gsmdec.c
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1 /*
2  * gsm 06.10 decoder
3  * Copyright (c) 2010 Reimar Döffinger <Reimar.Doeffinger@gmx.de>
4  *
5  * This file is part of Libav.
6  *
7  * Libav is free software; you can redistribute it and/or
8  * modify it under the terms of the GNU Lesser General Public
9  * License as published by the Free Software Foundation; either
10  * version 2.1 of the License, or (at your option) any later version.
11  *
12  * Libav is distributed in the hope that it will be useful,
13  * but WITHOUT ANY WARRANTY; without even the implied warranty of
14  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
15  * Lesser General Public License for more details.
16  *
17  * You should have received a copy of the GNU Lesser General Public
18  * License along with Libav; if not, write to the Free Software
19  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
20  */
21 
28 #include "avcodec.h"
29 #include "get_bits.h"
30 #include "internal.h"
31 #include "msgsmdec.h"
32 
33 #include "gsmdec_template.c"
34 
35 static av_cold int gsm_init(AVCodecContext *avctx)
36 {
37  GSMContext *s = avctx->priv_data;
38 
39  avctx->channels = 1;
41  avctx->sample_rate = 8000;
43 
44  switch (avctx->codec_id) {
45  case AV_CODEC_ID_GSM:
46  avctx->frame_size = GSM_FRAME_SIZE;
47  avctx->block_align = GSM_BLOCK_SIZE;
48  break;
49  case AV_CODEC_ID_GSM_MS:
50  avctx->frame_size = 2 * GSM_FRAME_SIZE;
52  }
53 
55  avctx->coded_frame = &s->frame;
56 
57  return 0;
58 }
59 
60 static int gsm_decode_frame(AVCodecContext *avctx, void *data,
61  int *got_frame_ptr, AVPacket *avpkt)
62 {
63  GSMContext *s = avctx->priv_data;
64  int res;
65  GetBitContext gb;
66  const uint8_t *buf = avpkt->data;
67  int buf_size = avpkt->size;
68  int16_t *samples;
69 
70  if (buf_size < avctx->block_align) {
71  av_log(avctx, AV_LOG_ERROR, "Packet is too small\n");
72  return AVERROR_INVALIDDATA;
73  }
74 
75  /* get output buffer */
76  s->frame.nb_samples = avctx->frame_size;
77  if ((res = ff_get_buffer(avctx, &s->frame)) < 0) {
78  av_log(avctx, AV_LOG_ERROR, "get_buffer() failed\n");
79  return res;
80  }
81  samples = (int16_t *)s->frame.data[0];
82 
83  switch (avctx->codec_id) {
84  case AV_CODEC_ID_GSM:
85  init_get_bits(&gb, buf, buf_size * 8);
86  if (get_bits(&gb, 4) != 0xd)
87  av_log(avctx, AV_LOG_WARNING, "Missing GSM magic!\n");
88  res = gsm_decode_block(avctx, samples, &gb);
89  if (res < 0)
90  return res;
91  break;
92  case AV_CODEC_ID_GSM_MS:
93  res = ff_msgsm_decode_block(avctx, samples, buf);
94  if (res < 0)
95  return res;
96  }
97 
98  *got_frame_ptr = 1;
99  *(AVFrame *)data = s->frame;
100 
101  return avctx->block_align;
102 }
103 
104 static void gsm_flush(AVCodecContext *avctx)
105 {
106  GSMContext *s = avctx->priv_data;
107  memset(s, 0, sizeof(*s));
108 }
109 
111  .name = "gsm",
112  .type = AVMEDIA_TYPE_AUDIO,
113  .id = AV_CODEC_ID_GSM,
114  .priv_data_size = sizeof(GSMContext),
115  .init = gsm_init,
117  .flush = gsm_flush,
118  .capabilities = CODEC_CAP_DR1,
119  .long_name = NULL_IF_CONFIG_SMALL("GSM"),
120 };
121 
123  .name = "gsm_ms",
124  .type = AVMEDIA_TYPE_AUDIO,
125  .id = AV_CODEC_ID_GSM_MS,
126  .priv_data_size = sizeof(GSMContext),
127  .init = gsm_init,
129  .flush = gsm_flush,
130  .capabilities = CODEC_CAP_DR1,
131  .long_name = NULL_IF_CONFIG_SMALL("GSM Microsoft variant"),
132 };