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  1. /*
  2.  * gsm 06.10 decoder
  3.  * Copyright (c) 2010 Reimar Döffinger <Reimar.Doeffinger@gmx.de>
  4.  *
  5.  * This file is part of FFmpeg.
  6.  *
  7.  * FFmpeg is free software; you can redistribute it and/or
  8.  * modify it under the terms of the GNU Lesser General Public
  9.  * License as published by the Free Software Foundation; either
  10.  * version 2.1 of the License, or (at your option) any later version.
  11.  *
  12.  * FFmpeg is distributed in the hope that it will be useful,
  13.  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  14.  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  15.  * Lesser General Public License for more details.
  16.  *
  17.  * You should have received a copy of the GNU Lesser General Public
  18.  * License along with FFmpeg; if not, write to the Free Software
  19.  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
  20.  */
  21.  
  22. /**
  23.  * @file
  24.  * GSM decoder
  25.  */
  26.  
  27. #include "libavutil/channel_layout.h"
  28. #include "avcodec.h"
  29. #include "get_bits.h"
  30. #include "internal.h"
  31. #include "msgsmdec.h"
  32.  
  33. #include "gsmdec_template.c"
  34.  
  35. static av_cold int gsm_init(AVCodecContext *avctx)
  36. {
  37.     if (avctx->codec_tag == 0x0032 &&
  38.         avctx->bit_rate != 13000 &&
  39.         avctx->bit_rate != 17912 &&
  40.         avctx->bit_rate != 35824 &&
  41.         avctx->bit_rate != 71656) {
  42.         av_log(avctx, AV_LOG_ERROR, "Unsupported audio mode\n");
  43.         return AVERROR_PATCHWELCOME;
  44.     }
  45.     avctx->channels       = 1;
  46.     avctx->channel_layout = AV_CH_LAYOUT_MONO;
  47.     if (!avctx->sample_rate)
  48.         avctx->sample_rate = 8000;
  49.     avctx->sample_fmt     = AV_SAMPLE_FMT_S16;
  50.  
  51.     switch (avctx->codec_id) {
  52.     case AV_CODEC_ID_GSM:
  53.         avctx->frame_size  = GSM_FRAME_SIZE;
  54.         avctx->block_align = GSM_BLOCK_SIZE;
  55.         break;
  56.     case AV_CODEC_ID_GSM_MS:
  57.         avctx->frame_size  = 2 * GSM_FRAME_SIZE;
  58.         avctx->block_align = GSM_MS_BLOCK_SIZE;
  59.     }
  60.  
  61.     return 0;
  62. }
  63.  
  64. static int gsm_decode_frame(AVCodecContext *avctx, void *data,
  65.                             int *got_frame_ptr, AVPacket *avpkt)
  66. {
  67.     AVFrame *frame = data;
  68.     int res;
  69.     GetBitContext gb;
  70.     const uint8_t *buf = avpkt->data;
  71.     int buf_size = avpkt->size;
  72.     int16_t *samples;
  73.  
  74.     if (buf_size < avctx->block_align) {
  75.         av_log(avctx, AV_LOG_ERROR, "Packet is too small\n");
  76.         return AVERROR_INVALIDDATA;
  77.     }
  78.  
  79.     /* get output buffer */
  80.     frame->nb_samples = avctx->frame_size;
  81.     if ((res = ff_get_buffer(avctx, frame, 0)) < 0)
  82.         return res;
  83.     samples = (int16_t *)frame->data[0];
  84.  
  85.     switch (avctx->codec_id) {
  86.     case AV_CODEC_ID_GSM:
  87.         init_get_bits(&gb, buf, buf_size * 8);
  88.         if (get_bits(&gb, 4) != 0xd)
  89.             av_log(avctx, AV_LOG_WARNING, "Missing GSM magic!\n");
  90.         res = gsm_decode_block(avctx, samples, &gb);
  91.         if (res < 0)
  92.             return res;
  93.         break;
  94.     case AV_CODEC_ID_GSM_MS:
  95.         res = ff_msgsm_decode_block(avctx, samples, buf);
  96.         if (res < 0)
  97.             return res;
  98.     }
  99.  
  100.     *got_frame_ptr = 1;
  101.  
  102.     return avctx->block_align;
  103. }
  104.  
  105. static void gsm_flush(AVCodecContext *avctx)
  106. {
  107.     GSMContext *s = avctx->priv_data;
  108.     memset(s, 0, sizeof(*s));
  109. }
  110.  
  111. #if CONFIG_GSM_DECODER
  112. AVCodec ff_gsm_decoder = {
  113.     .name           = "gsm",
  114.     .long_name      = NULL_IF_CONFIG_SMALL("GSM"),
  115.     .type           = AVMEDIA_TYPE_AUDIO,
  116.     .id             = AV_CODEC_ID_GSM,
  117.     .priv_data_size = sizeof(GSMContext),
  118.     .init           = gsm_init,
  119.     .decode         = gsm_decode_frame,
  120.     .flush          = gsm_flush,
  121.     .capabilities   = CODEC_CAP_DR1,
  122. };
  123. #endif
  124. #if CONFIG_GSM_MS_DECODER
  125. AVCodec ff_gsm_ms_decoder = {
  126.     .name           = "gsm_ms",
  127.     .long_name      = NULL_IF_CONFIG_SMALL("GSM Microsoft variant"),
  128.     .type           = AVMEDIA_TYPE_AUDIO,
  129.     .id             = AV_CODEC_ID_GSM_MS,
  130.     .priv_data_size = sizeof(GSMContext),
  131.     .init           = gsm_init,
  132.     .decode         = gsm_decode_frame,
  133.     .flush          = gsm_flush,
  134.     .capabilities   = CODEC_CAP_DR1,
  135. };
  136. #endif
  137.