FFmpeg
xa.c
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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 "internal.h"
33 
34 #define XA00_TAG MKTAG('X', 'A', 0, 0)
35 #define XAI0_TAG MKTAG('X', 'A', 'I', 0)
36 #define XAJ0_TAG MKTAG('X', 'A', 'J', 0)
37 
38 typedef struct MaxisXADemuxContext {
39  uint32_t out_size;
40  uint32_t sent_bytes;
42 
43 static int xa_probe(const 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;
63 }
64 
66 {
68  AVIOContext *pb = s->pb;
69  AVStream *st;
70 
71  /*Set up the XA Audio Decoder*/
72  st = avformat_new_stream(s, NULL);
73  if (!st)
74  return AVERROR(ENOMEM);
75 
78  avio_skip(pb, 4); /* Skip the XA ID */
79  xa->out_size = avio_rl32(pb);
80  avio_skip(pb, 2); /* Skip the tag */
81  st->codecpar->channels = avio_rl16(pb);
82  st->codecpar->sample_rate = avio_rl32(pb);
83  avio_skip(pb, 4); /* Skip average byte rate */
84  avio_skip(pb, 2); /* Skip block align */
85  avio_skip(pb, 2); /* Skip bits-per-sample */
86 
87  if (!st->codecpar->channels || !st->codecpar->sample_rate)
88  return AVERROR_INVALIDDATA;
89 
90  st->codecpar->bit_rate = av_clip(15LL * st->codecpar->channels * 8 *
91  st->codecpar->sample_rate / 28, 0, INT_MAX);
92 
93  avpriv_set_pts_info(st, 64, 1, st->codecpar->sample_rate);
94  st->start_time = 0;
95 
96  return 0;
97 }
98 
100  AVPacket *pkt)
101 {
103  AVStream *st = s->streams[0];
104  AVIOContext *pb = s->pb;
105  unsigned int packet_size;
106  int ret;
107 
108  if (xa->sent_bytes >= xa->out_size)
109  return AVERROR_EOF;
110  /* 1 byte header and 14 bytes worth of samples * number channels per block */
111  packet_size = 15*st->codecpar->channels;
112 
113  ret = av_get_packet(pb, pkt, packet_size);
114  if(ret < 0)
115  return ret;
116 
117  pkt->stream_index = st->index;
118  xa->sent_bytes += packet_size;
119  pkt->duration = 28;
120 
121  return ret;
122 }
123 
125  .name = "xa",
126  .long_name = NULL_IF_CONFIG_SMALL("Maxis XA"),
127  .priv_data_size = sizeof(MaxisXADemuxContext),
128  .read_probe = xa_probe,
131 };
#define NULL
Definition: coverity.c:32
Bytestream IO Context.
Definition: avio.h:161
#define AVERROR_INVALIDDATA
Invalid data found when processing input.
Definition: error.h:59
uint32_t out_size
Definition: xa.c:39
void avpriv_set_pts_info(AVStream *s, int pts_wrap_bits, unsigned int pts_num, unsigned int pts_den)
Set the time base and wrapping info for a given stream.
Definition: utils.c:4929
channels
Definition: aptx.c:30
enum AVCodecID codec_id
Specific type of the encoded data (the codec used).
Definition: avcodec.h:3968
int index
stream index in AVFormatContext
Definition: avformat.h:882
int64_t avio_skip(AVIOContext *s, int64_t offset)
Skip given number of bytes forward.
Definition: aviobuf.c:334
static AVPacket pkt
uint64_t_TMPL AV_WL64 unsigned int_TMPL AV_WL32 unsigned int_TMPL AV_WL24 unsigned int_TMPL AV_RL16
Definition: bytestream.h:87
Format I/O context.
Definition: avformat.h:1358
AVInputFormat ff_xa_demuxer
Definition: xa.c:124
int64_t duration
Duration of this packet in AVStream->time_base units, 0 if unknown.
Definition: avcodec.h:1498
AVStream * avformat_new_stream(AVFormatContext *s, const AVCodec *c)
Add a new stream to a media file.
Definition: utils.c:4502
AVStream ** streams
A list of all streams in the file.
Definition: avformat.h:1426
#define AVERROR_EOF
End of file.
Definition: error.h:55
int av_get_packet(AVIOContext *s, AVPacket *pkt, int size)
Allocate and read the payload of a packet and initialize its fields with default values.
Definition: utils.c:310
int64_t bit_rate
The average bitrate of the encoded data (in bits per second).
Definition: avcodec.h:3997
#define XAJ0_TAG
Definition: xa.c:36
unsigned int avio_rl32(AVIOContext *s)
Definition: aviobuf.c:772
#define NULL_IF_CONFIG_SMALL(x)
Return NULL if CONFIG_SMALL is true, otherwise the argument without modification. ...
Definition: internal.h:186
enum AVMediaType codec_type
General type of the encoded data.
Definition: avcodec.h:3964
static int xa_read_packet(AVFormatContext *s, AVPacket *pkt)
Definition: xa.c:99
int buf_size
Size of buf except extra allocated bytes.
Definition: avformat.h:449
unsigned char * buf
Buffer must have AVPROBE_PADDING_SIZE of extra allocated bytes filled with zero.
Definition: avformat.h:448
#define XAI0_TAG
Definition: xa.c:35
uint32_t sent_bytes
Definition: xa.c:40
#define s(width, name)
Definition: cbs_vp9.c:257
static int read_header(FFV1Context *f)
Definition: ffv1dec.c:530
Stream structure.
Definition: avformat.h:881
static int read_packet(void *opaque, uint8_t *buf, int buf_size)
Definition: avio_reading.c:42
static int xa_probe(const AVProbeData *p)
Definition: xa.c:43
AVIOContext * pb
I/O context.
Definition: avformat.h:1400
#define AVPROBE_SCORE_EXTENSION
score for file extension
Definition: avformat.h:456
This structure contains the data a format has to probe a file.
Definition: avformat.h:446
#define XA00_TAG
Definition: xa.c:34
static int read_probe(const AVProbeData *pd)
Definition: jvdec.c:55
int sample_rate
Audio only.
Definition: avcodec.h:4078
unsigned int avio_rl16(AVIOContext *s)
Definition: aviobuf.c:756
Main libavformat public API header.
static int xa_read_header(AVFormatContext *s)
Definition: xa.c:65
int64_t start_time
Decoding: pts of the first frame of the stream in presentation order, in stream time base...
Definition: avformat.h:920
void * priv_data
Format private data.
Definition: avformat.h:1386
int channels
Audio only.
Definition: avcodec.h:4074
const char * name
A comma separated list of short names for the format.
Definition: avformat.h:654
AVCodecParameters * codecpar
Codec parameters associated with this stream.
Definition: avformat.h:1028
int stream_index
Definition: avcodec.h:1482
Filter the word “frame” indicates either a video frame or a group of audio as stored in an AVFrame structure Format for each input and each output the list of supported formats For video that means pixel format For audio that means channel sample they are references to shared objects When the negotiation mechanism computes the intersection of the formats supported at each end of a all references to both lists are replaced with a reference to the intersection And when a single format is eventually chosen for a link amongst the remaining all references to the list are updated That means that if a filter requires that its input and output have the same format amongst a supported all it has to do is use a reference to the same list of formats query_formats can leave some formats unset and return AVERROR(EAGAIN) to cause the negotiation mechanism toagain later.That can be used by filters with complex requirements to use the format negotiated on one link to set the formats supported on another.Frame references ownership and permissions
uint64_t_TMPL AV_WL64 unsigned int_TMPL AV_RL32
Definition: bytestream.h:87
This structure stores compressed data.
Definition: avcodec.h:1457