1 /*
2 * Interface to libgsm for GSM 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 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 "config.h"
31 #if HAVE_GSM_H
32 #include <gsm.h>
33 #else
34 #include <gsm/gsm.h>
35 #endif
36
37 #include "libavutil/channel_layout.h"
38 #include "libavutil/common.h"
39
40 #include "avcodec.h"
41 #include "internal.h"
42 #include "gsm.h"
43
44 typedef struct LibGSMDecodeContext {
45 struct gsm_state *state;
46 } LibGSMDecodeContext;
47
libgsm_decode_init(AVCodecContext * avctx)48 static av_cold int libgsm_decode_init(AVCodecContext *avctx) {
49 LibGSMDecodeContext *s = avctx->priv_data;
50
51 avctx->channels = 1;
52 avctx->channel_layout = AV_CH_LAYOUT_MONO;
53 if (!avctx->sample_rate)
54 avctx->sample_rate = 8000;
55 avctx->sample_fmt = AV_SAMPLE_FMT_S16;
56
57 s->state = gsm_create();
58
59 switch(avctx->codec_id) {
60 case AV_CODEC_ID_GSM:
61 avctx->frame_size = GSM_FRAME_SIZE;
62 avctx->block_align = GSM_BLOCK_SIZE;
63 break;
64 case AV_CODEC_ID_GSM_MS: {
65 int one = 1;
66 gsm_option(s->state, GSM_OPT_WAV49, &one);
67 avctx->frame_size = 2 * GSM_FRAME_SIZE;
68 avctx->block_align = GSM_MS_BLOCK_SIZE;
69 }
70 }
71
72 return 0;
73 }
74
libgsm_decode_close(AVCodecContext * avctx)75 static av_cold int libgsm_decode_close(AVCodecContext *avctx) {
76 LibGSMDecodeContext *s = avctx->priv_data;
77
78 gsm_destroy(s->state);
79 s->state = NULL;
80 return 0;
81 }
82
libgsm_decode_frame(AVCodecContext * avctx,void * data,int * got_frame_ptr,AVPacket * avpkt)83 static int libgsm_decode_frame(AVCodecContext *avctx, void *data,
84 int *got_frame_ptr, AVPacket *avpkt)
85 {
86 int i, ret;
87 LibGSMDecodeContext *s = avctx->priv_data;
88 AVFrame *frame = data;
89 uint8_t *buf = avpkt->data;
90 int buf_size = avpkt->size;
91 int16_t *samples;
92
93 if (buf_size < avctx->block_align) {
94 av_log(avctx, AV_LOG_ERROR, "Packet is too small\n");
95 return AVERROR_INVALIDDATA;
96 }
97
98 /* get output buffer */
99 frame->nb_samples = avctx->frame_size;
100 if ((ret = ff_get_buffer(avctx, frame, 0)) < 0)
101 return ret;
102 samples = (int16_t *)frame->data[0];
103
104 for (i = 0; i < avctx->frame_size / GSM_FRAME_SIZE; i++) {
105 if ((ret = gsm_decode(s->state, buf, samples)) < 0)
106 return -1;
107 buf += GSM_BLOCK_SIZE;
108 samples += GSM_FRAME_SIZE;
109 }
110
111 *got_frame_ptr = 1;
112
113 return avctx->block_align;
114 }
115
libgsm_flush(AVCodecContext * avctx)116 static void libgsm_flush(AVCodecContext *avctx) {
117 LibGSMDecodeContext *s = avctx->priv_data;
118 int one = 1;
119
120 gsm_destroy(s->state);
121 s->state = gsm_create();
122 if (avctx->codec_id == AV_CODEC_ID_GSM_MS)
123 gsm_option(s->state, GSM_OPT_WAV49, &one);
124 }
125
126 #if CONFIG_LIBGSM_DECODER
127 AVCodec ff_libgsm_decoder = {
128 .name = "libgsm",
129 .long_name = NULL_IF_CONFIG_SMALL("libgsm GSM"),
130 .type = AVMEDIA_TYPE_AUDIO,
131 .id = AV_CODEC_ID_GSM,
132 .priv_data_size = sizeof(LibGSMDecodeContext),
133 .init = libgsm_decode_init,
134 .close = libgsm_decode_close,
135 .decode = libgsm_decode_frame,
136 .flush = libgsm_flush,
137 .capabilities = AV_CODEC_CAP_DR1 | AV_CODEC_CAP_CHANNEL_CONF,
138 .wrapper_name = "libgsm",
139 };
140 #endif
141 #if CONFIG_LIBGSM_MS_DECODER
142 AVCodec ff_libgsm_ms_decoder = {
143 .name = "libgsm_ms",
144 .long_name = NULL_IF_CONFIG_SMALL("libgsm GSM Microsoft variant"),
145 .type = AVMEDIA_TYPE_AUDIO,
146 .id = AV_CODEC_ID_GSM_MS,
147 .priv_data_size = sizeof(LibGSMDecodeContext),
148 .init = libgsm_decode_init,
149 .close = libgsm_decode_close,
150 .decode = libgsm_decode_frame,
151 .flush = libgsm_flush,
152 .capabilities = AV_CODEC_CAP_DR1 | AV_CODEC_CAP_CHANNEL_CONF,
153 .wrapper_name = "libgsm",
154 };
155 #endif
156