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 Libav.
7  *
8  * Libav 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  * Libav 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 Libav; 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  avctx->sample_rate = 48000;
74  avctx->bit_rate = 48000 * avctx->channels * (avctx->bits_per_coded_sample + 4) +
75  32 * (48000 / (buf_size * 8 /
76  (avctx->channels *
77  (avctx->bits_per_coded_sample + 4))));
78 
79  return frame_size;
80 }
81 
82 static int s302m_decode_frame(AVCodecContext *avctx, void *data,
83  int *got_frame_ptr, AVPacket *avpkt)
84 {
85  S302MDecodeContext *s = avctx->priv_data;
86  const uint8_t *buf = avpkt->data;
87  int buf_size = avpkt->size;
88  int block_size, ret;
89 
90  int frame_size = s302m_parse_frame_header(avctx, buf, buf_size);
91  if (frame_size < 0)
92  return frame_size;
93 
94  buf_size -= AES3_HEADER_LEN;
95  buf += AES3_HEADER_LEN;
96 
97  /* get output buffer */
98  block_size = (avctx->bits_per_coded_sample + 4) / 4;
99  s->frame.nb_samples = 2 * (buf_size / block_size) / avctx->channels;
100  if ((ret = ff_get_buffer(avctx, &s->frame)) < 0) {
101  av_log(avctx, AV_LOG_ERROR, "get_buffer() failed\n");
102  return ret;
103  }
104 
105  buf_size = (s->frame.nb_samples * avctx->channels / 2) * block_size;
106 
107  if (avctx->bits_per_coded_sample == 24) {
108  uint32_t *o = (uint32_t *)s->frame.data[0];
109  for (; buf_size > 6; buf_size -= 7) {
110  *o++ = (ff_reverse[buf[2]] << 24) |
111  (ff_reverse[buf[1]] << 16) |
112  (ff_reverse[buf[0]] << 8);
113  *o++ = (ff_reverse[buf[6] & 0xf0] << 28) |
114  (ff_reverse[buf[5]] << 20) |
115  (ff_reverse[buf[4]] << 12) |
116  (ff_reverse[buf[3] & 0x0f] << 4);
117  buf += 7;
118  }
119  } else if (avctx->bits_per_coded_sample == 20) {
120  uint32_t *o = (uint32_t *)s->frame.data[0];
121  for (; buf_size > 5; buf_size -= 6) {
122  *o++ = (ff_reverse[buf[2] & 0xf0] << 28) |
123  (ff_reverse[buf[1]] << 20) |
124  (ff_reverse[buf[0]] << 12);
125  *o++ = (ff_reverse[buf[5] & 0xf0] << 28) |
126  (ff_reverse[buf[4]] << 20) |
127  (ff_reverse[buf[3]] << 12);
128  buf += 6;
129  }
130  } else {
131  uint16_t *o = (uint16_t *)s->frame.data[0];
132  for (; buf_size > 4; buf_size -= 5) {
133  *o++ = (ff_reverse[buf[1]] << 8) |
134  ff_reverse[buf[0]];
135  *o++ = (ff_reverse[buf[4] & 0xf0] << 12) |
136  (ff_reverse[buf[3]] << 4) |
137  (ff_reverse[buf[2]] >> 4);
138  buf += 5;
139  }
140  }
141 
142  *got_frame_ptr = 1;
143  *(AVFrame *)data = s->frame;
144 
145  return avpkt->size;
146 }
147 
149 {
150  S302MDecodeContext *s = avctx->priv_data;
151 
153  avctx->coded_frame = &s->frame;
154 
155  return 0;
156 }
157 
158 
160  .name = "s302m",
161  .type = AVMEDIA_TYPE_AUDIO,
162  .id = AV_CODEC_ID_S302M,
163  .priv_data_size = sizeof(S302MDecodeContext),
166  .capabilities = CODEC_CAP_DR1,
167  .long_name = NULL_IF_CONFIG_SMALL("SMPTE 302M"),
168 };