1/* 2 * Maxis XA (.xa) File Demuxer 3 * Copyright (c) 2008 Robert Marston 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/** 23 * @file 24 * Maxis XA File Demuxer 25 * by Robert Marston (rmarston@gmail.com) 26 * for more information on the XA audio format see 27 * http://wiki.multimedia.cx/index.php?title=Maxis_XA 28 */ 29 30#include "libavutil/intreadwrite.h" 31#include "avformat.h" 32#include "internal.h" 33 34#define XA00_TAG MKTAG('X', 'A', 0, 0) 35#define XAI0_TAG MKTAG('X', 'A', 'I', 0) 36#define XAJ0_TAG MKTAG('X', 'A', 'J', 0) 37 38typedef struct MaxisXADemuxContext { 39 uint32_t out_size; 40 uint32_t sent_bytes; 41} MaxisXADemuxContext; 42 43static int xa_probe(AVProbeData *p) 44{ 45 int channels, srate, bits_per_sample; 46 if (p->buf_size < 24) 47 return 0; 48 switch(AV_RL32(p->buf)) { 49 case XA00_TAG: 50 case XAI0_TAG: 51 case XAJ0_TAG: 52 break; 53 default: 54 return 0; 55 } 56 channels = AV_RL16(p->buf + 10); 57 srate = AV_RL32(p->buf + 12); 58 bits_per_sample = AV_RL16(p->buf + 22); 59 if (!channels || channels > 8 || !srate || srate > 192000 || 60 bits_per_sample < 4 || bits_per_sample > 32) 61 return 0; 62 return AVPROBE_SCORE_EXTENSION; 63} 64 65static int xa_read_header(AVFormatContext *s) 66{ 67 MaxisXADemuxContext *xa = s->priv_data; 68 AVIOContext *pb = s->pb; 69 AVStream *st; 70 71 /*Set up the XA Audio Decoder*/ 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 = AV_CODEC_ID_ADPCM_EA_MAXIS_XA; 78 avio_skip(pb, 4); /* Skip the XA ID */ 79 xa->out_size = avio_rl32(pb); 80 avio_skip(pb, 2); /* Skip the tag */ 81 st->codec->channels = avio_rl16(pb); 82 st->codec->sample_rate = avio_rl32(pb); 83 avio_skip(pb, 4); /* Skip average byte rate */ 84 avio_skip(pb, 2); /* Skip block align */ 85 avio_skip(pb, 2); /* Skip bits-per-sample */ 86 87 if (!st->codec->channels || !st->codec->sample_rate) 88 return AVERROR_INVALIDDATA; 89 90 st->codec->bit_rate = av_clip(15LL * st->codec->channels * 8 * 91 st->codec->sample_rate / 28, 0, INT_MAX); 92 93 avpriv_set_pts_info(st, 64, 1, st->codec->sample_rate); 94 st->start_time = 0; 95 96 return 0; 97} 98 99static int xa_read_packet(AVFormatContext *s, 100 AVPacket *pkt) 101{ 102 MaxisXADemuxContext *xa = s->priv_data; 103 AVStream *st = s->streams[0]; 104 AVIOContext *pb = s->pb; 105 unsigned int packet_size; 106 int ret; 107 108 if (xa->sent_bytes >= xa->out_size) 109 return AVERROR_EOF; 110 /* 1 byte header and 14 bytes worth of samples * number channels per block */ 111 packet_size = 15*st->codec->channels; 112 113 ret = av_get_packet(pb, pkt, packet_size); 114 if(ret < 0) 115 return ret; 116 117 pkt->stream_index = st->index; 118 xa->sent_bytes += packet_size; 119 pkt->duration = 28; 120 121 return ret; 122} 123 124AVInputFormat ff_xa_demuxer = { 125 .name = "xa", 126 .long_name = NULL_IF_CONFIG_SMALL("Maxis XA"), 127 .priv_data_size = sizeof(MaxisXADemuxContext), 128 .read_probe = xa_probe, 129 .read_header = xa_read_header, 130 .read_packet = xa_read_packet, 131}; 132