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s302m.c
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1 /*
2  * SMPTE 302M decoder
3  * Copyright (c) 2008 Laurent Aimar <fenrir@videolan.org>
4  * Copyright (c) 2009 Baptiste Coudurier <baptiste.coudurier@gmail.com>
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 #include "libavutil/intreadwrite.h"
24 #include "libavutil/log.h"
25 #include "avcodec.h"
26 #include "internal.h"
27 #include "mathops.h"
28 
29 #define AES3_HEADER_LEN 4
30 
31 typedef struct S302MDecodeContext {
34 
35 static int s302m_parse_frame_header(AVCodecContext *avctx, const uint8_t *buf,
36  int buf_size)
37 {
38  uint32_t h;
39  int frame_size, channels, bits;
40 
41  if (buf_size <= AES3_HEADER_LEN) {
42  av_log(avctx, AV_LOG_ERROR, "frame is too short\n");
43  return AVERROR_INVALIDDATA;
44  }
45 
46  /*
47  * AES3 header :
48  * size: 16
49  * number channels 2
50  * channel_id 8
51  * bits per samples 2
52  * alignments 4
53  */
54 
55  h = AV_RB32(buf);
56  frame_size = (h >> 16) & 0xffff;
57  channels = ((h >> 14) & 0x0003) * 2 + 2;
58  bits = ((h >> 4) & 0x0003) * 4 + 16;
59 
60  if (AES3_HEADER_LEN + frame_size != buf_size || bits > 24) {
61  av_log(avctx, AV_LOG_ERROR, "frame has invalid header\n");
62  return AVERROR_INVALIDDATA;
63  }
64 
65  /* Set output properties */
66  avctx->bits_per_coded_sample = bits;
67  if (bits > 16)
69  else
71 
72  avctx->channels = channels;
73  switch(channels) {
74  case 2:
76  break;
77  case 4:
79  break;
80  case 6:
82  break;
83  case 8:
85  }
86  avctx->sample_rate = 48000;
87  avctx->bit_rate = 48000 * avctx->channels * (avctx->bits_per_coded_sample + 4) +
88  32 * (48000 / (buf_size * 8 /
89  (avctx->channels *
90  (avctx->bits_per_coded_sample + 4))));
91 
92  return frame_size;
93 }
94 
95 static int s302m_decode_frame(AVCodecContext *avctx, void *data,
96  int *got_frame_ptr, AVPacket *avpkt)
97 {
98  S302MDecodeContext *s = avctx->priv_data;
99  const uint8_t *buf = avpkt->data;
100  int buf_size = avpkt->size;
101  int block_size, ret;
102 
103  int frame_size = s302m_parse_frame_header(avctx, buf, buf_size);
104  if (frame_size < 0)
105  return frame_size;
106 
107  buf_size -= AES3_HEADER_LEN;
108  buf += AES3_HEADER_LEN;
109 
110  /* get output buffer */
111  block_size = (avctx->bits_per_coded_sample + 4) / 4;
112  s->frame.nb_samples = 2 * (buf_size / block_size) / avctx->channels;
113  if ((ret = ff_get_buffer(avctx, &s->frame)) < 0) {
114  av_log(avctx, AV_LOG_ERROR, "get_buffer() failed\n");
115  return ret;
116  }
117 
118  buf_size = (s->frame.nb_samples * avctx->channels / 2) * block_size;
119 
120  if (avctx->bits_per_coded_sample == 24) {
121  uint32_t *o = (uint32_t *)s->frame.data[0];
122  for (; buf_size > 6; buf_size -= 7) {
123  *o++ = (ff_reverse[buf[2]] << 24) |
124  (ff_reverse[buf[1]] << 16) |
125  (ff_reverse[buf[0]] << 8);
126  *o++ = (ff_reverse[buf[6] & 0xf0] << 28) |
127  (ff_reverse[buf[5]] << 20) |
128  (ff_reverse[buf[4]] << 12) |
129  (ff_reverse[buf[3] & 0x0f] << 4);
130  buf += 7;
131  }
132  } else if (avctx->bits_per_coded_sample == 20) {
133  uint32_t *o = (uint32_t *)s->frame.data[0];
134  for (; buf_size > 5; buf_size -= 6) {
135  *o++ = (ff_reverse[buf[2] & 0xf0] << 28) |
136  (ff_reverse[buf[1]] << 20) |
137  (ff_reverse[buf[0]] << 12);
138  *o++ = (ff_reverse[buf[5] & 0xf0] << 28) |
139  (ff_reverse[buf[4]] << 20) |
140  (ff_reverse[buf[3]] << 12);
141  buf += 6;
142  }
143  } else {
144  uint16_t *o = (uint16_t *)s->frame.data[0];
145  for (; buf_size > 4; buf_size -= 5) {
146  *o++ = (ff_reverse[buf[1]] << 8) |
147  ff_reverse[buf[0]];
148  *o++ = (ff_reverse[buf[4] & 0xf0] << 12) |
149  (ff_reverse[buf[3]] << 4) |
150  (ff_reverse[buf[2]] >> 4);
151  buf += 5;
152  }
153  }
154 
155  *got_frame_ptr = 1;
156  *(AVFrame *)data = s->frame;
157 
158  return avpkt->size;
159 }
160 
162 {
163  S302MDecodeContext *s = avctx->priv_data;
164 
166  avctx->coded_frame = &s->frame;
167 
168  return 0;
169 }
170 
171 
173  .name = "s302m",
174  .type = AVMEDIA_TYPE_AUDIO,
175  .id = AV_CODEC_ID_S302M,
176  .priv_data_size = sizeof(S302MDecodeContext),
179  .capabilities = CODEC_CAP_DR1,
180  .long_name = NULL_IF_CONFIG_SMALL("SMPTE 302M"),
181 };