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 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
  37 typedef struct MaxisXADemuxContext {
  38     uint32_t out_size;
  39     uint32_t sent_bytes;
  40     uint32_t audio_frame_counter;
  41 } MaxisXADemuxContext;
  42
  43 static 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
  65 static 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   = CODEC_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
  94 static 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 != packet_size)
 110         return AVERROR(EIO);
 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
 121 AVInputFormat 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 };