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