yading@11: /*
yading@11:  * Maxis XA (.xa) File Demuxer
yading@11:  * Copyright (c) 2008 Robert Marston
yading@11:  *
yading@11:  * This file is part of FFmpeg.
yading@11:  *
yading@11:  * FFmpeg is free software; you can redistribute it and/or
yading@11:  * modify it under the terms of the GNU Lesser General Public
yading@11:  * License as published by the Free Software Foundation; either
yading@11:  * version 2.1 of the License, or (at your option) any later version.
yading@11:  *
yading@11:  * FFmpeg is distributed in the hope that it will be useful,
yading@11:  * but WITHOUT ANY WARRANTY; without even the implied warranty of
yading@11:  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
yading@11:  * Lesser General Public License for more details.
yading@11:  *
yading@11:  * You should have received a copy of the GNU Lesser General Public
yading@11:  * License along with FFmpeg; if not, write to the Free Software
yading@11:  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
yading@11:  */
yading@11: 
yading@11: /**
yading@11:  * @file
yading@11:  * Maxis XA File Demuxer
yading@11:  * by Robert Marston (rmarston@gmail.com)
yading@11:  * for more information on the XA audio format see
yading@11:  *   http://wiki.multimedia.cx/index.php?title=Maxis_XA
yading@11:  */
yading@11: 
yading@11: #include "libavutil/intreadwrite.h"
yading@11: #include "avformat.h"
yading@11: #include "internal.h"
yading@11: 
yading@11: #define XA00_TAG MKTAG('X', 'A', 0, 0)
yading@11: #define XAI0_TAG MKTAG('X', 'A', 'I', 0)
yading@11: #define XAJ0_TAG MKTAG('X', 'A', 'J', 0)
yading@11: 
yading@11: typedef struct MaxisXADemuxContext {
yading@11:     uint32_t out_size;
yading@11:     uint32_t sent_bytes;
yading@11: } MaxisXADemuxContext;
yading@11: 
yading@11: static int xa_probe(AVProbeData *p)
yading@11: {
yading@11:     int channels, srate, bits_per_sample;
yading@11:     if (p->buf_size < 24)
yading@11:         return 0;
yading@11:     switch(AV_RL32(p->buf)) {
yading@11:     case XA00_TAG:
yading@11:     case XAI0_TAG:
yading@11:     case XAJ0_TAG:
yading@11:         break;
yading@11:     default:
yading@11:         return 0;
yading@11:     }
yading@11:     channels        = AV_RL16(p->buf + 10);
yading@11:     srate           = AV_RL32(p->buf + 12);
yading@11:     bits_per_sample = AV_RL16(p->buf + 22);
yading@11:     if (!channels || channels > 8 || !srate || srate > 192000 ||
yading@11:         bits_per_sample < 4 || bits_per_sample > 32)
yading@11:         return 0;
yading@11:     return AVPROBE_SCORE_MAX/2;
yading@11: }
yading@11: 
yading@11: static int xa_read_header(AVFormatContext *s)
yading@11: {
yading@11:     MaxisXADemuxContext *xa = s->priv_data;
yading@11:     AVIOContext *pb = s->pb;
yading@11:     AVStream *st;
yading@11: 
yading@11:     /*Set up the XA Audio Decoder*/
yading@11:     st = avformat_new_stream(s, NULL);
yading@11:     if (!st)
yading@11:         return AVERROR(ENOMEM);
yading@11: 
yading@11:     st->codec->codec_type   = AVMEDIA_TYPE_AUDIO;
yading@11:     st->codec->codec_id     = AV_CODEC_ID_ADPCM_EA_MAXIS_XA;
yading@11:     avio_skip(pb, 4);       /* Skip the XA ID */
yading@11:     xa->out_size            =  avio_rl32(pb);
yading@11:     avio_skip(pb, 2);       /* Skip the tag */
yading@11:     st->codec->channels     = avio_rl16(pb);
yading@11:     st->codec->sample_rate  = avio_rl32(pb);
yading@11:     avio_skip(pb, 4);       /* Skip average byte rate */
yading@11:     avio_skip(pb, 2);       /* Skip block align */
yading@11:     avio_skip(pb, 2);       /* Skip bits-per-sample */
yading@11: 
yading@11:     st->codec->bit_rate = av_clip(15LL * st->codec->channels * 8 *
yading@11:                                   st->codec->sample_rate / 28, 0, INT_MAX);
yading@11: 
yading@11:     avpriv_set_pts_info(st, 64, 1, st->codec->sample_rate);
yading@11:     st->start_time = 0;
yading@11: 
yading@11:     return 0;
yading@11: }
yading@11: 
yading@11: static int xa_read_packet(AVFormatContext *s,
yading@11:                           AVPacket *pkt)
yading@11: {
yading@11:     MaxisXADemuxContext *xa = s->priv_data;
yading@11:     AVStream *st = s->streams[0];
yading@11:     AVIOContext *pb = s->pb;
yading@11:     unsigned int packet_size;
yading@11:     int ret;
yading@11: 
yading@11:     if (xa->sent_bytes >= xa->out_size)
yading@11:         return AVERROR_EOF;
yading@11:     /* 1 byte header and 14 bytes worth of samples * number channels per block */
yading@11:     packet_size = 15*st->codec->channels;
yading@11: 
yading@11:     ret = av_get_packet(pb, pkt, packet_size);
yading@11:     if(ret < 0)
yading@11:         return ret;
yading@11: 
yading@11:     pkt->stream_index = st->index;
yading@11:     xa->sent_bytes += packet_size;
yading@11:     pkt->duration = 28;
yading@11: 
yading@11:     return ret;
yading@11: }
yading@11: 
yading@11: AVInputFormat ff_xa_demuxer = {
yading@11:     .name           = "xa",
yading@11:     .long_name      = NULL_IF_CONFIG_SMALL("Maxis XA"),
yading@11:     .priv_data_size = sizeof(MaxisXADemuxContext),
yading@11:     .read_probe     = xa_probe,
yading@11:     .read_header    = xa_read_header,
yading@11:     .read_packet    = xa_read_packet,
yading@11: };