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 libavformat/xa.c 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 switch(AV_RL32(p->buf)) { 46 case XA00_TAG: 47 case XAI0_TAG: 48 case XAJ0_TAG: 49 return AVPROBE_SCORE_MAX; 50 } 51 return 0; 52} 53 54static int xa_read_header(AVFormatContext *s, 55 AVFormatParameters *ap) 56{ 57 MaxisXADemuxContext *xa = s->priv_data; 58 ByteIOContext *pb = s->pb; 59 AVStream *st; 60 61 /*Set up the XA Audio Decoder*/ 62 st = av_new_stream(s, 0); 63 if (!st) 64 return AVERROR(ENOMEM); 65 66 st->codec->codec_type = CODEC_TYPE_AUDIO; 67 st->codec->codec_id = CODEC_ID_ADPCM_EA_MAXIS_XA; 68 url_fskip(pb, 4); /* Skip the XA ID */ 69 xa->out_size = get_le32(pb); 70 url_fskip(pb, 2); /* Skip the tag */ 71 st->codec->channels = get_le16(pb); 72 st->codec->sample_rate = get_le32(pb); 73 /* Value in file is average byte rate*/ 74 st->codec->bit_rate = get_le32(pb) * 8; 75 st->codec->block_align = get_le16(pb); 76 st->codec->bits_per_coded_sample = get_le16(pb); 77 78 av_set_pts_info(st, 64, 1, st->codec->sample_rate); 79 80 return 0; 81} 82 83static int xa_read_packet(AVFormatContext *s, 84 AVPacket *pkt) 85{ 86 MaxisXADemuxContext *xa = s->priv_data; 87 AVStream *st = s->streams[0]; 88 ByteIOContext *pb = s->pb; 89 unsigned int packet_size; 90 int ret; 91 92 if(xa->sent_bytes > xa->out_size) 93 return AVERROR(EIO); 94 /* 1 byte header and 14 bytes worth of samples * number channels per block */ 95 packet_size = 15*st->codec->channels; 96 97 ret = av_get_packet(pb, pkt, packet_size); 98 if(ret != packet_size) 99 return AVERROR(EIO); 100 101 pkt->stream_index = st->index; 102 xa->sent_bytes += packet_size; 103 pkt->pts = xa->audio_frame_counter; 104 /* 14 bytes Samples per channel with 2 samples per byte */ 105 xa->audio_frame_counter += 28 * st->codec->channels; 106 107 return ret; 108} 109 110AVInputFormat xa_demuxer = { 111 "xa", 112 NULL_IF_CONFIG_SMALL("Maxis XA File Format"), 113 sizeof(MaxisXADemuxContext), 114 xa_probe, 115 xa_read_header, 116 xa_read_packet, 117}; 118