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
30static 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
68static 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
86AVInputFormat 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};
95