libavcodec/libgsm.c

   1 /*
   2  * Interface to libgsm for gsm encoding/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 libgsm.c
  25  * Interface to libgsm for gsm encoding/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 "avcodec.h"
  31 #include <gsm.h>
  32
  33 // gsm.h misses some essential constants
  34 #define GSM_BLOCK_SIZE 33
  35 #define GSM_MS_BLOCK_SIZE 65
  36 #define GSM_FRAME_SIZE 160
  37
  38 static av_cold int libgsm_init(AVCodecContext *avctx) {
  39     if (avctx->channels > 1) {
  40         av_log(avctx, AV_LOG_ERROR, "Mono required for GSM, got %d channels\n",
  41                avctx->channels);
  42         return -1;
  43     }
  44
  45     if(avctx->codec->decode){
  46         if(!avctx->channels)
  47             avctx->channels= 1;
  48
  49         if(!avctx->sample_rate)
  50             avctx->sample_rate= 8000;
  51     }else{
  52         if (avctx->sample_rate != 8000) {
  53             av_log(avctx, AV_LOG_ERROR, "Sample rate 8000Hz required for GSM, got %dHz\n",
  54                 avctx->sample_rate);
  55             if(avctx->strict_std_compliance > FF_COMPLIANCE_INOFFICIAL)
  56                 return -1;
  57         }
  58         if (avctx->bit_rate != 13000 /* Official */ &&
  59             avctx->bit_rate != 13200 /* Very common */ &&
  60             avctx->bit_rate != 0 /* Unknown; a.o. mov does not set bitrate when decoding */ ) {
  61             av_log(avctx, AV_LOG_ERROR, "Bitrate 13000bps required for GSM, got %dbps\n",
  62                 avctx->bit_rate);
  63             if(avctx->strict_std_compliance > FF_COMPLIANCE_INOFFICIAL)
  64                 return -1;
  65         }
  66     }
  67
  68     avctx->priv_data = gsm_create();
  69
  70     switch(avctx->codec_id) {
  71     case CODEC_ID_GSM:
  72         avctx->frame_size = GSM_FRAME_SIZE;
  73         avctx->block_align = GSM_BLOCK_SIZE;
  74         break;
  75     case CODEC_ID_GSM_MS: {
  76         int one = 1;
  77         gsm_option(avctx->priv_data, GSM_OPT_WAV49, &one);
  78         avctx->frame_size = 2*GSM_FRAME_SIZE;
  79         avctx->block_align = GSM_MS_BLOCK_SIZE;
  80         }
  81     }
  82
  83     avctx->coded_frame= avcodec_alloc_frame();
  84     avctx->coded_frame->key_frame= 1;
  85
  86     return 0;
  87 }
  88
  89 static av_cold int libgsm_close(AVCodecContext *avctx) {
  90     gsm_destroy(avctx->priv_data);
  91     avctx->priv_data = NULL;
  92     return 0;
  93 }
  94
  95 static int libgsm_encode_frame(AVCodecContext *avctx,
  96                                unsigned char *frame, int buf_size, void *data) {
  97     // we need a full block
  98     if(buf_size < avctx->block_align) return 0;
  99
 100     switch(avctx->codec_id) {
 101     case CODEC_ID_GSM:
 102         gsm_encode(avctx->priv_data,data,frame);
 103         break;
 104     case CODEC_ID_GSM_MS:
 105         gsm_encode(avctx->priv_data,data,frame);
 106         gsm_encode(avctx->priv_data,((short*)data)+GSM_FRAME_SIZE,frame+32);
 107     }
 108     return avctx->block_align;
 109 }
 110
 111
 112 AVCodec libgsm_encoder = {
 113     "libgsm",
 114     CODEC_TYPE_AUDIO,
 115     CODEC_ID_GSM,
 116     0,
 117     libgsm_init,
 118     libgsm_encode_frame,
 119     libgsm_close,
 120     .long_name = "libgsm GSM",
 121 };
 122
 123 AVCodec libgsm_ms_encoder = {
 124     "libgsm_ms",
 125     CODEC_TYPE_AUDIO,
 126     CODEC_ID_GSM_MS,
 127     0,
 128     libgsm_init,
 129     libgsm_encode_frame,
 130     libgsm_close,
 131     .long_name = "libgsm GSM Microsoft variant",
 132 };
 133
 134 static int libgsm_decode_frame(AVCodecContext *avctx,
 135                                void *data, int *data_size,
 136                                uint8_t *buf, int buf_size) {
 137     *data_size = 0; /* In case of error */
 138     if(buf_size < avctx->block_align) return -1;
 139     switch(avctx->codec_id) {
 140     case CODEC_ID_GSM:
 141         if(gsm_decode(avctx->priv_data,buf,data)) return -1;
 142         *data_size = GSM_FRAME_SIZE*sizeof(int16_t);
 143         break;
 144     case CODEC_ID_GSM_MS:
 145         if(gsm_decode(avctx->priv_data,buf,data) ||
 146            gsm_decode(avctx->priv_data,buf+33,((int16_t*)data)+GSM_FRAME_SIZE)) return -1;
 147         *data_size = GSM_FRAME_SIZE*sizeof(int16_t)*2;
 148     }
 149     return avctx->block_align;
 150 }
 151
 152 AVCodec libgsm_decoder = {
 153     "libgsm",
 154     CODEC_TYPE_AUDIO,
 155     CODEC_ID_GSM,
 156     0,
 157     libgsm_init,
 158     NULL,
 159     libgsm_close,
 160     libgsm_decode_frame,
 161     .long_name = "libgsm GSM",
 162 };
 163
 164 AVCodec libgsm_ms_decoder = {
 165     "libgsm_ms",
 166     CODEC_TYPE_AUDIO,
 167     CODEC_ID_GSM_MS,
 168     0,
 169     libgsm_init,
 170     NULL,
 171     libgsm_close,
 172     libgsm_decode_frame,
 173     .long_name = "libgsm GSM Microsoft variant",
 174 };