FFmpeg: libavformat/xa.c Source File

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;
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_EXTENSION;
63 }
64 
65  static int xa_read_header(AVFormatContext *s)
66 {
67  MaxisXADemuxContext *xa = s->priv_data;
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 
76  st->codec->codec_type = AVMEDIA_TYPE_AUDIO;
77  st->codec->codec_id = AV_CODEC_ID_ADPCM_EA_MAXIS_XA;
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->codec->channels = avio_rl16(pb);
82  st->codec->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->codec->channels || !st->codec->sample_rate)
88  return AVERROR_INVALIDDATA;
89 
90  st->codec->bit_rate = av_clip(15LL * st->codec->channels * 8 *
91  st->codec->sample_rate / 28, 0, INT_MAX);
92 
93  avpriv_set_pts_info(st, 64, 1, st->codec->sample_rate);
94  st->start_time = 0;
95 
96  return 0;
97 }
98 
99  static int xa_read_packet(AVFormatContext *s,
100  AVPacket *pkt)
101 {
102  MaxisXADemuxContext *xa = s->priv_data;
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->codec->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 
124  AVInputFormat ff_xa_demuxer = {
125  .name = "xa",
126  .long_name = NULL_IF_CONFIG_SMALL("Maxis XA"),
127  .priv_data_size = sizeof(MaxisXADemuxContext),
128  .read_probe = xa_probe,
129  .read_header = xa_read_header,
130  .read_packet = xa_read_packet,
131 };
NULL
#define NULL
Definition: coverity.c:32
s
const char * s
Definition: avisynth_c.h:631
AVIOContext
Bytestream IO Context.
Definition: avio.h:111
xa_probe
static int xa_probe(AVProbeData *p)
Definition: xa.c:43
AVERROR_INVALIDDATA
#define AVERROR_INVALIDDATA
Invalid data found when processing input.
Definition: error.h:59
MaxisXADemuxContext::out_size
uint32_t out_size
Definition: xa.c:39
AVCodecContext::bit_rate
int64_t bit_rate
the average bitrate
Definition: avcodec.h:1597
avpriv_set_pts_info
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:4149
AVStream::index
int index
stream index in AVFormatContext
Definition: avformat.h:878
avio_skip
int64_t avio_skip(AVIOContext *s, int64_t offset)
Skip given number of bytes forward.
Definition: aviobuf.c:282
pkt
static AVPacket pkt
Definition: demuxing_decoding.c:54
AV_RL16
uint64_t_TMPL AV_WL64 unsigned int_TMPL AV_WL32 unsigned int_TMPL AV_WL24 unsigned int_TMPL AV_RL16
Definition: bytestream.h:87
AVFormatContext
Format I/O context.
Definition: avformat.h:1314
ff_xa_demuxer
AVInputFormat ff_xa_demuxer
Definition: xa.c:124
AVPacket::duration
int64_t duration
Duration of this packet in AVStream->time_base units, 0 if unknown.
Definition: avcodec.h:1485
avformat_new_stream
AVStream * avformat_new_stream(AVFormatContext *s, const AVCodec *c)
Add a new stream to a media file.
Definition: utils.c:3805
AVFormatContext::streams
AVStream ** streams
A list of all streams in the file.
Definition: avformat.h:1382
AVERROR_EOF
#define AVERROR_EOF
End of file.
Definition: error.h:55
av_get_packet
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:252
XAJ0_TAG
#define XAJ0_TAG
Definition: xa.c:36
avio_rl32
unsigned int avio_rl32(AVIOContext *s)
Definition: aviobuf.c:667
AVERROR
#define AVERROR(e)
Definition: error.h:43
NULL_IF_CONFIG_SMALL
#define NULL_IF_CONFIG_SMALL(x)
Return NULL if CONFIG_SMALL is true, otherwise the argument without modification. ...
Definition: internal.h:176
AVMEDIA_TYPE_AUDIO
Definition: avutil.h:194
xa_read_packet
static int xa_read_packet(AVFormatContext *s, AVPacket *pkt)
Definition: xa.c:99
AVStream::codec
AVCodecContext * codec
Codec context associated with this stream.
Definition: avformat.h:896
AVProbeData::buf_size
int buf_size
Size of buf except extra allocated bytes.
Definition: avformat.h:463
AVProbeData::buf
unsigned char * buf
Buffer must have AVPROBE_PADDING_SIZE of extra allocated bytes filled with zero.
Definition: avformat.h:462
read_probe
static int read_probe(AVProbeData *pd)
Definition: jvdec.c:55
XAI0_TAG
#define XAI0_TAG
Definition: xa.c:35
MaxisXADemuxContext::sent_bytes
uint32_t sent_bytes
Definition: xa.c:40
read_header
static int read_header(FFV1Context *f)
Definition: ffv1dec.c:638
AVStream
Stream structure.
Definition: avformat.h:877
read_packet
static int read_packet(void *opaque, uint8_t *buf, int buf_size)
Definition: avio_reading.c:42
AVCodecContext::codec_type
enum AVMediaType codec_type
Definition: avcodec.h:1540
AV_CODEC_ID_ADPCM_EA_MAXIS_XA
Definition: avcodec.h:384
AVCodecContext::codec_id
enum AVCodecID codec_id
Definition: avcodec.h:1549
AVCodecContext::sample_rate
int sample_rate
samples per second
Definition: avcodec.h:2287
AVFormatContext::pb
AVIOContext * pb
I/O context.
Definition: avformat.h:1356
AVPROBE_SCORE_EXTENSION
#define AVPROBE_SCORE_EXTENSION
score for file extension
Definition: avformat.h:470
AVProbeData
This structure contains the data a format has to probe a file.
Definition: avformat.h:460
XA00_TAG
#define XA00_TAG
Definition: xa.c:34
avio_rl16
unsigned int avio_rl16(AVIOContext *s)
Definition: aviobuf.c:651
avformat.h
Main libavformat public API header.
xa_read_header
static int xa_read_header(AVFormatContext *s)
Definition: xa.c:65
AVStream::start_time
int64_t start_time
Decoding: pts of the first frame of the stream in presentation order, in stream time base...
Definition: avformat.h:929
AVCodecContext::channels
int channels
number of audio channels
Definition: avcodec.h:2288
AVFormatContext::priv_data
void * priv_data
Format private data.
Definition: avformat.h:1342
AVInputFormat::name
const char * name
A comma separated list of short names for the format.
Definition: avformat.h:661
AVPacket::stream_index
int stream_index
Definition: avcodec.h:1469
AV_RL32
uint64_t_TMPL AV_WL64 unsigned int_TMPL AV_RL32
Definition: bytestream.h:87
AVPacket
This structure stores compressed data.
Definition: avcodec.h:1444
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