Libav
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 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 static int s302m_parse_frame_header(AVCodecContext *avctx, const uint8_t *buf,
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  avctx->sample_rate = 48000;
70  avctx->bit_rate = 48000 * avctx->channels * (avctx->bits_per_coded_sample + 4) +
71  32 * (48000 / (buf_size * 8 /
72  (avctx->channels *
73  (avctx->bits_per_coded_sample + 4))));
74 
75  return frame_size;
76 }
77 
78 static int s302m_decode_frame(AVCodecContext *avctx, void *data,
79  int *got_frame_ptr, AVPacket *avpkt)
80 {
81  AVFrame *frame = data;
82  const uint8_t *buf = avpkt->data;
83  int buf_size = avpkt->size;
84  int block_size, ret;
85 
86  int frame_size = s302m_parse_frame_header(avctx, buf, buf_size);
87  if (frame_size < 0)
88  return frame_size;
89 
90  buf_size -= AES3_HEADER_LEN;
91  buf += AES3_HEADER_LEN;
92 
93  /* get output buffer */
94  block_size = (avctx->bits_per_coded_sample + 4) / 4;
95  frame->nb_samples = 2 * (buf_size / block_size) / avctx->channels;
96  if ((ret = ff_get_buffer(avctx, frame, 0)) < 0) {
97  av_log(avctx, AV_LOG_ERROR, "get_buffer() failed\n");
98  return ret;
99  }
100 
101  buf_size = (frame->nb_samples * avctx->channels / 2) * block_size;
102 
103  if (avctx->bits_per_coded_sample == 24) {
104  uint32_t *o = (uint32_t *)frame->data[0];
105  for (; buf_size > 6; buf_size -= 7) {
106  *o++ = (ff_reverse[buf[2]] << 24) |
107  (ff_reverse[buf[1]] << 16) |
108  (ff_reverse[buf[0]] << 8);
109  *o++ = (ff_reverse[buf[6] & 0xf0] << 28) |
110  (ff_reverse[buf[5]] << 20) |
111  (ff_reverse[buf[4]] << 12) |
112  (ff_reverse[buf[3] & 0x0f] << 4);
113  buf += 7;
114  }
115  } else if (avctx->bits_per_coded_sample == 20) {
116  uint32_t *o = (uint32_t *)frame->data[0];
117  for (; buf_size > 5; buf_size -= 6) {
118  *o++ = (ff_reverse[buf[2] & 0xf0] << 28) |
119  (ff_reverse[buf[1]] << 20) |
120  (ff_reverse[buf[0]] << 12);
121  *o++ = (ff_reverse[buf[5] & 0xf0] << 28) |
122  (ff_reverse[buf[4]] << 20) |
123  (ff_reverse[buf[3]] << 12);
124  buf += 6;
125  }
126  } else {
127  uint16_t *o = (uint16_t *)frame->data[0];
128  for (; buf_size > 4; buf_size -= 5) {
129  *o++ = (ff_reverse[buf[1]] << 8) |
130  ff_reverse[buf[0]];
131  *o++ = (ff_reverse[buf[4] & 0xf0] << 12) |
132  (ff_reverse[buf[3]] << 4) |
133  (ff_reverse[buf[2]] >> 4);
134  buf += 5;
135  }
136  }
137 
138  *got_frame_ptr = 1;
139 
140  return avpkt->size;
141 }
142 
144  .name = "s302m",
145  .long_name = NULL_IF_CONFIG_SMALL("SMPTE 302M"),
146  .type = AVMEDIA_TYPE_AUDIO,
147  .id = AV_CODEC_ID_S302M,
148  .decode = s302m_decode_frame,
149  .capabilities = CODEC_CAP_DR1,
150 };
#define AVERROR_INVALIDDATA
Invalid data found when processing input.
Definition: error.h:54
This structure describes decoded (raw) audio or video data.
Definition: frame.h:135
static int s302m_parse_frame_header(AVCodecContext *avctx, const uint8_t *buf, int buf_size)
Definition: s302m.c:31
int size
Definition: avcodec.h:974
void av_log(void *avcl, int level, const char *fmt,...) av_printf_format(3
Send the specified message to the log if the level is less than or equal to the current av_log_level...
AVCodec.
Definition: avcodec.h:2796
uint8_t bits
Definition: crc.c:251
enum AVSampleFormat sample_fmt
audio sample format
Definition: avcodec.h:1799
uint8_t
const char * name
Name of the codec implementation.
Definition: avcodec.h:2803
#define CODEC_CAP_DR1
Codec uses get_buffer() for allocating buffers and supports custom allocators.
Definition: avcodec.h:684
const char data[16]
Definition: mxf.c:70
int bits_per_coded_sample
bits per sample/pixel from the demuxer (needed for huffyuv).
Definition: avcodec.h:2507
signed 32 bits
Definition: samplefmt.h:65
static const uint8_t frame_size[4]
Definition: g723_1_data.h:47
#define AV_LOG_ERROR
Something went wrong and cannot losslessly be recovered.
Definition: log.h:123
AVCodec ff_s302m_decoder
Definition: s302m.c:143
#define NULL_IF_CONFIG_SMALL(x)
Return NULL if CONFIG_SMALL is true, otherwise the argument without modification. ...
Definition: internal.h:150
Libavcodec external API header.
int bit_rate
the average bitrate
Definition: avcodec.h:1114
if(ac->has_optimized_func)
int sample_rate
samples per second
Definition: avcodec.h:1791
main external API structure.
Definition: avcodec.h:1050
int ff_get_buffer(AVCodecContext *avctx, AVFrame *frame, int flags)
Get a buffer for a frame.
Definition: utils.c:612
uint8_t * data
Definition: avcodec.h:973
#define AES3_HEADER_LEN
Definition: s302m.c:29
common internal api header.
signed 16 bits
Definition: samplefmt.h:64
#define AV_RB32(x)
Definition: intreadwrite.h:232
int channels
number of audio channels
Definition: avcodec.h:1792
static int s302m_decode_frame(AVCodecContext *avctx, void *data, int *got_frame_ptr, AVPacket *avpkt)
Definition: s302m.c:78
const uint8_t ff_reverse[256]
Definition: mathtables.c:72
This structure stores compressed data.
Definition: avcodec.h:950
int nb_samples
number of audio samples (per channel) described by this frame
Definition: frame.h:179
uint8_t * data[AV_NUM_DATA_POINTERS]
pointer to the picture/channel planes.
Definition: frame.h:141
for(j=16;j >0;--j)