FFmpeg
 All Data Structures Namespaces Files Functions Variables Typedefs Enumerations Enumerator Macros Groups Pages
s302m.c
Go to the documentation of this file.
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 
32  int buf_size)
33 {
34  uint32_t h;
35  int frame_size, channels, bits;
36 
37  if (buf_size <= AES3_HEADER_LEN) {
38  av_log(avctx, AV_LOG_ERROR, "frame is too short\n");
39  return AVERROR_INVALIDDATA;
40  }
41 
42  /*
43  * AES3 header :
44  * size: 16
45  * number channels 2
46  * channel_id 8
47  * bits per samples 2
48  * alignments 4
49  */
50 
51  h = AV_RB32(buf);
52  frame_size = (h >> 16) & 0xffff;
53  channels = ((h >> 14) & 0x0003) * 2 + 2;
54  bits = ((h >> 4) & 0x0003) * 4 + 16;
55 
56  if (AES3_HEADER_LEN + frame_size != buf_size || bits > 24) {
57  av_log(avctx, AV_LOG_ERROR, "frame has invalid header\n");
58  return AVERROR_INVALIDDATA;
59  }
60 
61  /* Set output properties */
62  avctx->bits_per_coded_sample = bits;
63  if (bits > 16)
65  else
67 
68  avctx->channels = channels;
69  switch(channels) {
70  case 2:
72  break;
73  case 4:
75  break;
76  case 6:
78  break;
79  case 8:
81  }
82  avctx->sample_rate = 48000;
83  avctx->bit_rate = 48000 * avctx->channels * (avctx->bits_per_coded_sample + 4) +
84  32 * (48000 / (buf_size * 8 /
85  (avctx->channels *
86  (avctx->bits_per_coded_sample + 4))));
87 
88  return frame_size;
89 }
90 
91 static int s302m_decode_frame(AVCodecContext *avctx, void *data,
92  int *got_frame_ptr, AVPacket *avpkt)
93 {
94  AVFrame *frame = data;
95  const uint8_t *buf = avpkt->data;
96  int buf_size = avpkt->size;
97  int block_size, ret;
98 
99  int frame_size = s302m_parse_frame_header(avctx, buf, buf_size);
100  if (frame_size < 0)
101  return frame_size;
102 
103  buf_size -= AES3_HEADER_LEN;
104  buf += AES3_HEADER_LEN;
105 
106  /* get output buffer */
107  block_size = (avctx->bits_per_coded_sample + 4) / 4;
108  frame->nb_samples = 2 * (buf_size / block_size) / avctx->channels;
109  if ((ret = ff_get_buffer(avctx, frame, 0)) < 0)
110  return ret;
111 
112  buf_size = (frame->nb_samples * avctx->channels / 2) * block_size;
113 
114  if (avctx->bits_per_coded_sample == 24) {
115  uint32_t *o = (uint32_t *)frame->data[0];
116  for (; buf_size > 6; buf_size -= 7) {
117  *o++ = (ff_reverse[buf[2]] << 24) |
118  (ff_reverse[buf[1]] << 16) |
119  (ff_reverse[buf[0]] << 8);
120  *o++ = (ff_reverse[buf[6] & 0xf0] << 28) |
121  (ff_reverse[buf[5]] << 20) |
122  (ff_reverse[buf[4]] << 12) |
123  (ff_reverse[buf[3] & 0x0f] << 4);
124  buf += 7;
125  }
126  } else if (avctx->bits_per_coded_sample == 20) {
127  uint32_t *o = (uint32_t *)frame->data[0];
128  for (; buf_size > 5; buf_size -= 6) {
129  *o++ = (ff_reverse[buf[2] & 0xf0] << 28) |
130  (ff_reverse[buf[1]] << 20) |
131  (ff_reverse[buf[0]] << 12);
132  *o++ = (ff_reverse[buf[5] & 0xf0] << 28) |
133  (ff_reverse[buf[4]] << 20) |
134  (ff_reverse[buf[3]] << 12);
135  buf += 6;
136  }
137  } else {
138  uint16_t *o = (uint16_t *)frame->data[0];
139  for (; buf_size > 4; buf_size -= 5) {
140  *o++ = (ff_reverse[buf[1]] << 8) |
141  ff_reverse[buf[0]];
142  *o++ = (ff_reverse[buf[4] & 0xf0] << 12) |
143  (ff_reverse[buf[3]] << 4) |
144  (ff_reverse[buf[2]] >> 4);
145  buf += 5;
146  }
147  }
148 
149  *got_frame_ptr = 1;
150 
151  return avpkt->size;
152 }
153 
155  .name = "s302m",
156  .type = AVMEDIA_TYPE_AUDIO,
157  .id = AV_CODEC_ID_S302M,
158  .decode = s302m_decode_frame,
159  .capabilities = CODEC_CAP_DR1,
160  .long_name = NULL_IF_CONFIG_SMALL("SMPTE 302M"),
161 };