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 "internal.h"
29 #include "get_bits.h"
30 #include "msgsmdec.h"
31 
32 #include "gsmdec_template.c"
33 
34 static av_cold int gsm_init(AVCodecContext *avctx)
35 {
36  GSMContext *s = avctx->priv_data;
37 
38  avctx->channels = 1;
39  if (!avctx->sample_rate)
40  avctx->sample_rate = 8000;
42 
43  switch (avctx->codec_id) {
44  case CODEC_ID_GSM:
45  avctx->frame_size = GSM_FRAME_SIZE;
46  avctx->block_align = GSM_BLOCK_SIZE;
47  break;
48  case CODEC_ID_GSM_MS:
49  avctx->frame_size = 2 * GSM_FRAME_SIZE;
51  }
52 
54  avctx->coded_frame = &s->frame;
55 
56  return 0;
57 }
58 
59 static int gsm_decode_frame(AVCodecContext *avctx, void *data,
60  int *got_frame_ptr, AVPacket *avpkt)
61 {
62  GSMContext *s = avctx->priv_data;
63  int res;
64  GetBitContext gb;
65  const uint8_t *buf = avpkt->data;
66  int buf_size = avpkt->size;
67  int16_t *samples;
68 
69  if (buf_size < avctx->block_align) {
70  av_log(avctx, AV_LOG_ERROR, "Packet is too small\n");
71  return AVERROR_INVALIDDATA;
72  }
73 
74  /* get output buffer */
75  s->frame.nb_samples = avctx->frame_size;
76  if ((res = ff_get_buffer(avctx, &s->frame)) < 0) {
77  av_log(avctx, AV_LOG_ERROR, "get_buffer() failed\n");
78  return res;
79  }
80  samples = (int16_t *)s->frame.data[0];
81 
82  switch (avctx->codec_id) {
83  case CODEC_ID_GSM:
84  init_get_bits(&gb, buf, buf_size * 8);
85  if (get_bits(&gb, 4) != 0xd)
86  av_log(avctx, AV_LOG_WARNING, "Missing GSM magic!\n");
87  res = gsm_decode_block(avctx, samples, &gb);
88  if (res < 0)
89  return res;
90  break;
91  case CODEC_ID_GSM_MS:
92  res = ff_msgsm_decode_block(avctx, samples, buf);
93  if (res < 0)
94  return res;
95  }
96 
97  *got_frame_ptr = 1;
98  *(AVFrame *)data = s->frame;
99 
100  return avctx->block_align;
101 }
102 
103 static void gsm_flush(AVCodecContext *avctx)
104 {
105  GSMContext *s = avctx->priv_data;
106  memset(s, 0, sizeof(*s));
107 }
108 
110  .name = "gsm",
111  .type = AVMEDIA_TYPE_AUDIO,
112  .id = CODEC_ID_GSM,
113  .priv_data_size = sizeof(GSMContext),
114  .init = gsm_init,
116  .flush = gsm_flush,
117  .capabilities = CODEC_CAP_DR1,
118  .long_name = NULL_IF_CONFIG_SMALL("GSM"),
119 };
120 
122  .name = "gsm_ms",
123  .type = AVMEDIA_TYPE_AUDIO,
124  .id = CODEC_ID_GSM_MS,
125  .priv_data_size = sizeof(GSMContext),
126  .init = gsm_init,
128  .flush = gsm_flush,
129  .capabilities = CODEC_CAP_DR1,
130  .long_name = NULL_IF_CONFIG_SMALL("GSM Microsoft variant"),
131 };