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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 FFmpeg.
6  *
7  * FFmpeg 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  * FFmpeg 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 FFmpeg; if not, write to the Free Software
19  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
20  */
21 
22 /**
23  * @file
24  * GSM decoder
25  */
26 
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  avctx->channels = 1;
39  if (!avctx->sample_rate)
40  avctx->sample_rate = 8000;
42 
43  switch (avctx->codec_id) {
44  case AV_CODEC_ID_GSM:
45  avctx->frame_size = GSM_FRAME_SIZE;
46  avctx->block_align = GSM_BLOCK_SIZE;
47  break;
48  case AV_CODEC_ID_GSM_MS:
49  avctx->frame_size = 2 * GSM_FRAME_SIZE;
51  }
52 
53  return 0;
54 }
55 
56 static int gsm_decode_frame(AVCodecContext *avctx, void *data,
57  int *got_frame_ptr, AVPacket *avpkt)
58 {
59  AVFrame *frame = data;
60  int res;
61  GetBitContext gb;
62  const uint8_t *buf = avpkt->data;
63  int buf_size = avpkt->size;
64  int16_t *samples;
65 
66  if (buf_size < avctx->block_align) {
67  av_log(avctx, AV_LOG_ERROR, "Packet is too small\n");
68  return AVERROR_INVALIDDATA;
69  }
70 
71  /* get output buffer */
72  frame->nb_samples = avctx->frame_size;
73  if ((res = ff_get_buffer(avctx, frame, 0)) < 0)
74  return res;
75  samples = (int16_t *)frame->data[0];
76 
77  switch (avctx->codec_id) {
78  case AV_CODEC_ID_GSM:
79  init_get_bits(&gb, buf, buf_size * 8);
80  if (get_bits(&gb, 4) != 0xd)
81  av_log(avctx, AV_LOG_WARNING, "Missing GSM magic!\n");
82  res = gsm_decode_block(avctx, samples, &gb);
83  if (res < 0)
84  return res;
85  break;
86  case AV_CODEC_ID_GSM_MS:
87  res = ff_msgsm_decode_block(avctx, samples, buf);
88  if (res < 0)
89  return res;
90  }
91 
92  *got_frame_ptr = 1;
93 
94  return avctx->block_align;
95 }
96 
97 static void gsm_flush(AVCodecContext *avctx)
98 {
99  GSMContext *s = avctx->priv_data;
100  memset(s, 0, sizeof(*s));
101 }
102 
103 #if CONFIG_GSM_DECODER
104 AVCodec ff_gsm_decoder = {
105  .name = "gsm",
106  .type = AVMEDIA_TYPE_AUDIO,
107  .id = AV_CODEC_ID_GSM,
108  .priv_data_size = sizeof(GSMContext),
109  .init = gsm_init,
111  .flush = gsm_flush,
112  .capabilities = CODEC_CAP_DR1,
113  .long_name = NULL_IF_CONFIG_SMALL("GSM"),
114 };
115 #endif
116 #if CONFIG_GSM_MS_DECODER
117 AVCodec ff_gsm_ms_decoder = {
118  .name = "gsm_ms",
119  .type = AVMEDIA_TYPE_AUDIO,
120  .id = AV_CODEC_ID_GSM_MS,
121  .priv_data_size = sizeof(GSMContext),
122  .init = gsm_init,
124  .flush = gsm_flush,
125  .capabilities = CODEC_CAP_DR1,
126  .long_name = NULL_IF_CONFIG_SMALL("GSM Microsoft variant"),
127 };
128 #endif