3 * Copyright (c) 2010 Anssi Hannula <anssi.hannula at iki.fi>
5 * This file is part of FFmpeg.
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.
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.
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
24 * IEC 61937 demuxer, used for compressed data in S/PDIF
25 * @author Anssi Hannula
28 #include "libavutil/bswap.h"
30 #include "libavcodec/ac3defs.h"
31 #include "libavcodec/adts_parser.h"
37 static int spdif_get_offset_and_codec(AVFormatContext *s,
38 enum IEC61937DataType data_type,
39 const char *buf, int *offset,
40 enum AVCodecID *codec)
46 switch (data_type & 0xff) {
48 *offset = AC3_FRAME_SIZE << 2;
49 *codec = AV_CODEC_ID_AC3;
51 case IEC61937_MPEG1_LAYER1:
52 *offset = spdif_mpeg_pkt_offset[1][0];
53 *codec = AV_CODEC_ID_MP1;
55 case IEC61937_MPEG1_LAYER23:
56 *offset = spdif_mpeg_pkt_offset[1][0];
57 *codec = AV_CODEC_ID_MP3;
59 case IEC61937_MPEG2_EXT:
61 *codec = AV_CODEC_ID_MP3;
63 case IEC61937_MPEG2_AAC:
64 ret = av_adts_header_parse(buf, &samples, &frames);
66 if (s) /* be silent during a probe */
67 av_log(s, AV_LOG_ERROR, "Invalid AAC packet in IEC 61937\n");
70 *offset = samples << 2;
71 *codec = AV_CODEC_ID_AAC;
73 case IEC61937_MPEG2_LAYER1_LSF:
74 *offset = spdif_mpeg_pkt_offset[0][0];
75 *codec = AV_CODEC_ID_MP1;
77 case IEC61937_MPEG2_LAYER2_LSF:
78 *offset = spdif_mpeg_pkt_offset[0][1];
79 *codec = AV_CODEC_ID_MP2;
81 case IEC61937_MPEG2_LAYER3_LSF:
82 *offset = spdif_mpeg_pkt_offset[0][2];
83 *codec = AV_CODEC_ID_MP3;
87 *codec = AV_CODEC_ID_DTS;
91 *codec = AV_CODEC_ID_DTS;
95 *codec = AV_CODEC_ID_DTS;
99 *codec = AV_CODEC_ID_EAC3;
102 if (s) { /* be silent during a probe */
103 avpriv_request_sample(s, "Data type 0x%04x in IEC 61937",
106 return AVERROR_PATCHWELCOME;
111 /* Largest offset between bursts we currently handle, i.e. AAC with
113 #define SPDIF_MAX_OFFSET 16384
115 static int spdif_probe(const AVProbeData *p)
117 enum AVCodecID codec;
118 return ff_spdif_probe (p->buf, p->buf_size, &codec);
121 int ff_spdif_probe(const uint8_t *p_buf, int buf_size, enum AVCodecID *codec)
123 const uint8_t *buf = p_buf;
124 const uint8_t *probe_end = p_buf + FFMIN(2 * SPDIF_MAX_OFFSET, buf_size - 1);
125 const uint8_t *expected_code = buf + 7;
128 int consecutive_codes = 0;
131 for (; buf < probe_end; buf++) {
132 state = (state << 8) | *buf;
134 if (state == (AV_BSWAP16C(SYNCWORD1) << 16 | AV_BSWAP16C(SYNCWORD2))
138 if (buf == expected_code) {
139 if (++consecutive_codes >= 2)
140 return AVPROBE_SCORE_MAX;
142 consecutive_codes = 0;
144 if (buf + 4 + AV_AAC_ADTS_HEADER_SIZE > p_buf + buf_size)
147 /* continue probing to find more sync codes */
148 probe_end = FFMIN(buf + SPDIF_MAX_OFFSET, p_buf + buf_size - 1);
150 /* skip directly to the next sync code */
151 if (!spdif_get_offset_and_codec(NULL, (buf[2] << 8) | buf[1],
152 &buf[5], &offset, codec)) {
153 if (buf + offset >= p_buf + buf_size)
155 expected_code = buf + offset;
156 buf = expected_code - 7;
165 /* good amount of sync codes but with unexpected offsets */
166 return AVPROBE_SCORE_EXTENSION;
168 /* some sync codes were found */
169 return AVPROBE_SCORE_EXTENSION / 4;
172 static int spdif_read_header(AVFormatContext *s)
174 s->ctx_flags |= AVFMTCTX_NOHEADER;
178 static int spdif_get_pkt_size_bits(int type, int code)
180 switch (type & 0xff) {
188 int ff_spdif_read_packet(AVFormatContext *s, AVPacket *pkt)
190 AVIOContext *pb = s->pb;
191 enum IEC61937DataType data_type;
192 enum AVCodecID codec_id;
194 int pkt_size_bits, offset, ret;
196 while (state != (AV_BSWAP16C(SYNCWORD1) << 16 | AV_BSWAP16C(SYNCWORD2))) {
197 state = (state << 8) | avio_r8(pb);
202 data_type = avio_rl16(pb);
203 pkt_size_bits = spdif_get_pkt_size_bits(data_type, avio_rl16(pb));
205 if (pkt_size_bits % 16)
206 avpriv_request_sample(s, "Packet not ending at a 16-bit boundary");
208 ret = av_new_packet(pkt, FFALIGN(pkt_size_bits, 16) >> 3);
212 pkt->pos = avio_tell(pb) - BURST_HEADER_SIZE;
214 if (avio_read(pb, pkt->data, pkt->size) < pkt->size) {
217 ff_spdif_bswap_buf16((uint16_t *)pkt->data, (uint16_t *)pkt->data, pkt->size >> 1);
219 ret = spdif_get_offset_and_codec(s, data_type, pkt->data,
225 /* skip over the padding to the beginning of the next frame */
226 avio_skip(pb, offset - pkt->size - BURST_HEADER_SIZE);
228 if (!s->nb_streams) {
229 /* first packet, create a stream */
230 AVStream *st = avformat_new_stream(s, NULL);
232 return AVERROR(ENOMEM);
234 st->codecpar->codec_type = AVMEDIA_TYPE_AUDIO;
235 st->codecpar->codec_id = codec_id;
236 if (codec_id == AV_CODEC_ID_EAC3)
237 ffstream(st)->need_parsing = AVSTREAM_PARSE_FULL;
238 } else if (codec_id != s->streams[0]->codecpar->codec_id) {
239 avpriv_report_missing_feature(s, "Codec change in IEC 61937");
240 return AVERROR_PATCHWELCOME;
243 if (!s->bit_rate && s->streams[0]->codecpar->sample_rate)
244 /* stream bitrate matches 16-bit stereo PCM bitrate for currently
246 s->bit_rate = 2 * 16LL * s->streams[0]->codecpar->sample_rate;
251 const AVInputFormat ff_spdif_demuxer = {
253 .long_name = NULL_IF_CONFIG_SMALL("IEC 61937 (compressed data in S/PDIF)"),
254 .read_probe = spdif_probe,
255 .read_header = spdif_read_header,
256 .read_packet = ff_spdif_read_packet,
257 .flags = AVFMT_GENERIC_INDEX,