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  1. /*
  2.  * Interface to libgsm for GSM decoding
  3.  * Copyright (c) 2005 Alban Bedel <albeu@free.fr>
  4.  * Copyright (c) 2006, 2007 Michel Bardiaux <mbardiaux@mediaxim.be>
  5.  *
  6.  * This file is part of FFmpeg.
  7.  *
  8.  * FFmpeg is free software; you can redistribute it and/or
  9.  * modify it under the terms of the GNU Lesser General Public
  10.  * License as published by the Free Software Foundation; either
  11.  * version 2.1 of the License, or (at your option) any later version.
  12.  *
  13.  * FFmpeg is distributed in the hope that it will be useful,
  14.  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  15.  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  16.  * Lesser General Public License for more details.
  17.  *
  18.  * You should have received a copy of the GNU Lesser General Public
  19.  * License along with FFmpeg; if not, write to the Free Software
  20.  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
  21.  */
  22.  
  23. /**
  24.  * @file
  25.  * Interface to libgsm for GSM decoding
  26.  */
  27.  
  28. // The idiosyncrasies of GSM-in-WAV are explained at http://kbs.cs.tu-berlin.de/~jutta/toast.html
  29.  
  30. #include "config.h"
  31. #if HAVE_GSM_H
  32. #include <gsm.h>
  33. #else
  34. #include <gsm/gsm.h>
  35. #endif
  36.  
  37. #include "libavutil/channel_layout.h"
  38. #include "libavutil/common.h"
  39.  
  40. #include "avcodec.h"
  41. #include "internal.h"
  42. #include "gsm.h"
  43.  
  44. typedef struct LibGSMDecodeContext {
  45.     struct gsm_state *state;
  46. } LibGSMDecodeContext;
  47.  
  48. static av_cold int libgsm_decode_init(AVCodecContext *avctx) {
  49.     LibGSMDecodeContext *s = avctx->priv_data;
  50.  
  51.     avctx->channels       = 1;
  52.     avctx->channel_layout = AV_CH_LAYOUT_MONO;
  53.     if (!avctx->sample_rate)
  54.         avctx->sample_rate = 8000;
  55.     avctx->sample_fmt     = AV_SAMPLE_FMT_S16;
  56.  
  57.     s->state = gsm_create();
  58.  
  59.     switch(avctx->codec_id) {
  60.     case AV_CODEC_ID_GSM:
  61.         avctx->frame_size  = GSM_FRAME_SIZE;
  62.         avctx->block_align = GSM_BLOCK_SIZE;
  63.         break;
  64.     case AV_CODEC_ID_GSM_MS: {
  65.         int one = 1;
  66.         gsm_option(s->state, GSM_OPT_WAV49, &one);
  67.         avctx->frame_size  = 2 * GSM_FRAME_SIZE;
  68.         avctx->block_align = GSM_MS_BLOCK_SIZE;
  69.         }
  70.     }
  71.  
  72.     return 0;
  73. }
  74.  
  75. static av_cold int libgsm_decode_close(AVCodecContext *avctx) {
  76.     LibGSMDecodeContext *s = avctx->priv_data;
  77.  
  78.     gsm_destroy(s->state);
  79.     s->state = NULL;
  80.     return 0;
  81. }
  82.  
  83. static int libgsm_decode_frame(AVCodecContext *avctx, void *data,
  84.                                int *got_frame_ptr, AVPacket *avpkt)
  85. {
  86.     int i, ret;
  87.     LibGSMDecodeContext *s = avctx->priv_data;
  88.     AVFrame *frame         = data;
  89.     uint8_t *buf = avpkt->data;
  90.     int buf_size = avpkt->size;
  91.     int16_t *samples;
  92.  
  93.     if (buf_size < avctx->block_align) {
  94.         av_log(avctx, AV_LOG_ERROR, "Packet is too small\n");
  95.         return AVERROR_INVALIDDATA;
  96.     }
  97.  
  98.     /* get output buffer */
  99.     frame->nb_samples = avctx->frame_size;
  100.     if ((ret = ff_get_buffer(avctx, frame, 0)) < 0)
  101.         return ret;
  102.     samples = (int16_t *)frame->data[0];
  103.  
  104.     for (i = 0; i < avctx->frame_size / GSM_FRAME_SIZE; i++) {
  105.         if ((ret = gsm_decode(s->state, buf, samples)) < 0)
  106.             return -1;
  107.         buf     += GSM_BLOCK_SIZE;
  108.         samples += GSM_FRAME_SIZE;
  109.     }
  110.  
  111.     *got_frame_ptr = 1;
  112.  
  113.     return avctx->block_align;
  114. }
  115.  
  116. static void libgsm_flush(AVCodecContext *avctx) {
  117.     LibGSMDecodeContext *s = avctx->priv_data;
  118.     int one = 1;
  119.  
  120.     gsm_destroy(s->state);
  121.     s->state = gsm_create();
  122.     if (avctx->codec_id == AV_CODEC_ID_GSM_MS)
  123.         gsm_option(s->state, GSM_OPT_WAV49, &one);
  124. }
  125.  
  126. #if CONFIG_LIBGSM_DECODER
  127. AVCodec ff_libgsm_decoder = {
  128.     .name           = "libgsm",
  129.     .long_name      = NULL_IF_CONFIG_SMALL("libgsm GSM"),
  130.     .type           = AVMEDIA_TYPE_AUDIO,
  131.     .id             = AV_CODEC_ID_GSM,
  132.     .priv_data_size = sizeof(LibGSMDecodeContext),
  133.     .init           = libgsm_decode_init,
  134.     .close          = libgsm_decode_close,
  135.     .decode         = libgsm_decode_frame,
  136.     .flush          = libgsm_flush,
  137.     .capabilities   = AV_CODEC_CAP_DR1,
  138. };
  139. #endif
  140. #if CONFIG_LIBGSM_MS_DECODER
  141. AVCodec ff_libgsm_ms_decoder = {
  142.     .name           = "libgsm_ms",
  143.     .long_name      = NULL_IF_CONFIG_SMALL("libgsm GSM Microsoft variant"),
  144.     .type           = AVMEDIA_TYPE_AUDIO,
  145.     .id             = AV_CODEC_ID_GSM_MS,
  146.     .priv_data_size = sizeof(LibGSMDecodeContext),
  147.     .init           = libgsm_decode_init,
  148.     .close          = libgsm_decode_close,
  149.     .decode         = libgsm_decode_frame,
  150.     .flush          = libgsm_flush,
  151.     .capabilities   = AV_CODEC_CAP_DR1,
  152. };
  153. #endif
  154.