1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
|
/*
* IEC 61937 demuxer
* Copyright (c) 2010 Anssi Hannula <anssi.hannula at iki.fi>
*
* This file is part of Libav.
*
* Libav is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation; either
* version 2.1 of the License, or (at your option) any later version.
*
* Libav is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with Libav; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
*/
/**
* @file
* IEC 61937 demuxer, used for compressed data in S/PDIF
* @author Anssi Hannula
*/
#include "avformat.h"
#include "spdif.h"
#include "libavcodec/ac3.h"
#include "libavcodec/aacadtsdec.h"
static int spdif_get_offset_and_codec(AVFormatContext *s,
enum IEC61937DataType data_type,
const char *buf, int *offset,
enum CodecID *codec)
{
AACADTSHeaderInfo aac_hdr;
GetBitContext gbc;
switch (data_type & 0xff) {
case IEC61937_AC3:
*offset = AC3_FRAME_SIZE << 2;
*codec = CODEC_ID_AC3;
break;
case IEC61937_MPEG1_LAYER1:
*offset = spdif_mpeg_pkt_offset[1][0];
*codec = CODEC_ID_MP1;
break;
case IEC61937_MPEG1_LAYER23:
*offset = spdif_mpeg_pkt_offset[1][0];
*codec = CODEC_ID_MP3;
break;
case IEC61937_MPEG2_EXT:
*offset = 4608;
*codec = CODEC_ID_MP3;
break;
case IEC61937_MPEG2_AAC:
init_get_bits(&gbc, buf, AAC_ADTS_HEADER_SIZE * 8);
if (avpriv_aac_parse_header(&gbc, &aac_hdr)) {
if (s) /* be silent during a probe */
av_log(s, AV_LOG_ERROR, "Invalid AAC packet in IEC 61937\n");
return AVERROR_INVALIDDATA;
}
*offset = aac_hdr.samples << 2;
*codec = CODEC_ID_AAC;
break;
case IEC61937_MPEG2_LAYER1_LSF:
*offset = spdif_mpeg_pkt_offset[0][0];
*codec = CODEC_ID_MP1;
break;
case IEC61937_MPEG2_LAYER2_LSF:
*offset = spdif_mpeg_pkt_offset[0][1];
*codec = CODEC_ID_MP2;
break;
case IEC61937_MPEG2_LAYER3_LSF:
*offset = spdif_mpeg_pkt_offset[0][2];
*codec = CODEC_ID_MP3;
break;
case IEC61937_DTS1:
*offset = 2048;
*codec = CODEC_ID_DTS;
break;
case IEC61937_DTS2:
*offset = 4096;
*codec = CODEC_ID_DTS;
break;
case IEC61937_DTS3:
*offset = 8192;
*codec = CODEC_ID_DTS;
break;
default:
if (s) { /* be silent during a probe */
av_log(s, AV_LOG_WARNING, "Data type 0x%04x", data_type);
av_log_missing_feature(s, " in IEC 61937 is", 1);
}
return AVERROR_PATCHWELCOME;
}
return 0;
}
/* Largest offset between bursts we currently handle, i.e. AAC with
aac_hdr.samples = 4096 */
#define SPDIF_MAX_OFFSET 16384
static int spdif_probe(AVProbeData *p)
{
const uint8_t *buf = p->buf;
const uint8_t *probe_end = p->buf + FFMIN(2 * SPDIF_MAX_OFFSET, p->buf_size - 1);
const uint8_t *expected_code = buf + 7;
uint32_t state = 0;
int sync_codes = 0;
int consecutive_codes = 0;
int offset;
enum CodecID codec;
for (; buf < probe_end; buf++) {
state = (state << 8) | *buf;
if (state == (AV_BSWAP16C(SYNCWORD1) << 16 | AV_BSWAP16C(SYNCWORD2))
&& buf[1] < 0x37) {
sync_codes++;
if (buf == expected_code) {
if (++consecutive_codes >= 2)
return AVPROBE_SCORE_MAX;
} else
consecutive_codes = 0;
if (buf + 4 + AAC_ADTS_HEADER_SIZE > p->buf + p->buf_size)
break;
/* continue probing to find more sync codes */
probe_end = FFMIN(buf + SPDIF_MAX_OFFSET, p->buf + p->buf_size - 1);
/* skip directly to the next sync code */
if (!spdif_get_offset_and_codec(NULL, (buf[2] << 8) | buf[1],
&buf[5], &offset, &codec)) {
if (buf + offset >= p->buf + p->buf_size)
break;
expected_code = buf + offset;
buf = expected_code - 7;
}
}
}
if (!sync_codes)
return 0;
if (sync_codes >= 6)
/* good amount of sync codes but with unexpected offsets */
return AVPROBE_SCORE_MAX / 2;
/* some sync codes were found */
return AVPROBE_SCORE_MAX / 8;
}
static int spdif_read_header(AVFormatContext *s)
{
s->ctx_flags |= AVFMTCTX_NOHEADER;
return 0;
}
static int spdif_read_packet(AVFormatContext *s, AVPacket *pkt)
{
AVIOContext *pb = s->pb;
enum IEC61937DataType data_type;
enum CodecID codec_id;
uint32_t state = 0;
int pkt_size_bits, offset, ret;
while (state != (AV_BSWAP16C(SYNCWORD1) << 16 | AV_BSWAP16C(SYNCWORD2))) {
state = (state << 8) | avio_r8(pb);
if (pb->eof_reached)
return AVERROR_EOF;
}
data_type = avio_rl16(pb);
pkt_size_bits = avio_rl16(pb);
if (pkt_size_bits % 16)
av_log_ask_for_sample(s, "Packet does not end to a 16-bit boundary.");
ret = av_new_packet(pkt, FFALIGN(pkt_size_bits, 16) >> 3);
if (ret)
return ret;
pkt->pos = avio_tell(pb) - BURST_HEADER_SIZE;
if (avio_read(pb, pkt->data, pkt->size) < pkt->size) {
av_free_packet(pkt);
return AVERROR_EOF;
}
ff_spdif_bswap_buf16((uint16_t *)pkt->data, (uint16_t *)pkt->data, pkt->size >> 1);
ret = spdif_get_offset_and_codec(s, data_type, pkt->data,
&offset, &codec_id);
if (ret) {
av_free_packet(pkt);
return ret;
}
/* skip over the padding to the beginning of the next frame */
avio_skip(pb, offset - pkt->size - BURST_HEADER_SIZE);
if (!s->nb_streams) {
/* first packet, create a stream */
AVStream *st = avformat_new_stream(s, NULL);
if (!st) {
av_free_packet(pkt);
return AVERROR(ENOMEM);
}
st->codec->codec_type = AVMEDIA_TYPE_AUDIO;
st->codec->codec_id = codec_id;
} else if (codec_id != s->streams[0]->codec->codec_id) {
av_log_missing_feature(s, "codec change in IEC 61937", 0);
return AVERROR_PATCHWELCOME;
}
if (!s->bit_rate && s->streams[0]->codec->sample_rate)
/* stream bitrate matches 16-bit stereo PCM bitrate for currently
supported codecs */
s->bit_rate = 2 * 16 * s->streams[0]->codec->sample_rate;
return 0;
}
AVInputFormat ff_spdif_demuxer = {
.name = "spdif",
.long_name = NULL_IF_CONFIG_SMALL("IEC 61937 (compressed data in S/PDIF)"),
.read_probe = spdif_probe,
.read_header = spdif_read_header,
.read_packet = spdif_read_packet,
.flags = AVFMT_GENERIC_INDEX,
};
|
