FFmpeg coverage

Directory: ../../../ffmpeg/
File: src/libavformat/spdifdec.c
Date: 2026-04-21 18:58:04
Exec Total Coverage
Lines: 100 138 72.5%
Functions: 6 6 100.0%
Branches: 50 67 74.6%
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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 FFmpeg.
6 *
7 * FFmpeg 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 * FFmpeg 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 FFmpeg; if not, write to the Free Software
19 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
20 */
21
22 /**
23 * @file
24 * IEC 61937 demuxer, used for compressed data in S/PDIF
25 * @author Anssi Hannula
26 */
27
28 #include "libavutil/bswap.h"
29
30 #include "libavcodec/ac3defs.h"
31 #include "libavcodec/adts_parser.h"
32
33 #include "avformat.h"
34 #include "demux.h"
35 #include "internal.h"
36 #include "spdif.h"
37
38 2194 static int spdif_get_offset_and_codec(AVFormatContext *s,
39 enum IEC61937DataType data_type,
40 const char *buf, int *offset,
41 enum AVCodecID *codec)
42 {
43 uint32_t samples;
44 uint8_t frames;
45 int ret;
46
47
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 2194 switch (data_type & 0xff) {
48 107 case IEC61937_AC3:
49 107 *offset = AC3_FRAME_SIZE << 2;
50 107 *codec = AV_CODEC_ID_AC3;
51 107 break;
52 ✗ case IEC61937_MPEG1_LAYER1:
53 ✗ *offset = spdif_mpeg_pkt_offset[1][0];
54 ✗ *codec = AV_CODEC_ID_MP1;
55 ✗ break;
56 114 case IEC61937_MPEG1_LAYER23:
57 114 *offset = spdif_mpeg_pkt_offset[1][0];
58 114 *codec = AV_CODEC_ID_MP3;
59 114 break;
60 ✗ case IEC61937_MPEG2_EXT:
61 ✗ *offset = 4608;
62 ✗ *codec = AV_CODEC_ID_MP3;
63 ✗ break;
64 102 case IEC61937_MPEG2_AAC:
65 102 ret = av_adts_header_parse(buf, &samples, &frames);
66
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 102 if (ret < 0) {
67
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 16 if (s) /* be silent during a probe */
68 ✗ av_log(s, AV_LOG_ERROR, "Invalid AAC packet in IEC 61937\n");
69 16 return ret;
70 }
71 86 *offset = samples << 2;
72 86 *codec = AV_CODEC_ID_AAC;
73 86 break;
74 ✗ case IEC61937_MPEG2_LAYER1_LSF:
75 ✗ *offset = spdif_mpeg_pkt_offset[0][0];
76 ✗ *codec = AV_CODEC_ID_MP1;
77 ✗ break;
78 ✗ case IEC61937_MPEG2_LAYER2_LSF:
79 ✗ *offset = spdif_mpeg_pkt_offset[0][1];
80 ✗ *codec = AV_CODEC_ID_MP2;
81 ✗ break;
82 ✗ case IEC61937_MPEG2_LAYER3_LSF:
83 ✗ *offset = spdif_mpeg_pkt_offset[0][2];
84 ✗ *codec = AV_CODEC_ID_MP3;
85 ✗ break;
86 1189 case IEC61937_DTS1:
87 1189 *offset = 2048;
88 1189 *codec = AV_CODEC_ID_DTS;
89 1189 break;
90 ✗ case IEC61937_DTS2:
91 ✗ *offset = 4096;
92 ✗ *codec = AV_CODEC_ID_DTS;
93 ✗ break;
94 ✗ case IEC61937_DTS3:
95 ✗ *offset = 8192;
96 ✗ *codec = AV_CODEC_ID_DTS;
97 ✗ break;
98 662 case IEC61937_EAC3:
99 662 *offset = 24576;
100 662 *codec = AV_CODEC_ID_EAC3;
101 662 break;
102 20 default:
103
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 20 if (s) { /* be silent during a probe */
104 ✗ avpriv_request_sample(s, "Data type 0x%04x in IEC 61937",
105 data_type);
106 }
107 20 return AVERROR_PATCHWELCOME;
108 }
109 2158 return 0;
110 }
111
112 /* Largest offset between bursts we currently handle, i.e. AAC with
113 samples = 4096 */
114 #define SPDIF_MAX_OFFSET 16384
115
116 7467 static int spdif_probe(const AVProbeData *p)
117 {
118 enum AVCodecID codec;
119 7467 return ff_spdif_probe (p->buf, p->buf_size, &codec);
120 }
121
122 8005 int ff_spdif_probe(const uint8_t *p_buf, int buf_size, enum AVCodecID *codec)
123 {
124 8005 const uint8_t *buf = p_buf;
125
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 8005 const uint8_t *probe_end = p_buf + FFMIN(2 * SPDIF_MAX_OFFSET, buf_size - 1);
126 8005 const uint8_t *expected_code = buf + 7;
127 8005 uint32_t state = 0;
128 8005 int sync_codes = 0;
129 8005 int consecutive_codes = 0;
130 int offset;
131
132
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 105360682 for (; buf < probe_end; buf++) {
133 105352695 state = (state << 8) | *buf;
134
135
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 105352695 if (state == (AV_BSWAP16C(SYNCWORD1) << 16 | AV_BSWAP16C(SYNCWORD2))
136
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 101 && buf[1] < 0x37) {
137 101 sync_codes++;
138
139
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 101 if (buf == expected_code) {
140
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 11 if (++consecutive_codes >= 2)
141 4 return AVPROBE_SCORE_MAX;
142 } else
143 90 consecutive_codes = 0;
144
145
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 97 if (buf + 4 + AV_AAC_ADTS_HEADER_SIZE > p_buf + buf_size)
146 ✗ break;
147
148 /* continue probing to find more sync codes */
149 97 probe_end = FFMIN(buf + SPDIF_MAX_OFFSET, p_buf + buf_size - 1);
150
151 /* skip directly to the next sync code */
152
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 97 if (!spdif_get_offset_and_codec(NULL, (buf[2] << 8) | buf[1],
153 97 &buf[5], &offset, codec)) {
154
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 61 if (buf + offset >= p_buf + buf_size)
155 14 break;
156 47 expected_code = buf + offset;
157 47 buf = expected_code - 7;
158 }
159 }
160 }
161
162
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 8001 if (!sync_codes)
163 7958 return 0;
164
165
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 43 if (sync_codes >= 6)
166 /* good amount of sync codes but with unexpected offsets */
167 3 return AVPROBE_SCORE_EXTENSION;
168
169 /* some sync codes were found */
170 40 return AVPROBE_SCORE_EXTENSION / 4;
171 }
172
173 7 static int spdif_read_header(AVFormatContext *s)
174 {
175 7 s->ctx_flags |= AVFMTCTX_NOHEADER;
176 7 return 0;
177 }
178
179 2097 static int spdif_get_pkt_size_bits(int type, int code)
180 {
181
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 2097 switch (type & 0xff) {
182 652 case IEC61937_EAC3:
183 652 return code << 3;
184 1445 default:
185 1445 return code;
186 }
187 }
188
189 2113 int ff_spdif_read_packet(AVFormatContext *s, AVPacket *pkt)
190 {
191 2113 AVIOContext *pb = s->pb;
192 enum IEC61937DataType data_type;
193 enum AVCodecID codec_id;
194 2113 uint32_t state = 0;
195 int pkt_size_bits, offset, ret;
196
197
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 262405 while (state != (AV_BSWAP16C(SYNCWORD1) << 16 | AV_BSWAP16C(SYNCWORD2))) {
198 260308 state = (state << 8) | avio_r8(pb);
199
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 260308 if (avio_feof(pb))
200 16 return AVERROR_EOF;
201 }
202
203 2097 data_type = avio_rl16(pb);
204 2097 pkt_size_bits = spdif_get_pkt_size_bits(data_type, avio_rl16(pb));
205
206
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 2097 if (pkt_size_bits % 16)
207 ✗ avpriv_request_sample(s, "Packet not ending at a 16-bit boundary");
208
209 2097 ret = av_new_packet(pkt, FFALIGN(pkt_size_bits, 16) >> 3);
210
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 2097 if (ret)
211 ✗ return ret;
212
213 2097 pkt->pos = avio_tell(pb) - BURST_HEADER_SIZE;
214
215
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 2097 if (avio_read(pb, pkt->data, pkt->size) < pkt->size) {
216 ✗ return AVERROR_EOF;
217 }
218 2097 ff_spdif_bswap_buf16((uint16_t *)pkt->data, (uint16_t *)pkt->data, pkt->size >> 1);
219
220 2097 ret = spdif_get_offset_and_codec(s, data_type, pkt->data,
221 &offset, &codec_id);
222
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 2097 if (ret < 0) {
223 ✗ return ret;
224 }
225
226 /* skip over the padding to the beginning of the next frame */
227 2097 avio_skip(pb, offset - pkt->size - BURST_HEADER_SIZE);
228
229
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 2097 if (!s->nb_streams) {
230 /* first packet, create a stream */
231 7 AVStream *st = avformat_new_stream(s, NULL);
232
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 7 if (!st) {
233 ✗ return AVERROR(ENOMEM);
234 }
235 7 st->codecpar->codec_type = AVMEDIA_TYPE_AUDIO;
236 7 st->codecpar->codec_id = codec_id;
237
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 7 if (codec_id == AV_CODEC_ID_EAC3)
238 1 ffstream(st)->need_parsing = AVSTREAM_PARSE_FULL;
239 else
240 6 ffstream(st)->need_parsing = AVSTREAM_PARSE_HEADERS;
241
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 2090 } else if (codec_id != s->streams[0]->codecpar->codec_id) {
242 ✗ avpriv_report_missing_feature(s, "Codec change in IEC 61937");
243 ✗ return AVERROR_PATCHWELCOME;
244 }
245
246
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 2097 if (!s->bit_rate && s->streams[0]->codecpar->sample_rate)
247 /* stream bitrate matches 16-bit stereo PCM bitrate for currently
248 supported codecs */
249 8 s->bit_rate = 2 * 16LL * s->streams[0]->codecpar->sample_rate;
250
251 2097 return 0;
252 }
253
254 const FFInputFormat ff_spdif_demuxer = {
255 .p.name = "spdif",
256 .p.long_name = NULL_IF_CONFIG_SMALL("IEC 61937 (compressed data in S/PDIF)"),
257 .p.flags = AVFMT_GENERIC_INDEX,
258 .read_probe = spdif_probe,
259 .read_header = spdif_read_header,
260 .read_packet = ff_spdif_read_packet,
261 };
262