2 * RAW AC-3 and E-AC-3 demuxer
3 * Copyright (c) 2007 Justin Ruggles <justin.ruggles@gmail.com>
5 * This file is part of Libav.
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.
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.
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
22 #include "libavutil/crc.h"
23 #include "libavcodec/ac3_parser.h"
27 static int ac3_eac3_probe(AVProbeData *p, enum AVCodecID expected_codec_id)
29 int max_frames, first_frames = 0, frames;
30 uint8_t *buf, *buf2, *end;
31 enum AVCodecID codec_id = AV_CODEC_ID_AC3;
35 end = buf + p->buf_size;
37 for(; buf < end; buf++) {
40 for(frames = 0; buf2 < end; frames++) {
45 ret = av_ac3_parse_header(buf2, end - buf2, &bitstream_id,
49 if (buf2 + frame_size > end ||
50 av_crc(av_crc_get_table(AV_CRC_16_ANSI), 0, buf2 + 2, frame_size - 2))
52 if (bitstream_id > 10)
53 codec_id = AV_CODEC_ID_EAC3;
56 max_frames = FFMAX(max_frames, frames);
58 first_frames = frames;
60 if(codec_id != expected_codec_id) return 0;
61 // keep this in sync with mp3 probe, both need to avoid
62 // issues with MPEG-files!
63 if (first_frames >= 4) return AVPROBE_SCORE_EXTENSION + 1;
67 unsigned int code = -1;
69 #define VIDEO_ID 0x000001e0
70 #define AUDIO_ID 0x000001c0
71 /* do a search for mpegps headers to be able to properly bias
72 * towards mpegps if we detect this stream as both. */
73 for (i = 0; i<p->buf_size; i++) {
74 code = (code << 8) + p->buf[i];
75 if ((code & 0xffffff00) == 0x100) {
76 if ((code & 0x1f0) == VIDEO_ID) pes++;
77 else if((code & 0x1e0) == AUDIO_ID) pes++;
82 max_frames = (max_frames + pes - 1) / pes;
84 if (max_frames > 500) return AVPROBE_SCORE_EXTENSION;
85 else if (max_frames >= 4) return AVPROBE_SCORE_EXTENSION / 2;
86 else if (max_frames >= 1) return 1;
90 #if CONFIG_AC3_DEMUXER
91 static int ac3_probe(AVProbeData *p)
93 return ac3_eac3_probe(p, AV_CODEC_ID_AC3);
96 AVInputFormat ff_ac3_demuxer = {
98 .long_name = NULL_IF_CONFIG_SMALL("raw AC-3"),
99 .read_probe = ac3_probe,
100 .read_header = ff_raw_audio_read_header,
101 .read_packet = ff_raw_read_partial_packet,
102 .flags= AVFMT_GENERIC_INDEX,
104 .raw_codec_id = AV_CODEC_ID_AC3,
108 #if CONFIG_EAC3_DEMUXER
109 static int eac3_probe(AVProbeData *p)
111 return ac3_eac3_probe(p, AV_CODEC_ID_EAC3);
114 AVInputFormat ff_eac3_demuxer = {
116 .long_name = NULL_IF_CONFIG_SMALL("raw E-AC-3"),
117 .read_probe = eac3_probe,
118 .read_header = ff_raw_audio_read_header,
119 .read_packet = ff_raw_read_partial_packet,
120 .flags = AVFMT_GENERIC_INDEX,
121 .extensions = "eac3",
122 .raw_codec_id = AV_CODEC_ID_EAC3,