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 int libgsm_init(AVCodecContext *avctx) {
39 if (avctx->channels > 1 || avctx->sample_rate != 8000 || avctx->bit_rate != 13000)
42 avctx->priv_data = gsm_create();
44 switch(avctx->codec_id) {
46 avctx->frame_size = GSM_FRAME_SIZE;
47 avctx->block_align = GSM_BLOCK_SIZE;
49 case CODEC_ID_GSM_MS: {
51 gsm_option(avctx->priv_data, GSM_OPT_WAV49, &one);
52 avctx->frame_size = 2*GSM_FRAME_SIZE;
53 avctx->block_align = GSM_MS_BLOCK_SIZE;
57 avctx->coded_frame= avcodec_alloc_frame();
58 avctx->coded_frame->key_frame= 1;
63 static int libgsm_close(AVCodecContext *avctx) {
64 gsm_destroy(avctx->priv_data);
65 avctx->priv_data = NULL;
69 static int libgsm_encode_frame(AVCodecContext *avctx,
70 unsigned char *frame, int buf_size, void *data) {
71 // we need a full block
72 if(buf_size < avctx->block_align) return 0;
74 switch(avctx->codec_id) {
76 gsm_encode(avctx->priv_data,data,frame);
79 gsm_encode(avctx->priv_data,data,frame);
80 gsm_encode(avctx->priv_data,((short*)data)+GSM_FRAME_SIZE,frame+32);
82 return avctx->block_align;
86 AVCodec libgsm_encoder = {
96 AVCodec libgsm_ms_encoder = {
106 static int libgsm_decode_frame(AVCodecContext *avctx,
107 void *data, int *data_size,
108 uint8_t *buf, int buf_size) {
110 if(buf_size < avctx->block_align) return 0;
112 switch(avctx->codec_id) {
114 if(gsm_decode(avctx->priv_data,buf,data)) return -1;
115 *data_size = GSM_FRAME_SIZE*sizeof(int16_t);
117 case CODEC_ID_GSM_MS:
118 if(gsm_decode(avctx->priv_data,buf,data) ||
119 gsm_decode(avctx->priv_data,buf+33,((int16_t*)data)+GSM_FRAME_SIZE)) return -1;
120 *data_size = GSM_FRAME_SIZE*sizeof(int16_t)*2;
122 return avctx->block_align;
125 AVCodec libgsm_decoder = {
136 AVCodec libgsm_ms_decoder = {