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 miss 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 = {