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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.     avctx->channels       = 1;
  38.     avctx->channel_layout = AV_CH_LAYOUT_MONO;
  39.     if (!avctx->sample_rate)
  40.         avctx->sample_rate = 8000;
  41.     avctx->sample_fmt     = AV_SAMPLE_FMT_S16;
  42.  
  43.     switch (avctx->codec_id) {
  44.     case AV_CODEC_ID_GSM:
  45.         avctx->frame_size  = GSM_FRAME_SIZE;
  46.         avctx->block_align = GSM_BLOCK_SIZE;
  47.         break;
  48.     case AV_CODEC_ID_GSM_MS:
  49.         avctx->frame_size  = 2 * GSM_FRAME_SIZE;
  50.         if (!avctx->block_align)
  51.             avctx->block_align = GSM_MS_BLOCK_SIZE;
  52.         else
  53.             if (avctx->block_align < MSN_MIN_BLOCK_SIZE ||
  54.                 avctx->block_align > GSM_MS_BLOCK_SIZE  ||
  55.                 (avctx->block_align - MSN_MIN_BLOCK_SIZE) % 3) {
  56.                 av_log(avctx, AV_LOG_ERROR, "Invalid block alignment %d\n",
  57.                        avctx->block_align);
  58.                 return AVERROR_INVALIDDATA;
  59.             }
  60.     }
  61.  
  62.     return 0;
  63. }
  64.  
  65. static int gsm_decode_frame(AVCodecContext *avctx, void *data,
  66.                             int *got_frame_ptr, AVPacket *avpkt)
  67. {
  68.     AVFrame *frame = data;
  69.     int res;
  70.     GetBitContext gb;
  71.     const uint8_t *buf = avpkt->data;
  72.     int buf_size = avpkt->size;
  73.     int16_t *samples;
  74.  
  75.     if (buf_size < avctx->block_align) {
  76.         av_log(avctx, AV_LOG_ERROR, "Packet is too small\n");
  77.         return AVERROR_INVALIDDATA;
  78.     }
  79.  
  80.     /* get output buffer */
  81.     frame->nb_samples = avctx->frame_size;
  82.     if ((res = ff_get_buffer(avctx, frame, 0)) < 0)
  83.         return res;
  84.     samples = (int16_t *)frame->data[0];
  85.  
  86.     switch (avctx->codec_id) {
  87.     case AV_CODEC_ID_GSM:
  88.         init_get_bits(&gb, buf, buf_size * 8);
  89.         if (get_bits(&gb, 4) != 0xd)
  90.             av_log(avctx, AV_LOG_WARNING, "Missing GSM magic!\n");
  91.         res = gsm_decode_block(avctx, samples, &gb, GSM_13000);
  92.         if (res < 0)
  93.             return res;
  94.         break;
  95.     case AV_CODEC_ID_GSM_MS:
  96.         res = ff_msgsm_decode_block(avctx, samples, buf,
  97.                                     (GSM_MS_BLOCK_SIZE - avctx->block_align) / 3);
  98.         if (res < 0)
  99.             return res;
  100.     }
  101.  
  102.     *got_frame_ptr = 1;
  103.  
  104.     return avctx->block_align;
  105. }
  106.  
  107. static void gsm_flush(AVCodecContext *avctx)
  108. {
  109.     GSMContext *s = avctx->priv_data;
  110.     memset(s, 0, sizeof(*s));
  111. }
  112.  
  113. #if CONFIG_GSM_DECODER
  114. AVCodec ff_gsm_decoder = {
  115.     .name           = "gsm",
  116.     .long_name      = NULL_IF_CONFIG_SMALL("GSM"),
  117.     .type           = AVMEDIA_TYPE_AUDIO,
  118.     .id             = AV_CODEC_ID_GSM,
  119.     .priv_data_size = sizeof(GSMContext),
  120.     .init           = gsm_init,
  121.     .decode         = gsm_decode_frame,
  122.     .flush          = gsm_flush,
  123.     .capabilities   = AV_CODEC_CAP_DR1,
  124. };
  125. #endif
  126. #if CONFIG_GSM_MS_DECODER
  127. AVCodec ff_gsm_ms_decoder = {
  128.     .name           = "gsm_ms",
  129.     .long_name      = NULL_IF_CONFIG_SMALL("GSM Microsoft variant"),
  130.     .type           = AVMEDIA_TYPE_AUDIO,
  131.     .id             = AV_CODEC_ID_GSM_MS,
  132.     .priv_data_size = sizeof(GSMContext),
  133.     .init           = gsm_init,
  134.     .decode         = gsm_decode_frame,
  135.     .flush          = gsm_flush,
  136.     .capabilities   = AV_CODEC_CAP_DR1,
  137. };
  138. #endif
  139.