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>
6 * This file is part of FFmpeg.
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.
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.
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
25 * Interface to libgsm for gsm encoding/decoding
28 // The idiosyncrasies of GSM-in-WAV are explained at http://kbs.cs.tu-berlin.de/~jutta/toast.html
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
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",
44 if (avctx->sample_rate != 8000) {
45 av_log(avctx, AV_LOG_ERROR, "Sample rate 8000Hz required for GSM, got %dHz\n",
49 if (avctx->bit_rate != 13000 /* Official */ &&
50 avctx->bit_rate != 13200 /* Very common */ &&
51 avctx->bit_rate != 0 /* Unknown; a.o. mov does not set bitrate when decoding */ ) {
52 av_log(avctx, AV_LOG_ERROR, "Bitrate 13000bps required for GSM, got %dbps\n",
57 avctx->priv_data = gsm_create();
59 switch(avctx->codec_id) {
61 avctx->frame_size = GSM_FRAME_SIZE;
62 avctx->block_align = GSM_BLOCK_SIZE;
64 case CODEC_ID_GSM_MS: {
66 gsm_option(avctx->priv_data, GSM_OPT_WAV49, &one);
67 avctx->frame_size = 2*GSM_FRAME_SIZE;
68 avctx->block_align = GSM_MS_BLOCK_SIZE;
72 avctx->coded_frame= avcodec_alloc_frame();
73 avctx->coded_frame->key_frame= 1;
78 static av_cold int libgsm_close(AVCodecContext *avctx) {
79 gsm_destroy(avctx->priv_data);
80 avctx->priv_data = NULL;
84 static int libgsm_encode_frame(AVCodecContext *avctx,
85 unsigned char *frame, int buf_size, void *data) {
86 // we need a full block
87 if(buf_size < avctx->block_align) return 0;
89 switch(avctx->codec_id) {
91 gsm_encode(avctx->priv_data,data,frame);
94 gsm_encode(avctx->priv_data,data,frame);
95 gsm_encode(avctx->priv_data,((short*)data)+GSM_FRAME_SIZE,frame+32);
97 return avctx->block_align;
101 AVCodec libgsm_encoder = {
111 AVCodec libgsm_ms_encoder = {
121 static int libgsm_decode_frame(AVCodecContext *avctx,
122 void *data, int *data_size,
123 uint8_t *buf, int buf_size) {
124 *data_size = 0; /* In case of error */
125 if(buf_size < avctx->block_align) return -1;
126 switch(avctx->codec_id) {
128 if(gsm_decode(avctx->priv_data,buf,data)) return -1;
129 *data_size = GSM_FRAME_SIZE*sizeof(int16_t);
131 case CODEC_ID_GSM_MS:
132 if(gsm_decode(avctx->priv_data,buf,data) ||
133 gsm_decode(avctx->priv_data,buf+33,((int16_t*)data)+GSM_FRAME_SIZE)) return -1;
134 *data_size = GSM_FRAME_SIZE*sizeof(int16_t)*2;
136 return avctx->block_align;
139 AVCodec libgsm_decoder = {
150 AVCodec libgsm_ms_decoder = {