1/*
2 * AST demuxer
3 * Copyright (c) 2012 Paul B Mahol
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/channel_layout.h"
23#include "libavutil/intreadwrite.h"
24#include "avformat.h"
25#include "internal.h"
26#include "ast.h"
27
28static int ast_probe(AVProbeData *p)
29{
30    if (AV_RL32(p->buf) != MKTAG('S','T','R','M'))
31        return 0;
32
33    if (!AV_RB16(p->buf + 10) ||
34        !AV_RB16(p->buf + 12) || AV_RB16(p->buf + 12) > 256 ||
35        !AV_RB32(p->buf + 16) || AV_RB32(p->buf + 16) > 8*48000)
36        return AVPROBE_SCORE_MAX / 8;
37
38    return AVPROBE_SCORE_MAX / 3 * 2;
39}
40
41static int ast_read_header(AVFormatContext *s)
42{
43    int depth;
44    AVStream *st;
45
46    st = avformat_new_stream(s, NULL);
47    if (!st)
48        return AVERROR(ENOMEM);
49
50    avio_skip(s->pb, 8);
51    st->codec->codec_type = AVMEDIA_TYPE_AUDIO;
52    st->codec->codec_id   = ff_codec_get_id(ff_codec_ast_tags, avio_rb16(s->pb));
53
54    depth = avio_rb16(s->pb);
55    if (depth != 16) {
56        avpriv_request_sample(s, "depth %d", depth);
57        return AVERROR_INVALIDDATA;
58    }
59
60    st->codec->channels = avio_rb16(s->pb);
61    if (!st->codec->channels)
62        return AVERROR_INVALIDDATA;
63
64    if (st->codec->channels == 2)
65        st->codec->channel_layout = AV_CH_LAYOUT_STEREO;
66    else if (st->codec->channels == 4)
67        st->codec->channel_layout = AV_CH_LAYOUT_4POINT0;
68
69    avio_skip(s->pb, 2);
70    st->codec->sample_rate = avio_rb32(s->pb);
71    if (st->codec->sample_rate <= 0)
72        return AVERROR_INVALIDDATA;
73    st->start_time         = 0;
74    st->duration           = avio_rb32(s->pb);
75    avio_skip(s->pb, 40);
76    avpriv_set_pts_info(st, 64, 1, st->codec->sample_rate);
77
78    return 0;
79}
80
81static int ast_read_packet(AVFormatContext *s, AVPacket *pkt)
82{
83    uint32_t type, size;
84    int64_t pos;
85    int ret;
86
87    if (url_feof(s->pb))
88        return AVERROR_EOF;
89
90    pos  = avio_tell(s->pb);
91    type = avio_rl32(s->pb);
92    size = avio_rb32(s->pb);
93    if (size > INT_MAX / s->streams[0]->codec->channels)
94        return AVERROR_INVALIDDATA;
95
96    size *= s->streams[0]->codec->channels;
97    if ((ret = avio_skip(s->pb, 24)) < 0) // padding
98        return ret;
99
100    if (type == MKTAG('B','L','C','K')) {
101        ret = av_get_packet(s->pb, pkt, size);
102        pkt->stream_index = 0;
103        pkt->pos = pos;
104    } else {
105        av_log(s, AV_LOG_ERROR, "unknown chunk %x\n", type);
106        avio_skip(s->pb, size);
107        ret = AVERROR_INVALIDDATA;
108    }
109
110    return ret;
111}
112
113AVInputFormat ff_ast_demuxer = {
114    .name           = "ast",
115    .long_name      = NULL_IF_CONFIG_SMALL("AST (Audio Stream)"),
116    .read_probe     = ast_probe,
117    .read_header    = ast_read_header,
118    .read_packet    = ast_read_packet,
119    .extensions     = "ast",
120    .flags          = AVFMT_GENERIC_INDEX,
121    .codec_tag      = (const AVCodecTag* const []){ff_codec_ast_tags, 0},
122};
123