libavformat/xa.c

   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 "demux.h"
  33 #include "internal.h"
  34
  35 #define XA00_TAG MKTAG('X', 'A', 0, 0)
  36 #define XAI0_TAG MKTAG('X', 'A', 'I', 0)
  37 #define XAJ0_TAG MKTAG('X', 'A', 'J', 0)
  38
  39 typedef struct MaxisXADemuxContext {
  40     uint32_t out_size;
  41     uint32_t sent_bytes;
  42 } MaxisXADemuxContext;
  43
  44 static int xa_probe(const AVProbeData *p)
  45 {
  46     int channels, srate, bits_per_sample;
  47     if (p->buf_size < 24)
  48         return 0;
  49     switch(AV_RL32(p->buf)) {
  50     case XA00_TAG:
  51     case XAI0_TAG:
  52     case XAJ0_TAG:
  53         break;
  54     default:
  55         return 0;
  56     }
  57     channels        = AV_RL16(p->buf + 10);
  58     srate           = AV_RL32(p->buf + 12);
  59     bits_per_sample = AV_RL16(p->buf + 22);
  60     if (!channels || channels > 8 || !srate || srate > 192000 ||
  61         bits_per_sample < 4 || bits_per_sample > 32)
  62         return 0;
  63     return AVPROBE_SCORE_EXTENSION;
  64 }
  65
  66 static int xa_read_header(AVFormatContext *s)
  67 {
  68     MaxisXADemuxContext *xa = s->priv_data;
  69     AVIOContext *pb = s->pb;
  70     AVStream *st;
  71
  72     /*Set up the XA Audio Decoder*/
  73     st = avformat_new_stream(s, NULL);
  74     if (!st)
  75         return AVERROR(ENOMEM);
  76
  77     st->codecpar->codec_type   = AVMEDIA_TYPE_AUDIO;
  78     st->codecpar->codec_id     = AV_CODEC_ID_ADPCM_EA_MAXIS_XA;
  79     avio_skip(pb, 4);       /* Skip the XA ID */
  80     xa->out_size            =  avio_rl32(pb);
  81     avio_skip(pb, 2);       /* Skip the tag */
  82     st->codecpar->ch_layout.nb_channels = avio_rl16(pb);
  83     st->codecpar->sample_rate  = avio_rl32(pb);
  84     avio_skip(pb, 4);       /* Skip average byte rate */
  85     avio_skip(pb, 2);       /* Skip block align */
  86     avio_skip(pb, 2);       /* Skip bits-per-sample */
  87
  88     if (!st->codecpar->ch_layout.nb_channels || !st->codecpar->sample_rate)
  89         return AVERROR_INVALIDDATA;
  90
  91     st->codecpar->bit_rate = av_clip(15LL * st->codecpar->ch_layout.nb_channels * 8 *
  92                                   st->codecpar->sample_rate / 28, 0, INT_MAX);
  93
  94     avpriv_set_pts_info(st, 64, 1, st->codecpar->sample_rate);
  95     st->start_time = 0;
  96
  97     return 0;
  98 }
  99
 100 static int xa_read_packet(AVFormatContext *s,
 101                           AVPacket *pkt)
 102 {
 103     MaxisXADemuxContext *xa = s->priv_data;
 104     AVStream *st = s->streams[0];
 105     AVIOContext *pb = s->pb;
 106     unsigned int packet_size;
 107     int ret;
 108
 109     if (xa->sent_bytes >= xa->out_size)
 110         return AVERROR_EOF;
 111     /* 1 byte header and 14 bytes worth of samples * number channels per block */
 112     packet_size = 15*st->codecpar->ch_layout.nb_channels;
 113
 114     ret = av_get_packet(pb, pkt, packet_size);
 115     if(ret < 0)
 116         return ret;
 117
 118     pkt->stream_index = st->index;
 119     xa->sent_bytes += packet_size;
 120     pkt->duration = 28;
 121
 122     return ret;
 123 }
 124
 125 const FFInputFormat ff_xa_demuxer = {
 126     .p.name         = "xa",
 127     .p.long_name    = NULL_IF_CONFIG_SMALL("Maxis XA"),
 128     .priv_data_size = sizeof(MaxisXADemuxContext),
 129     .read_probe     = xa_probe,
 130     .read_header    = xa_read_header,
 131     .read_packet    = xa_read_packet,
 132 };