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 #include "config_components.h"
32 #if HAVE_GSM_H
33 #include <gsm.h>
34 #else
35 #include <gsm/gsm.h>
36 #endif
37
38 #include "libavutil/channel_layout.h"
39 #include "libavutil/common.h"
40
41 #include "avcodec.h"
42 #include "codec_internal.h"
43 #include "internal.h"
44 #include "gsm.h"
45
46 typedef struct LibGSMDecodeContext {
47 struct gsm_state *state;
48 } LibGSMDecodeContext;
49
libgsm_decode_init(AVCodecContext *avctx)50 static av_cold int libgsm_decode_init(AVCodecContext *avctx) {
51 LibGSMDecodeContext *s = avctx->priv_data;
52
53 av_channel_layout_uninit(&avctx->ch_layout);
54 avctx->ch_layout = (AVChannelLayout)AV_CHANNEL_LAYOUT_MONO;
55 if (!avctx->sample_rate)
56 avctx->sample_rate = 8000;
57 avctx->sample_fmt = AV_SAMPLE_FMT_S16;
58
59 s->state = gsm_create();
60
61 switch(avctx->codec_id) {
62 case AV_CODEC_ID_GSM:
63 avctx->frame_size = GSM_FRAME_SIZE;
64 avctx->block_align = GSM_BLOCK_SIZE;
65 break;
66 case AV_CODEC_ID_GSM_MS: {
67 int one = 1;
68 gsm_option(s->state, GSM_OPT_WAV49, &one);
69 avctx->frame_size = 2 * GSM_FRAME_SIZE;
70 avctx->block_align = GSM_MS_BLOCK_SIZE;
71 }
72 }
73
74 return 0;
75 }
76
libgsm_decode_close(AVCodecContext *avctx)77 static av_cold int libgsm_decode_close(AVCodecContext *avctx) {
78 LibGSMDecodeContext *s = avctx->priv_data;
79
80 gsm_destroy(s->state);
81 s->state = NULL;
82 return 0;
83 }
84
libgsm_decode_frame(AVCodecContext *avctx, AVFrame *frame, int *got_frame_ptr, AVPacket *avpkt)85 static int libgsm_decode_frame(AVCodecContext *avctx, AVFrame *frame,
86 int *got_frame_ptr, AVPacket *avpkt)
87 {
88 int i, ret;
89 LibGSMDecodeContext *s = avctx->priv_data;
90 uint8_t *buf = avpkt->data;
91 int buf_size = avpkt->size;
92 int16_t *samples;
93
94 if (buf_size < avctx->block_align) {
95 av_log(avctx, AV_LOG_ERROR, "Packet is too small\n");
96 return AVERROR_INVALIDDATA;
97 }
98
99 /* get output buffer */
100 frame->nb_samples = avctx->frame_size;
101 if ((ret = ff_get_buffer(avctx, frame, 0)) < 0)
102 return ret;
103 samples = (int16_t *)frame->data[0];
104
105 for (i = 0; i < avctx->frame_size / GSM_FRAME_SIZE; i++) {
106 if ((ret = gsm_decode(s->state, buf, samples)) < 0)
107 return -1;
108 buf += GSM_BLOCK_SIZE;
109 samples += GSM_FRAME_SIZE;
110 }
111
112 *got_frame_ptr = 1;
113
114 return avctx->block_align;
115 }
116
libgsm_flush(AVCodecContext *avctx)117 static void libgsm_flush(AVCodecContext *avctx) {
118 LibGSMDecodeContext *s = avctx->priv_data;
119 int one = 1;
120
121 gsm_destroy(s->state);
122 s->state = gsm_create();
123 if (avctx->codec_id == AV_CODEC_ID_GSM_MS)
124 gsm_option(s->state, GSM_OPT_WAV49, &one);
125 }
126
127 #if CONFIG_LIBGSM_DECODER
128 const FFCodec ff_libgsm_decoder = {
129 .p.name = "libgsm",
130 .p.long_name = NULL_IF_CONFIG_SMALL("libgsm GSM"),
131 .p.type = AVMEDIA_TYPE_AUDIO,
132 .p.id = AV_CODEC_ID_GSM,
133 .p.capabilities = AV_CODEC_CAP_DR1 | AV_CODEC_CAP_CHANNEL_CONF,
134 .p.wrapper_name = "libgsm",
135 .priv_data_size = sizeof(LibGSMDecodeContext),
136 .init = libgsm_decode_init,
137 .close = libgsm_decode_close,
138 FF_CODEC_DECODE_CB(libgsm_decode_frame),
139 .flush = libgsm_flush,
140 };
141 #endif
142 #if CONFIG_LIBGSM_MS_DECODER
143 const FFCodec ff_libgsm_ms_decoder = {
144 .p.name = "libgsm_ms",
145 .p.long_name = NULL_IF_CONFIG_SMALL("libgsm GSM Microsoft variant"),
146 .p.type = AVMEDIA_TYPE_AUDIO,
147 .p.id = AV_CODEC_ID_GSM_MS,
148 .p.capabilities = AV_CODEC_CAP_DR1 | AV_CODEC_CAP_CHANNEL_CONF,
149 .p.wrapper_name = "libgsm",
150 .priv_data_size = sizeof(LibGSMDecodeContext),
151 .init = libgsm_decode_init,
152 .close = libgsm_decode_close,
153 FF_CODEC_DECODE_CB(libgsm_decode_frame),
154 .flush = libgsm_flush,
155 };
156 #endif
157