libavformat/astdec.c

   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 "demux.h"
  26 #include "internal.h"
  27 #include "ast.h"
  28
  29 static int ast_probe(const AVProbeData *p)
  30 {
  31     if (AV_RL32(p->buf) != MKTAG('S','T','R','M'))
  32         return 0;
  33
  34     if (!AV_RB16(p->buf + 10) ||
  35         !AV_RB16(p->buf + 12) || AV_RB16(p->buf + 12) > 256 ||
  36         !AV_RB32(p->buf + 16) || AV_RB32(p->buf + 16) > 8*48000)
  37         return AVPROBE_SCORE_MAX / 8;
  38
  39     return AVPROBE_SCORE_MAX / 3 * 2;
  40 }
  41
  42 static int ast_read_header(AVFormatContext *s)
  43 {
  44     int depth;
  45     AVStream *st;
  46
  47     st = avformat_new_stream(s, NULL);
  48     if (!st)
  49         return AVERROR(ENOMEM);
  50
  51     avio_skip(s->pb, 8);
  52     st->codecpar->codec_type = AVMEDIA_TYPE_AUDIO;
  53     st->codecpar->codec_id   = ff_codec_get_id(ff_codec_ast_tags, avio_rb16(s->pb));
  54
  55     depth = avio_rb16(s->pb);
  56     if (depth != 16) {
  57         avpriv_request_sample(s, "depth %d", depth);
  58         return AVERROR_INVALIDDATA;
  59     }
  60
  61     st->codecpar->ch_layout.nb_channels = avio_rb16(s->pb);
  62     if (!st->codecpar->ch_layout.nb_channels)
  63         return AVERROR_INVALIDDATA;
  64
  65     if (st->codecpar->ch_layout.nb_channels == 2)
  66         st->codecpar->ch_layout = (AVChannelLayout)AV_CHANNEL_LAYOUT_STEREO;
  67     else if (st->codecpar->ch_layout.nb_channels == 4)
  68         st->codecpar->ch_layout = (AVChannelLayout)AV_CHANNEL_LAYOUT_4POINT0;
  69
  70     avio_skip(s->pb, 2);
  71     st->codecpar->sample_rate = avio_rb32(s->pb);
  72     if (st->codecpar->sample_rate <= 0)
  73         return AVERROR_INVALIDDATA;
  74     st->start_time         = 0;
  75     st->duration           = avio_rb32(s->pb);
  76     avio_skip(s->pb, 40);
  77     avpriv_set_pts_info(st, 64, 1, st->codecpar->sample_rate);
  78
  79     return 0;
  80 }
  81
  82 static int ast_read_packet(AVFormatContext *s, AVPacket *pkt)
  83 {
  84     uint32_t type, size;
  85     int64_t pos;
  86     int ret;
  87
  88     if (avio_feof(s->pb))
  89         return AVERROR_EOF;
  90
  91     pos  = avio_tell(s->pb);
  92     type = avio_rl32(s->pb);
  93     size = avio_rb32(s->pb);
  94     if (!s->streams[0]->codecpar->ch_layout.nb_channels ||
  95         size > INT_MAX / s->streams[0]->codecpar->ch_layout.nb_channels)
  96         return AVERROR_INVALIDDATA;
  97
  98     size *= s->streams[0]->codecpar->ch_layout.nb_channels;
  99     if ((ret = avio_skip(s->pb, 24)) < 0) // padding
 100         return ret;
 101
 102     if (type == MKTAG('B','L','C','K')) {
 103         ret = av_get_packet(s->pb, pkt, size);
 104         pkt->stream_index = 0;
 105         pkt->pos = pos;
 106     } else {
 107         av_log(s, AV_LOG_ERROR, "unknown chunk %"PRIx32"\n", type);
 108         avio_skip(s->pb, size);
 109         ret = AVERROR_INVALIDDATA;
 110     }
 111
 112     return ret;
 113 }
 114
 115 const FFInputFormat ff_ast_demuxer = {
 116     .p.name         = "ast",
 117     .p.long_name    = NULL_IF_CONFIG_SMALL("AST (Audio Stream)"),
 118     .p.extensions   = "ast",
 119     .p.flags        = AVFMT_GENERIC_INDEX,
 120     .p.codec_tag    = ff_ast_codec_tags_list,
 121     .read_probe     = ast_probe,
 122     .read_header    = ast_read_header,
 123     .read_packet    = ast_read_packet,
 124 };