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 33#define XA00_TAG MKTAG('X', 'A', 0, 0) 34#define XAI0_TAG MKTAG('X', 'A', 'I', 0) 35#define XAJ0_TAG MKTAG('X', 'A', 'J', 0) 36 37typedef struct MaxisXADemuxContext { 38 uint32_t out_size; 39 uint32_t sent_bytes; 40 uint32_t audio_frame_counter; 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_MAX/2; 63} 64 65static int xa_read_header(AVFormatContext *s, 66 AVFormatParameters *ap) 67{ 68 MaxisXADemuxContext *xa = s->priv_data; 69 ByteIOContext *pb = s->pb; 70 AVStream *st; 71 72 /*Set up the XA Audio Decoder*/ 73 st = av_new_stream(s, 0); 74 if (!st) 75 return AVERROR(ENOMEM); 76 77 st->codec->codec_type = AVMEDIA_TYPE_AUDIO; 78 st->codec->codec_id = CODEC_ID_ADPCM_EA_MAXIS_XA; 79 url_fskip(pb, 4); /* Skip the XA ID */ 80 xa->out_size = get_le32(pb); 81 url_fskip(pb, 2); /* Skip the tag */ 82 st->codec->channels = get_le16(pb); 83 st->codec->sample_rate = get_le32(pb); 84 /* Value in file is average byte rate*/ 85 st->codec->bit_rate = get_le32(pb) * 8; 86 st->codec->block_align = get_le16(pb); 87 st->codec->bits_per_coded_sample = get_le16(pb); 88 89 av_set_pts_info(st, 64, 1, st->codec->sample_rate); 90 91 return 0; 92} 93 94static int xa_read_packet(AVFormatContext *s, 95 AVPacket *pkt) 96{ 97 MaxisXADemuxContext *xa = s->priv_data; 98 AVStream *st = s->streams[0]; 99 ByteIOContext *pb = s->pb; 100 unsigned int packet_size; 101 int ret; 102 103 if(xa->sent_bytes > xa->out_size) 104 return AVERROR(EIO); 105 /* 1 byte header and 14 bytes worth of samples * number channels per block */ 106 packet_size = 15*st->codec->channels; 107 108 ret = av_get_packet(pb, pkt, packet_size); 109 if(ret < 0) 110 return ret; 111 112 pkt->stream_index = st->index; 113 xa->sent_bytes += packet_size; 114 pkt->pts = xa->audio_frame_counter; 115 /* 14 bytes Samples per channel with 2 samples per byte */ 116 xa->audio_frame_counter += 28 * st->codec->channels; 117 118 return ret; 119} 120 121AVInputFormat xa_demuxer = { 122 "xa", 123 NULL_IF_CONFIG_SMALL("Maxis XA File Format"), 124 sizeof(MaxisXADemuxContext), 125 xa_probe, 126 xa_read_header, 127 xa_read_packet, 128}; 129