Libav
spdifdec.c
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1 /*
2  * IEC 61937 demuxer
3  * Copyright (c) 2010 Anssi Hannula <anssi.hannula at iki.fi>
4  *
5  * This file is part of Libav.
6  *
7  * Libav is free software; you can redistribute it and/or
8  * modify it under the terms of the GNU Lesser General Public
9  * License as published by the Free Software Foundation; either
10  * version 2.1 of the License, or (at your option) any later version.
11  *
12  * Libav is distributed in the hope that it will be useful,
13  * but WITHOUT ANY WARRANTY; without even the implied warranty of
14  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
15  * Lesser General Public License for more details.
16  *
17  * You should have received a copy of the GNU Lesser General Public
18  * License along with Libav; if not, write to the Free Software
19  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
20  */
21 
28 #include "avformat.h"
29 #include "spdif.h"
30 #include "libavcodec/ac3.h"
31 #include "libavcodec/aacadtsdec.h"
32 
34  enum IEC61937DataType data_type,
35  const char *buf, int *offset,
36  enum AVCodecID *codec)
37 {
38  AACADTSHeaderInfo aac_hdr;
39  GetBitContext gbc;
40 
41  switch (data_type & 0xff) {
42  case IEC61937_AC3:
43  *offset = AC3_FRAME_SIZE << 2;
44  *codec = AV_CODEC_ID_AC3;
45  break;
47  *offset = spdif_mpeg_pkt_offset[1][0];
48  *codec = AV_CODEC_ID_MP1;
49  break;
51  *offset = spdif_mpeg_pkt_offset[1][0];
52  *codec = AV_CODEC_ID_MP3;
53  break;
54  case IEC61937_MPEG2_EXT:
55  *offset = 4608;
56  *codec = AV_CODEC_ID_MP3;
57  break;
58  case IEC61937_MPEG2_AAC:
59  init_get_bits(&gbc, buf, AAC_ADTS_HEADER_SIZE * 8);
60  if (avpriv_aac_parse_header(&gbc, &aac_hdr)) {
61  if (s) /* be silent during a probe */
62  av_log(s, AV_LOG_ERROR, "Invalid AAC packet in IEC 61937\n");
63  return AVERROR_INVALIDDATA;
64  }
65  *offset = aac_hdr.samples << 2;
66  *codec = AV_CODEC_ID_AAC;
67  break;
69  *offset = spdif_mpeg_pkt_offset[0][0];
70  *codec = AV_CODEC_ID_MP1;
71  break;
73  *offset = spdif_mpeg_pkt_offset[0][1];
74  *codec = AV_CODEC_ID_MP2;
75  break;
77  *offset = spdif_mpeg_pkt_offset[0][2];
78  *codec = AV_CODEC_ID_MP3;
79  break;
80  case IEC61937_DTS1:
81  *offset = 2048;
82  *codec = AV_CODEC_ID_DTS;
83  break;
84  case IEC61937_DTS2:
85  *offset = 4096;
86  *codec = AV_CODEC_ID_DTS;
87  break;
88  case IEC61937_DTS3:
89  *offset = 8192;
90  *codec = AV_CODEC_ID_DTS;
91  break;
92  default:
93  if (s) { /* be silent during a probe */
94  avpriv_request_sample(s, "Data type 0x%04x in IEC 61937",
95  data_type);
96  }
97  return AVERROR_PATCHWELCOME;
98  }
99  return 0;
100 }
101 
102 /* Largest offset between bursts we currently handle, i.e. AAC with
103  aac_hdr.samples = 4096 */
104 #define SPDIF_MAX_OFFSET 16384
105 
106 static int spdif_probe(AVProbeData *p)
107 {
108  const uint8_t *buf = p->buf;
109  const uint8_t *probe_end = p->buf + FFMIN(2 * SPDIF_MAX_OFFSET, p->buf_size - 1);
110  const uint8_t *expected_code = buf + 7;
111  uint32_t state = 0;
112  int sync_codes = 0;
113  int consecutive_codes = 0;
114  int offset;
115  enum AVCodecID codec;
116 
117  for (; buf < probe_end; buf++) {
118  state = (state << 8) | *buf;
119 
120  if (state == (AV_BSWAP16C(SYNCWORD1) << 16 | AV_BSWAP16C(SYNCWORD2))
121  && buf[1] < 0x37) {
122  sync_codes++;
123 
124  if (buf == expected_code) {
125  if (++consecutive_codes >= 2)
126  return AVPROBE_SCORE_MAX;
127  } else
128  consecutive_codes = 0;
129 
130  if (buf + 4 + AAC_ADTS_HEADER_SIZE > p->buf + p->buf_size)
131  break;
132 
133  /* continue probing to find more sync codes */
134  probe_end = FFMIN(buf + SPDIF_MAX_OFFSET, p->buf + p->buf_size - 1);
135 
136  /* skip directly to the next sync code */
137  if (!spdif_get_offset_and_codec(NULL, (buf[2] << 8) | buf[1],
138  &buf[5], &offset, &codec)) {
139  if (buf + offset >= p->buf + p->buf_size)
140  break;
141  expected_code = buf + offset;
142  buf = expected_code - 7;
143  }
144  }
145  }
146 
147  if (!sync_codes)
148  return 0;
149 
150  if (sync_codes >= 6)
151  /* good amount of sync codes but with unexpected offsets */
153 
154  /* some sync codes were found */
155  return AVPROBE_SCORE_EXTENSION / 4;
156 }
157 
159 {
161  return 0;
162 }
163 
165 {
166  AVIOContext *pb = s->pb;
167  enum IEC61937DataType data_type;
168  enum AVCodecID codec_id;
169  uint32_t state = 0;
170  int pkt_size_bits, offset, ret;
171 
172  while (state != (AV_BSWAP16C(SYNCWORD1) << 16 | AV_BSWAP16C(SYNCWORD2))) {
173  state = (state << 8) | avio_r8(pb);
174  if (pb->eof_reached)
175  return AVERROR_EOF;
176  }
177 
178  data_type = avio_rl16(pb);
179  pkt_size_bits = avio_rl16(pb);
180 
181  if (pkt_size_bits % 16)
182  avpriv_request_sample(s, "Packet not ending at a 16-bit boundary");
183 
184  ret = av_new_packet(pkt, FFALIGN(pkt_size_bits, 16) >> 3);
185  if (ret)
186  return ret;
187 
188  pkt->pos = avio_tell(pb) - BURST_HEADER_SIZE;
189 
190  if (avio_read(pb, pkt->data, pkt->size) < pkt->size) {
191  av_free_packet(pkt);
192  return AVERROR_EOF;
193  }
194  ff_spdif_bswap_buf16((uint16_t *)pkt->data, (uint16_t *)pkt->data, pkt->size >> 1);
195 
196  ret = spdif_get_offset_and_codec(s, data_type, pkt->data,
197  &offset, &codec_id);
198  if (ret) {
199  av_free_packet(pkt);
200  return ret;
201  }
202 
203  /* skip over the padding to the beginning of the next frame */
204  avio_skip(pb, offset - pkt->size - BURST_HEADER_SIZE);
205 
206  if (!s->nb_streams) {
207  /* first packet, create a stream */
209  if (!st) {
210  av_free_packet(pkt);
211  return AVERROR(ENOMEM);
212  }
214  st->codec->codec_id = codec_id;
215  } else if (codec_id != s->streams[0]->codec->codec_id) {
216  avpriv_report_missing_feature(s, "Codec change in IEC 61937");
217  return AVERROR_PATCHWELCOME;
218  }
219 
220  if (!s->bit_rate && s->streams[0]->codec->sample_rate)
221  /* stream bitrate matches 16-bit stereo PCM bitrate for currently
222  supported codecs */
223  s->bit_rate = 2 * 16 * s->streams[0]->codec->sample_rate;
224 
225  return 0;
226 }
227 
229  .name = "spdif",
230  .long_name = NULL_IF_CONFIG_SMALL("IEC 61937 (compressed data in S/PDIF)"),
231  .read_probe = spdif_probe,
232  .read_header = spdif_read_header,
233  .read_packet = spdif_read_packet,
234  .flags = AVFMT_GENERIC_INDEX,
235 };
static int spdif_get_offset_and_codec(AVFormatContext *s, enum IEC61937DataType data_type, const char *buf, int *offset, enum AVCodecID *codec)
Definition: spdifdec.c:33
Bytestream IO Context.
Definition: avio.h:68
#define AVERROR_INVALIDDATA
Invalid data found when processing input.
Definition: error.h:54
void av_free_packet(AVPacket *pkt)
Free a packet.
Definition: avpacket.c:242
int64_t pos
byte position in stream, -1 if unknown
Definition: avcodec.h:1002
#define BURST_HEADER_SIZE
Definition: spdif.h:29
MPEG-2, layer-1 low sampling frequency.
Definition: spdif.h:37
int size
Definition: avcodec.h:974
static int spdif_read_header(AVFormatContext *s)
Definition: spdifdec.c:158
IEC61937DataType
Definition: spdif.h:31
void ff_spdif_bswap_buf16(uint16_t *dst, const uint16_t *src, int w)
Definition: spdif.c:26
int ctx_flags
Format-specific flags, see AVFMTCTX_xx.
Definition: avformat.h:916
#define FFALIGN(x, a)
Definition: common.h:62
Format I/O context.
Definition: avformat.h:871
void void avpriv_request_sample(void *avc, const char *msg,...) av_printf_format(2
Log a generic warning message about a missing feature.
MPEG-2 AAC ADTS.
Definition: spdif.h:36
uint8_t
static int spdif_probe(AVProbeData *p)
Definition: spdifdec.c:106
#define AVFMTCTX_NOHEADER
signal that no header is present (streams are added dynamically)
Definition: avformat.h:850
AVStream ** streams
A list of all streams in the file.
Definition: avformat.h:935
uint8_t * data
Definition: avcodec.h:973
#define AVERROR_EOF
End of file.
Definition: error.h:51
DTS type II (1024 samples)
Definition: spdif.h:41
static av_always_inline int64_t avio_tell(AVIOContext *s)
ftell() equivalent for AVIOContext.
Definition: avio.h:219
int avio_read(AVIOContext *s, unsigned char *buf, int size)
Read size bytes from AVIOContext into buf.
Definition: aviobuf.c:446
#define AV_BSWAP16C(x)
Definition: bswap.h:53
int av_new_packet(AVPacket *pkt, int size)
Allocate the payload of a packet and initialize its fields with default values.
Definition: avpacket.c:80
AVCodecID
Identify the syntax and semantics of the bitstream.
Definition: avcodec.h:105
#define AV_LOG_ERROR
Something went wrong and cannot losslessly be recovered.
Definition: log.h:123
DTS type III (2048 samples)
Definition: spdif.h:42
#define AVERROR(e)
Definition: error.h:43
#define NULL_IF_CONFIG_SMALL(x)
Return NULL if CONFIG_SMALL is true, otherwise the argument without modification. ...
Definition: internal.h:142
preferred ID for decoding MPEG audio layer 1, 2 or 3
Definition: avcodec.h:369
void av_log(void *avcl, int level, const char *fmt,...)
Definition: log.c:148
AVStream * avformat_new_stream(AVFormatContext *s, AVCodec *c)
Add a new stream to a media file.
Definition: utils.c:2662
MPEG-1 layer 2 or 3 data or MPEG-2 without extension.
Definition: spdif.h:34
MPEG-2, layer-3 low sampling frequency.
Definition: spdif.h:39
enum AVCodecID codec_id
Definition: mov_chan.c:432
MPEG-1 layer 1.
Definition: spdif.h:33
int avio_r8(AVIOContext *s)
Definition: aviobuf.c:437
AVCodecContext * codec
Codec context associated with this stream.
Definition: avformat.h:702
int buf_size
Size of buf except extra allocated bytes.
Definition: avformat.h:391
unsigned char * buf
Buffer must have AVPROBE_PADDING_SIZE of extra allocated bytes filled with zero.
Definition: avformat.h:390
unsigned int nb_streams
Number of elements in AVFormatContext.streams.
Definition: avformat.h:923
#define FFMIN(a, b)
Definition: common.h:57
static av_always_inline int64_t avio_skip(AVIOContext *s, int64_t offset)
Skip given number of bytes forward.
Definition: avio.h:210
#define SPDIF_MAX_OFFSET
Definition: spdifdec.c:104
uint32_t samples
Definition: aacadtsdec.h:33
#define SYNCWORD2
Definition: spdif.h:28
Stream structure.
Definition: avformat.h:683
#define AVERROR_PATCHWELCOME
Not yet implemented in Libav, patches welcome.
Definition: error.h:57
NULL
Definition: eval.c:55
#define AAC_ADTS_HEADER_SIZE
Definition: aacadtsdec.h:29
enum AVMediaType codec_type
Definition: avcodec.h:1062
enum AVCodecID codec_id
Definition: avcodec.h:1065
int sample_rate
samples per second
Definition: avcodec.h:1779
AVIOContext * pb
I/O context.
Definition: avformat.h:913
int avpriv_aac_parse_header(GetBitContext *gbc, AACADTSHeaderInfo *hdr)
Parse AAC frame header.
Definition: aacadtsdec.c:29
#define AVFMT_GENERIC_INDEX
Use generic index building code.
Definition: avformat.h:408
static int spdif_read_packet(AVFormatContext *s, AVPacket *pkt)
Definition: spdifdec.c:164
static int init_get_bits(GetBitContext *s, const uint8_t *buffer, int bit_size)
Initialize GetBitContext.
Definition: get_bits.h:375
#define AVPROBE_SCORE_EXTENSION
score for file extension
Definition: avformat.h:394
DTS type I (512 samples)
Definition: spdif.h:40
This structure contains the data a format has to probe a file.
Definition: avformat.h:388
void avpriv_report_missing_feature(void *avc, const char *msg,...) av_printf_format(2
Log a generic warning message about a missing feature.
static uint32_t state
Definition: trasher.c:27
MPEG-2, layer-2 low sampling frequency.
Definition: spdif.h:38
#define AC3_FRAME_SIZE
Definition: ac3.h:37
#define AVPROBE_SCORE_MAX
maximum score
Definition: avformat.h:395
unsigned int avio_rl16(AVIOContext *s)
Definition: aviobuf.c:542
Main libavformat public API header.
MPEG-2 data with extension.
Definition: spdif.h:35
int eof_reached
true if eof reached
Definition: avio.h:96
static const uint16_t spdif_mpeg_pkt_offset[2][3]
Definition: spdif.h:54
#define SYNCWORD1
Definition: spdif.h:27
int bit_rate
Total stream bitrate in bit/s, 0 if not available.
Definition: avformat.h:969
AC-3 data.
Definition: spdif.h:32
const char * name
A comma separated list of short names for the format.
Definition: avformat.h:516
This structure stores compressed data.
Definition: avcodec.h:950
Common code between the AC-3 encoder and decoder.
AVInputFormat ff_spdif_demuxer
Definition: spdifdec.c:228