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
  52         avctx->sample_fmt = SAMPLE_FMT_S16;
  53     }else{
  54         if (avctx->sample_rate != 8000) {
  55             av_log(avctx, AV_LOG_ERROR, "Sample rate 8000Hz required for GSM, got %dHz\n",
  56                 avctx->sample_rate);
  57             if(avctx->strict_std_compliance > FF_COMPLIANCE_INOFFICIAL)
  58                 return -1;
  59         }
  60         if (avctx->bit_rate != 13000 /* Official */ &&
  61             avctx->bit_rate != 13200 /* Very common */ &&
  62             avctx->bit_rate != 0 /* Unknown; a.o. mov does not set bitrate when decoding */ ) {
  63             av_log(avctx, AV_LOG_ERROR, "Bitrate 13000bps required for GSM, got %dbps\n",
  64                 avctx->bit_rate);
  65             if(avctx->strict_std_compliance > FF_COMPLIANCE_INOFFICIAL)
  66                 return -1;
  67         }
  68     }
  69
  70     avctx->priv_data = gsm_create();
  71
  72     switch(avctx->codec_id) {
  73     case CODEC_ID_GSM:
  74         avctx->frame_size = GSM_FRAME_SIZE;
  75         avctx->block_align = GSM_BLOCK_SIZE;
  76         break;
  77     case CODEC_ID_GSM_MS: {
  78         int one = 1;
  79         gsm_option(avctx->priv_data, GSM_OPT_WAV49, &one);
  80         avctx->frame_size = 2*GSM_FRAME_SIZE;
  81         avctx->block_align = GSM_MS_BLOCK_SIZE;
  82         }
  83     }
  84
  85     avctx->coded_frame= avcodec_alloc_frame();
  86     avctx->coded_frame->key_frame= 1;
  87
  88     return 0;
  89 }
  90
  91 static av_cold int libgsm_close(AVCodecContext *avctx) {
  92     gsm_destroy(avctx->priv_data);
  93     avctx->priv_data = NULL;
  94     return 0;
  95 }
  96
  97 static int libgsm_encode_frame(AVCodecContext *avctx,
  98                                unsigned char *frame, int buf_size, void *data) {
  99     // we need a full block
 100     if(buf_size < avctx->block_align) return 0;
 101
 102     switch(avctx->codec_id) {
 103     case CODEC_ID_GSM:
 104         gsm_encode(avctx->priv_data,data,frame);
 105         break;
 106     case CODEC_ID_GSM_MS:
 107         gsm_encode(avctx->priv_data,data,frame);
 108         gsm_encode(avctx->priv_data,((short*)data)+GSM_FRAME_SIZE,frame+32);
 109     }
 110     return avctx->block_align;
 111 }
 112
 113
 114 AVCodec libgsm_encoder = {
 115     "libgsm",
 116     CODEC_TYPE_AUDIO,
 117     CODEC_ID_GSM,
 118     0,
 119     libgsm_init,
 120     libgsm_encode_frame,
 121     libgsm_close,
 122     .sample_fmts = (enum SampleFormat[]){SAMPLE_FMT_S16,SAMPLE_FMT_NONE},
 123     .long_name = NULL_IF_CONFIG_SMALL("libgsm GSM"),
 124 };
 125
 126 AVCodec libgsm_ms_encoder = {
 127     "libgsm_ms",
 128     CODEC_TYPE_AUDIO,
 129     CODEC_ID_GSM_MS,
 130     0,
 131     libgsm_init,
 132     libgsm_encode_frame,
 133     libgsm_close,
 134     .sample_fmts = (enum SampleFormat[]){SAMPLE_FMT_S16,SAMPLE_FMT_NONE},
 135     .long_name = NULL_IF_CONFIG_SMALL("libgsm GSM Microsoft variant"),
 136 };
 137
 138 static int libgsm_decode_frame(AVCodecContext *avctx,
 139                                void *data, int *data_size,
 140                                uint8_t *buf, int buf_size) {
 141     *data_size = 0; /* In case of error */
 142     if(buf_size < avctx->block_align) return -1;
 143     switch(avctx->codec_id) {
 144     case CODEC_ID_GSM:
 145         if(gsm_decode(avctx->priv_data,buf,data)) return -1;
 146         *data_size = GSM_FRAME_SIZE*sizeof(int16_t);
 147         break;
 148     case CODEC_ID_GSM_MS:
 149         if(gsm_decode(avctx->priv_data,buf,data) ||
 150            gsm_decode(avctx->priv_data,buf+33,((int16_t*)data)+GSM_FRAME_SIZE)) return -1;
 151         *data_size = GSM_FRAME_SIZE*sizeof(int16_t)*2;
 152     }
 153     return avctx->block_align;
 154 }
 155
 156 AVCodec libgsm_decoder = {
 157     "libgsm",
 158     CODEC_TYPE_AUDIO,
 159     CODEC_ID_GSM,
 160     0,
 161     libgsm_init,
 162     NULL,
 163     libgsm_close,
 164     libgsm_decode_frame,
 165     .long_name = NULL_IF_CONFIG_SMALL("libgsm GSM"),
 166 };
 167
 168 AVCodec libgsm_ms_decoder = {
 169     "libgsm_ms",
 170     CODEC_TYPE_AUDIO,
 171     CODEC_ID_GSM_MS,
 172     0,
 173     libgsm_init,
 174     NULL,
 175     libgsm_close,
 176     libgsm_decode_frame,
 177     .long_name = NULL_IF_CONFIG_SMALL("libgsm GSM Microsoft variant"),
 178 };