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
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/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
38static 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
91static av_cold int libgsm_close(AVCodecContext *avctx) {
92    av_freep(&avctx->coded_frame);
93    gsm_destroy(avctx->priv_data);
94    avctx->priv_data = NULL;
95    return 0;
96}
97
98static int libgsm_encode_frame(AVCodecContext *avctx,
99                               unsigned char *frame, int buf_size, void *data) {
100    // we need a full block
101    if(buf_size < avctx->block_align) return 0;
102
103    switch(avctx->codec_id) {
104    case CODEC_ID_GSM:
105        gsm_encode(avctx->priv_data,data,frame);
106        break;
107    case CODEC_ID_GSM_MS:
108        gsm_encode(avctx->priv_data,data,frame);
109        gsm_encode(avctx->priv_data,((short*)data)+GSM_FRAME_SIZE,frame+32);
110    }
111    return avctx->block_align;
112}
113
114
115AVCodec libgsm_encoder = {
116    "libgsm",
117    AVMEDIA_TYPE_AUDIO,
118    CODEC_ID_GSM,
119    0,
120    libgsm_init,
121    libgsm_encode_frame,
122    libgsm_close,
123    .sample_fmts = (const enum SampleFormat[]){SAMPLE_FMT_S16,SAMPLE_FMT_NONE},
124    .long_name = NULL_IF_CONFIG_SMALL("libgsm GSM"),
125};
126
127AVCodec libgsm_ms_encoder = {
128    "libgsm_ms",
129    AVMEDIA_TYPE_AUDIO,
130    CODEC_ID_GSM_MS,
131    0,
132    libgsm_init,
133    libgsm_encode_frame,
134    libgsm_close,
135    .sample_fmts = (const enum SampleFormat[]){SAMPLE_FMT_S16,SAMPLE_FMT_NONE},
136    .long_name = NULL_IF_CONFIG_SMALL("libgsm GSM Microsoft variant"),
137};
138
139static int libgsm_decode_frame(AVCodecContext *avctx,
140                               void *data, int *data_size,
141                               AVPacket *avpkt) {
142    const uint8_t *buf = avpkt->data;
143    int buf_size = avpkt->size;
144    *data_size = 0; /* In case of error */
145    if(buf_size < avctx->block_align) return -1;
146    switch(avctx->codec_id) {
147    case CODEC_ID_GSM:
148        if(gsm_decode(avctx->priv_data,buf,data)) return -1;
149        *data_size = GSM_FRAME_SIZE*sizeof(int16_t);
150        break;
151    case CODEC_ID_GSM_MS:
152        if(gsm_decode(avctx->priv_data,buf,data) ||
153           gsm_decode(avctx->priv_data,buf+33,((int16_t*)data)+GSM_FRAME_SIZE)) return -1;
154        *data_size = GSM_FRAME_SIZE*sizeof(int16_t)*2;
155    }
156    return avctx->block_align;
157}
158
159AVCodec libgsm_decoder = {
160    "libgsm",
161    AVMEDIA_TYPE_AUDIO,
162    CODEC_ID_GSM,
163    0,
164    libgsm_init,
165    NULL,
166    libgsm_close,
167    libgsm_decode_frame,
168    .long_name = NULL_IF_CONFIG_SMALL("libgsm GSM"),
169};
170
171AVCodec libgsm_ms_decoder = {
172    "libgsm_ms",
173    AVMEDIA_TYPE_AUDIO,
174    CODEC_ID_GSM_MS,
175    0,
176    libgsm_init,
177    NULL,
178    libgsm_close,
179    libgsm_decode_frame,
180    .long_name = NULL_IF_CONFIG_SMALL("libgsm GSM Microsoft variant"),
181};
182