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