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1 | /* |
2 | * LOAS AudioSyncStream demuxer | |
3 | * Copyright (c) 2008 Michael Niedermayer <michaelni@gmx.at> | |
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/intreadwrite.h" | |
23 | #include "libavutil/internal.h" | |
24 | #include "avformat.h" | |
25 | #include "internal.h" | |
26 | #include "rawdec.h" | |
27 | ||
28 | #define LOAS_SYNC_WORD 0x2b7 | |
29 | ||
30 | static int loas_probe(AVProbeData *p) | |
31 | { | |
32 | int max_frames = 0, first_frames = 0; | |
33 | int fsize, frames; | |
34 | const uint8_t *buf0 = p->buf; | |
35 | const uint8_t *buf2; | |
36 | const uint8_t *buf; | |
37 | const uint8_t *end = buf0 + p->buf_size - 3; | |
38 | buf = buf0; | |
39 | ||
40 | for (; buf < end; buf = buf2 + 1) { | |
41 | buf2 = buf; | |
42 | ||
43 | for (frames = 0; buf2 < end; frames++) { | |
44 | uint32_t header = AV_RB24(buf2); | |
45 | if ((header >> 13) != LOAS_SYNC_WORD) | |
46 | break; | |
47 | fsize = (header & 0x1FFF) + 3; | |
48 | if (fsize < 7) | |
49 | break; | |
50 | fsize = FFMIN(fsize, end - buf2); | |
51 | buf2 += fsize; | |
52 | } | |
53 | max_frames = FFMAX(max_frames, frames); | |
54 | if (buf == buf0) | |
55 | first_frames = frames; | |
56 | } | |
57 | ||
58 | if (first_frames >= 3) | |
59 | return AVPROBE_SCORE_EXTENSION + 1; | |
60 | else if (max_frames > 100) | |
61 | return AVPROBE_SCORE_EXTENSION; | |
62 | else if (max_frames >= 3) | |
63 | return AVPROBE_SCORE_EXTENSION / 2; | |
64 | else | |
65 | return 0; | |
66 | } | |
67 | ||
68 | static int loas_read_header(AVFormatContext *s) | |
69 | { | |
70 | AVStream *st; | |
71 | ||
72 | st = avformat_new_stream(s, NULL); | |
73 | if (!st) | |
74 | return AVERROR(ENOMEM); | |
75 | ||
76 | st->codec->codec_type = AVMEDIA_TYPE_AUDIO; | |
77 | st->codec->codec_id = s->iformat->raw_codec_id; | |
78 | st->need_parsing = AVSTREAM_PARSE_FULL_RAW; | |
79 | ||
80 | //LCM of all possible AAC sample rates | |
81 | avpriv_set_pts_info(st, 64, 1, 28224000); | |
82 | ||
83 | return 0; | |
84 | } | |
85 | ||
86 | AVInputFormat ff_loas_demuxer = { | |
87 | .name = "loas", | |
88 | .long_name = NULL_IF_CONFIG_SMALL("LOAS AudioSyncStream"), | |
89 | .read_probe = loas_probe, | |
90 | .read_header = loas_read_header, | |
91 | .read_packet = ff_raw_read_partial_packet, | |
92 | .flags= AVFMT_GENERIC_INDEX, | |
93 | .raw_codec_id = AV_CODEC_ID_AAC_LATM, | |
94 | }; |