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 
27 #include "avcodec.h"
28 #include "get_bits.h"
29 #include "msgsmdec.h"
30 
31 #include "gsmdec_template.c"
32 
33 static av_cold int gsm_init(AVCodecContext *avctx)
34 {
35  GSMContext *s = avctx->priv_data;
36 
37  avctx->channels = 1;
38  if (!avctx->sample_rate)
39  avctx->sample_rate = 8000;
41 
42  switch (avctx->codec_id) {
43  case CODEC_ID_GSM:
44  avctx->frame_size = GSM_FRAME_SIZE;
45  avctx->block_align = GSM_BLOCK_SIZE;
46  break;
47  case CODEC_ID_GSM_MS:
48  avctx->frame_size = 2 * GSM_FRAME_SIZE;
50  }
51 
53  avctx->coded_frame = &s->frame;
54 
55  return 0;
56 }
57 
58 static int gsm_decode_frame(AVCodecContext *avctx, void *data,
59  int *got_frame_ptr, AVPacket *avpkt)
60 {
61  GSMContext *s = avctx->priv_data;
62  int res;
63  GetBitContext gb;
64  const uint8_t *buf = avpkt->data;
65  int buf_size = avpkt->size;
66  int16_t *samples;
67 
68  if (buf_size < avctx->block_align) {
69  av_log(avctx, AV_LOG_ERROR, "Packet is too small\n");
70  return AVERROR_INVALIDDATA;
71  }
72 
73  /* get output buffer */
74  s->frame.nb_samples = avctx->frame_size;
75  if ((res = avctx->get_buffer(avctx, &s->frame)) < 0) {
76  av_log(avctx, AV_LOG_ERROR, "get_buffer() failed\n");
77  return res;
78  }
79  samples = (int16_t *)s->frame.data[0];
80 
81  switch (avctx->codec_id) {
82  case CODEC_ID_GSM:
83  init_get_bits(&gb, buf, buf_size * 8);
84  if (get_bits(&gb, 4) != 0xd)
85  av_log(avctx, AV_LOG_WARNING, "Missing GSM magic!\n");
86  res = gsm_decode_block(avctx, samples, &gb);
87  if (res < 0)
88  return res;
89  break;
90  case CODEC_ID_GSM_MS:
91  res = ff_msgsm_decode_block(avctx, samples, buf);
92  if (res < 0)
93  return res;
94  }
95 
96  *got_frame_ptr = 1;
97  *(AVFrame *)data = s->frame;
98 
99  return avctx->block_align;
100 }
101 
102 static void gsm_flush(AVCodecContext *avctx)
103 {
104  GSMContext *s = avctx->priv_data;
105  memset(s, 0, sizeof(*s));
106 }
107 
109  .name = "gsm",
110  .type = AVMEDIA_TYPE_AUDIO,
111  .id = CODEC_ID_GSM,
112  .priv_data_size = sizeof(GSMContext),
113  .init = gsm_init,
115  .flush = gsm_flush,
116  .capabilities = CODEC_CAP_DR1,
117  .long_name = NULL_IF_CONFIG_SMALL("GSM"),
118 };
119 
121  .name = "gsm_ms",
122  .type = AVMEDIA_TYPE_AUDIO,
123  .id = CODEC_ID_GSM_MS,
124  .priv_data_size = sizeof(GSMContext),
125  .init = gsm_init,
127  .flush = gsm_flush,
128  .capabilities = CODEC_CAP_DR1,
129  .long_name = NULL_IF_CONFIG_SMALL("GSM Microsoft variant"),
130 };