1/*
2 * raw ADTS AAC demuxer
3 * Copyright (c) 2008 Michael Niedermayer <michaelni@gmx.at>
4 * Copyright (c) 2009 Robert Swain ( rob opendot cl )
5 *
6 * This file is part of FFmpeg.
7 *
8 * FFmpeg is free software; you can redistribute it and/or
9 * modify it under the terms of the GNU Lesser General Public
10 * License as published by the Free Software Foundation; either
11 * version 2.1 of the License, or (at your option) any later version.
12 *
13 * FFmpeg is distributed in the hope that it will be useful,
14 * but WITHOUT ANY WARRANTY; without even the implied warranty of
15 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
16 * Lesser General Public License for more details.
17 *
18 * You should have received a copy of the GNU Lesser General Public
19 * License along with FFmpeg; if not, write to the Free Software
20 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
21 */
22
23#include "libavutil/intreadwrite.h"
24#include "avformat.h"
25#include "internal.h"
26#include "rawdec.h"
27#include "id3v1.h"
28#include "apetag.h"
29
30static int adts_aac_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 - 7;
38
39    buf = buf0;
40
41    for (; buf < end; buf = buf2 + 1) {
42        buf2 = buf;
43
44        for (frames = 0; buf2 < end; frames++) {
45            uint32_t header = AV_RB16(buf2);
46            if ((header & 0xFFF6) != 0xFFF0) {
47                if (buf != buf0) {
48                    // Found something that isn't an ADTS header, starting
49                    // from a position other than the start of the buffer.
50                    // Discard the count we've accumulated so far since it
51                    // probably was a false positive.
52                    frames = 0;
53                }
54                break;
55            }
56            fsize = (AV_RB32(buf2 + 3) >> 13) & 0x1FFF;
57            if (fsize < 7)
58                break;
59            fsize = FFMIN(fsize, end - buf2);
60            buf2 += fsize;
61        }
62        max_frames = FFMAX(max_frames, frames);
63        if (buf == buf0)
64            first_frames = frames;
65    }
66
67    if (first_frames >= 3)
68        return AVPROBE_SCORE_EXTENSION + 1;
69    else if (max_frames > 100)
70        return AVPROBE_SCORE_EXTENSION;
71    else if (max_frames >= 3)
72        return AVPROBE_SCORE_EXTENSION / 2;
73    else if (max_frames >= 1)
74        return 1;
75    else
76        return 0;
77}
78
79static int adts_aac_read_header(AVFormatContext *s)
80{
81    AVStream *st;
82
83    st = avformat_new_stream(s, NULL);
84    if (!st)
85        return AVERROR(ENOMEM);
86
87    st->codec->codec_type = AVMEDIA_TYPE_AUDIO;
88    st->codec->codec_id   = s->iformat->raw_codec_id;
89    st->need_parsing      = AVSTREAM_PARSE_FULL_RAW;
90
91    ff_id3v1_read(s);
92    if (s->pb->seekable &&
93        !av_dict_get(s->metadata, "", NULL, AV_DICT_IGNORE_SUFFIX)) {
94        int64_t cur = avio_tell(s->pb);
95        ff_ape_parse_tag(s);
96        avio_seek(s->pb, cur, SEEK_SET);
97    }
98
99    // LCM of all possible ADTS sample rates
100    avpriv_set_pts_info(st, 64, 1, 28224000);
101
102    return 0;
103}
104
105AVInputFormat ff_aac_demuxer = {
106    .name         = "aac",
107    .long_name    = NULL_IF_CONFIG_SMALL("raw ADTS AAC (Advanced Audio Coding)"),
108    .read_probe   = adts_aac_probe,
109    .read_header  = adts_aac_read_header,
110    .read_packet  = ff_raw_read_partial_packet,
111    .flags        = AVFMT_GENERIC_INDEX,
112    .extensions   = "aac",
113    .raw_codec_id = AV_CODEC_ID_AAC,
114};
115