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/avassert.h"
23 #include "libavutil/crc.h"
24 #include "libavcodec/ac3_parser.h"
25 #include "avformat.h"
26 #include "rawdec.h"
27
ac3_eac3_probe(const AVProbeData * p,enum AVCodecID expected_codec_id)28 static int ac3_eac3_probe(const AVProbeData *p, enum AVCodecID expected_codec_id)
29 {
30 int max_frames, first_frames = 0, frames;
31 const uint8_t *buf, *buf2, *end;
32 enum AVCodecID codec_id = AV_CODEC_ID_AC3;
33
34 max_frames = 0;
35 buf = p->buf;
36 end = buf + p->buf_size;
37
38 for(; buf < end; buf++) {
39 if(buf > p->buf && !(buf[0] == 0x0B && buf[1] == 0x77)
40 && !(buf[0] == 0x77 && buf[1] == 0x0B) )
41 continue;
42 buf2 = buf;
43
44 for(frames = 0; buf2 < end; frames++) {
45 uint8_t buf3[4096];
46 uint8_t bitstream_id;
47 uint16_t frame_size;
48 int i, ret;
49
50 if(!memcmp(buf2, "\x1\x10", 2)) {
51 if (buf2 + 16 > end)
52 break;
53 buf2+=16;
54 }
55 if (buf[0] == 0x77 && buf[1] == 0x0B) {
56 for(i=0; i<8; i+=2) {
57 buf3[i ] = buf2[i+1];
58 buf3[i+1] = buf2[i ];
59 }
60 ret = av_ac3_parse_header(buf3, 8, &bitstream_id,
61 &frame_size);
62 }else
63 ret = av_ac3_parse_header(buf2, end - buf2, &bitstream_id,
64 &frame_size);
65 if (ret < 0)
66 break;
67 if(buf2 + frame_size > end)
68 break;
69 if (buf[0] == 0x77 && buf[1] == 0x0B) {
70 av_assert0(frame_size <= sizeof(buf3));
71 for(i = 8; i < frame_size; i += 2) {
72 buf3[i ] = buf2[i+1];
73 buf3[i+1] = buf2[i ];
74 }
75 if (av_crc(av_crc_get_table(AV_CRC_16_ANSI), 0, buf3 + 2, frame_size - 2))
76 break;
77 } else {
78 if (av_crc(av_crc_get_table(AV_CRC_16_ANSI), 0, buf2 + 2, frame_size - 2))
79 break;
80 }
81 if (bitstream_id > 10)
82 codec_id = AV_CODEC_ID_EAC3;
83 buf2 += frame_size;
84 }
85 max_frames = FFMAX(max_frames, frames);
86 if(buf == p->buf)
87 first_frames = frames;
88 }
89 if(codec_id != expected_codec_id) return 0;
90 // keep this in sync with mp3 probe, both need to avoid
91 // issues with MPEG-files!
92 if (first_frames>=7) return AVPROBE_SCORE_EXTENSION + 1;
93 else if(max_frames>200)return AVPROBE_SCORE_EXTENSION;
94 else if(max_frames>=4) return AVPROBE_SCORE_EXTENSION/2;
95 else if(max_frames>=1) return 1;
96 else return 0;
97 }
98
99 #if CONFIG_AC3_DEMUXER
ac3_probe(const AVProbeData * p)100 static int ac3_probe(const AVProbeData *p)
101 {
102 return ac3_eac3_probe(p, AV_CODEC_ID_AC3);
103 }
104
105 FF_RAW_DEMUXER_CLASS(ac3)
106 AVInputFormat ff_ac3_demuxer = {
107 .name = "ac3",
108 .long_name = NULL_IF_CONFIG_SMALL("raw AC-3"),
109 .read_probe = ac3_probe,
110 .read_header = ff_raw_audio_read_header,
111 .read_packet = ff_raw_read_partial_packet,
112 .flags= AVFMT_GENERIC_INDEX,
113 .extensions = "ac3",
114 .raw_codec_id = AV_CODEC_ID_AC3,
115 .priv_data_size = sizeof(FFRawDemuxerContext),
116 .priv_class = &ac3_demuxer_class,
117 };
118 #endif
119
120 #if CONFIG_EAC3_DEMUXER
eac3_probe(const AVProbeData * p)121 static int eac3_probe(const AVProbeData *p)
122 {
123 return ac3_eac3_probe(p, AV_CODEC_ID_EAC3);
124 }
125
126 FF_RAW_DEMUXER_CLASS(eac3)
127 AVInputFormat ff_eac3_demuxer = {
128 .name = "eac3",
129 .long_name = NULL_IF_CONFIG_SMALL("raw E-AC-3"),
130 .read_probe = eac3_probe,
131 .read_header = ff_raw_audio_read_header,
132 .read_packet = ff_raw_read_partial_packet,
133 .flags = AVFMT_GENERIC_INDEX,
134 .extensions = "eac3",
135 .raw_codec_id = AV_CODEC_ID_EAC3,
136 .priv_data_size = sizeof(FFRawDemuxerContext),
137 .priv_class = &eac3_demuxer_class,
138 };
139 #endif
140