1 /*
2 * RAW AC-3 and E-AC-3 demuxer
3 * Copyright (c) 2007 Justin Ruggles <justin.ruggles@gmail.com>
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 #include "libavutil/crc.h"
23 #include "libavcodec/ac3_parser.h"
24 #include "avformat.h"
25 #include "rawdec.h"
26
ac3_eac3_probe(AVProbeData * p,enum AVCodecID expected_codec_id)27 static int ac3_eac3_probe(AVProbeData *p, enum AVCodecID expected_codec_id)
28 {
29 int max_frames, first_frames = 0, frames;
30 const uint8_t *buf, *buf2, *end;
31 AC3HeaderInfo *phdr = NULL;
32 GetBitContext gbc;
33 enum AVCodecID codec_id = AV_CODEC_ID_AC3;
34
35 max_frames = 0;
36 buf = p->buf;
37 end = buf + p->buf_size;
38
39 for(; buf < end; buf++) {
40 if(buf > p->buf && !(buf[0] == 0x0B && buf[1] == 0x77)
41 && !(buf[0] == 0x77 && buf[1] == 0x0B) )
42 continue;
43 buf2 = buf;
44
45 for(frames = 0; buf2 < end; frames++) {
46 uint8_t buf3[4096];
47 int i;
48 if(!memcmp(buf2, "\x1\x10\0\0\0\0\0\0", 8))
49 buf2+=16;
50 if (buf[0] == 0x77 && buf[1] == 0x0B) {
51 for(i=0; i<8; i+=2) {
52 buf3[i ] = buf[i+1];
53 buf3[i+1] = buf[i ];
54 }
55 init_get_bits(&gbc, buf3, 54);
56 }else
57 init_get_bits(&gbc, buf2, 54);
58 if(avpriv_ac3_parse_header2(&gbc, &phdr) < 0)
59 break;
60 if(buf2 + phdr->frame_size > end)
61 break;
62 if (buf[0] == 0x77 && buf[1] == 0x0B) {
63 av_assert0(phdr->frame_size <= sizeof(buf3));
64 for(i=8; i<phdr->frame_size; i+=2) {
65 buf3[i ] = buf[i+1];
66 buf3[i+1] = buf[i ];
67 }
68 }
69 if(av_crc(av_crc_get_table(AV_CRC_16_ANSI), 0, gbc.buffer + 2, phdr->frame_size - 2))
70 break;
71 if (phdr->bitstream_id > 10)
72 codec_id = AV_CODEC_ID_EAC3;
73 buf2 += phdr->frame_size;
74 }
75 max_frames = FFMAX(max_frames, frames);
76 if(buf == p->buf)
77 first_frames = frames;
78 }
79 av_freep(&phdr);
80 if(codec_id != expected_codec_id) return 0;
81 // keep this in sync with mp3 probe, both need to avoid
82 // issues with MPEG-files!
83 if (first_frames>=4) return AVPROBE_SCORE_EXTENSION + 1;
84 else if(max_frames>200)return AVPROBE_SCORE_EXTENSION;
85 else if(max_frames>=4) return AVPROBE_SCORE_EXTENSION/2;
86 else if(max_frames>=1) return 1;
87 else return 0;
88 }
89
90 #if CONFIG_AC3_DEMUXER
ac3_probe(AVProbeData * p)91 static int ac3_probe(AVProbeData *p)
92 {
93 return ac3_eac3_probe(p, AV_CODEC_ID_AC3);
94 }
95
96 AVInputFormat ff_ac3_demuxer = {
97 .name = "ac3",
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,
103 .extensions = "ac3",
104 .raw_codec_id = AV_CODEC_ID_AC3,
105 };
106 #endif
107
108 #if CONFIG_EAC3_DEMUXER
eac3_probe(AVProbeData * p)109 static int eac3_probe(AVProbeData *p)
110 {
111 return ac3_eac3_probe(p, AV_CODEC_ID_EAC3);
112 }
113
114 AVInputFormat ff_eac3_demuxer = {
115 .name = "eac3",
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,
123 };
124 #endif
125