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
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    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
65static 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   = AVMEDIA_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
94static 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 < 0)
110        return ret;
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
121AVInputFormat 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};
129