 45 | }
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| 46 |
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| 47 | static int libgsm_close(AVCodecContext *avctx) {
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| 48 | gsm_destroy(avctx->priv_data);
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| 49 | avctx->priv_data = NULL;
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| 50 | return 0;
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| 51 | }
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| 52 |
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| 53 | static int libgsm_encode_frame(AVCodecContext *avctx,
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| 54 | unsigned char *frame, int buf_size, void *data) {
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| 55 | // we need a full block
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| 56 | if(buf_size < GSM_BLOCK_SIZE) return 0;
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| 57 |
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| 58 | gsm_encode(avctx->priv_data,data,frame);
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| 59 |
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| 60 | return GSM_BLOCK_SIZE;
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| 61 | }
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| 62 |
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| 63 |
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| 64 | AVCodec libgsm_encoder = {
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| 65 | "gsm",
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| 66 | CODEC_TYPE_AUDIO,
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| 67 | CODEC_ID_GSM,
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| 68 | 0,
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| 69 | libgsm_init,
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| 70 | libgsm_encode_frame,
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| 71 | libgsm_close,
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| 72 | };
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| 73 |
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| 74 | static int libgsm_decode_frame(AVCodecContext *avctx,
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| 75 | void *data, int *data_size,
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| 76 | uint8_t *buf, int buf_size) {
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| 77 |
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| 78 | if(buf_size < GSM_BLOCK_SIZE) return 0;
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| 79 |
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| 80 | if(gsm_decode(avctx->priv_data,buf,data)) return -1;
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| 81 |
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| 82 | *data_size = GSM_FRAME_SIZE*2;
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| 83 | return GSM_BLOCK_SIZE;
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| 84 | }
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| 85 |
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| 86 | AVCodec libgsm_decoder = {
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| 87 | "gsm",
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| 88 | CODEC_TYPE_AUDIO,
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| 89 | CODEC_ID_GSM,
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| 90 | 0,
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| 91 | libgsm_init,
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| 92 | NULL,
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| 93 | libgsm_close,
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| 94 | libgsm_decode_frame,
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| 95 | };
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