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 "avcodec.h"
25 #include "internal.h"
26 
27 #define AES3_HEADER_LEN 4
28 
29 typedef struct S302MDecodeContext {
32 
33 static int s302m_parse_frame_header(AVCodecContext *avctx, const uint8_t *buf,
34  int buf_size)
35 {
36  uint32_t h;
37  int frame_size, channels, bits;
38 
39  if (buf_size <= AES3_HEADER_LEN) {
40  av_log(avctx, AV_LOG_ERROR, "frame is too short\n");
41  return AVERROR_INVALIDDATA;
42  }
43 
44  /*
45  * AES3 header :
46  * size: 16
47  * number channels 2
48  * channel_id 8
49  * bits per samples 2
50  * alignments 4
51  */
52 
53  h = AV_RB32(buf);
54  frame_size = (h >> 16) & 0xffff;
55  channels = ((h >> 14) & 0x0003) * 2 + 2;
56  bits = ((h >> 4) & 0x0003) * 4 + 16;
57 
58  if (AES3_HEADER_LEN + frame_size != buf_size || bits > 24) {
59  av_log(avctx, AV_LOG_ERROR, "frame has invalid header\n");
60  return AVERROR_INVALIDDATA;
61  }
62 
63  /* Set output properties */
64  avctx->bits_per_coded_sample = bits;
65  if (bits > 16)
67  else
69 
70  avctx->channels = channels;
71  avctx->sample_rate = 48000;
72  avctx->bit_rate = 48000 * avctx->channels * (avctx->bits_per_coded_sample + 4) +
73  32 * (48000 / (buf_size * 8 /
74  (avctx->channels *
75  (avctx->bits_per_coded_sample + 4))));
76 
77  return frame_size;
78 }
79 
80 static int s302m_decode_frame(AVCodecContext *avctx, void *data,
81  int *got_frame_ptr, AVPacket *avpkt)
82 {
83  S302MDecodeContext *s = avctx->priv_data;
84  const uint8_t *buf = avpkt->data;
85  int buf_size = avpkt->size;
86  int block_size, ret;
87 
88  int frame_size = s302m_parse_frame_header(avctx, buf, buf_size);
89  if (frame_size < 0)
90  return frame_size;
91 
92  buf_size -= AES3_HEADER_LEN;
93  buf += AES3_HEADER_LEN;
94 
95  /* get output buffer */
96  block_size = (avctx->bits_per_coded_sample + 4) / 4;
97  s->frame.nb_samples = 2 * (buf_size / block_size) / avctx->channels;
98  if ((ret = ff_get_buffer(avctx, &s->frame)) < 0) {
99  av_log(avctx, AV_LOG_ERROR, "get_buffer() failed\n");
100  return ret;
101  }
102 
103  buf_size = (s->frame.nb_samples * avctx->channels / 2) * block_size;
104 
105  if (avctx->bits_per_coded_sample == 24) {
106  uint32_t *o = (uint32_t *)s->frame.data[0];
107  for (; buf_size > 6; buf_size -= 7) {
108  *o++ = (av_reverse[buf[2]] << 24) |
109  (av_reverse[buf[1]] << 16) |
110  (av_reverse[buf[0]] << 8);
111  *o++ = (av_reverse[buf[6] & 0xf0] << 28) |
112  (av_reverse[buf[5]] << 20) |
113  (av_reverse[buf[4]] << 12) |
114  (av_reverse[buf[3] & 0x0f] << 4);
115  buf += 7;
116  }
117  } else if (avctx->bits_per_coded_sample == 20) {
118  uint32_t *o = (uint32_t *)s->frame.data[0];
119  for (; buf_size > 5; buf_size -= 6) {
120  *o++ = (av_reverse[buf[2] & 0xf0] << 28) |
121  (av_reverse[buf[1]] << 20) |
122  (av_reverse[buf[0]] << 12);
123  *o++ = (av_reverse[buf[5] & 0xf0] << 28) |
124  (av_reverse[buf[4]] << 20) |
125  (av_reverse[buf[3]] << 12);
126  buf += 6;
127  }
128  } else {
129  uint16_t *o = (uint16_t *)s->frame.data[0];
130  for (; buf_size > 4; buf_size -= 5) {
131  *o++ = (av_reverse[buf[1]] << 8) |
132  av_reverse[buf[0]];
133  *o++ = (av_reverse[buf[4] & 0xf0] << 12) |
134  (av_reverse[buf[3]] << 4) |
135  (av_reverse[buf[2]] >> 4);
136  buf += 5;
137  }
138  }
139 
140  *got_frame_ptr = 1;
141  *(AVFrame *)data = s->frame;
142 
143  return avpkt->size;
144 }
145 
147 {
148  S302MDecodeContext *s = avctx->priv_data;
149 
151  avctx->coded_frame = &s->frame;
152 
153  return 0;
154 }
155 
156 
158  .name = "s302m",
159  .type = AVMEDIA_TYPE_AUDIO,
160  .id = CODEC_ID_S302M,
161  .priv_data_size = sizeof(S302MDecodeContext),
164  .capabilities = CODEC_CAP_DR1,
165  .long_name = NULL_IF_CONFIG_SMALL("SMPTE 302M"),
166 };