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 Libav.
6  *
7  * Libav 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  * Libav 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 Libav; if not, write to the Free Software
19  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
20  */
21 
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;
43 
44 static int xa_probe(AVProbeData *p)
45 {
46  int channels, srate, bits_per_sample;
47  if (p->buf_size < 24)
48  return 0;
49  switch(AV_RL32(p->buf)) {
50  case XA00_TAG:
51  case XAI0_TAG:
52  case XAJ0_TAG:
53  break;
54  default:
55  return 0;
56  }
57  channels = AV_RL16(p->buf + 10);
58  srate = AV_RL32(p->buf + 12);
59  bits_per_sample = AV_RL16(p->buf + 22);
60  if (!channels || channels > 8 || !srate || srate > 192000 ||
61  bits_per_sample < 4 || bits_per_sample > 32)
62  return 0;
63  return AVPROBE_SCORE_MAX/2;
64 }
65 
68 {
70  AVIOContext *pb = s->pb;
71  AVStream *st;
72 
73  /*Set up the XA Audio Decoder*/
74  st = avformat_new_stream(s, NULL);
75  if (!st)
76  return AVERROR(ENOMEM);
77 
80  avio_skip(pb, 4); /* Skip the XA ID */
81  xa->out_size = avio_rl32(pb);
82  avio_skip(pb, 2); /* Skip the tag */
83  st->codec->channels = avio_rl16(pb);
84  st->codec->sample_rate = avio_rl32(pb);
85  /* Value in file is average byte rate*/
86  st->codec->bit_rate = avio_rl32(pb) * 8;
87  st->codec->block_align = avio_rl16(pb);
89 
90  avpriv_set_pts_info(st, 64, 1, st->codec->sample_rate);
91 
92  return 0;
93 }
94 
96  AVPacket *pkt)
97 {
99  AVStream *st = s->streams[0];
100  AVIOContext *pb = s->pb;
101  unsigned int packet_size;
102  int ret;
103 
104  if(xa->sent_bytes > xa->out_size)
105  return AVERROR(EIO);
106  /* 1 byte header and 14 bytes worth of samples * number channels per block */
107  packet_size = 15*st->codec->channels;
108 
109  ret = av_get_packet(pb, pkt, packet_size);
110  if(ret < 0)
111  return ret;
112 
113  pkt->stream_index = st->index;
114  xa->sent_bytes += packet_size;
115  pkt->pts = xa->audio_frame_counter;
116  /* 14 bytes Samples per channel with 2 samples per byte */
117  xa->audio_frame_counter += 28 * st->codec->channels;
118 
119  return ret;
120 }
121 
123  .name = "xa",
124  .long_name = NULL_IF_CONFIG_SMALL("Maxis XA File Format"),
125  .priv_data_size = sizeof(MaxisXADemuxContext),
126  .read_probe = xa_probe,
129 };
Bytestream IO Context.
Definition: avio.h:68
static int xa_probe(AVProbeData *p)
Definition: xa.c:44
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 pts for a given stream.
Definition: utils.c:3828
int index
stream index in AVFormatContext
Definition: avformat.h:621
int block_align
number of bytes per packet if constant and known or 0 Used by some WAV based audio codecs...
Definition: avcodec.h:1751
Format I/O context.
Definition: avformat.h:863
AVInputFormat ff_xa_demuxer
Definition: xa.c:122
AVStream ** streams
Definition: avformat.h:908
static int read_header(FFV1Context *f)
Definition: ffv1.c:1513
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:269
int bits_per_coded_sample
bits per sample/pixel from the demuxer (needed for huffyuv).
Definition: avcodec.h:1974
#define XAJ0_TAG
Definition: xa.c:36
unsigned int avio_rl32(AVIOContext *s)
Definition: aviobuf.c:738
#define AVERROR(e)
Definition: error.h:43
#define NULL_IF_CONFIG_SMALL(x)
Return NULL if CONFIG_SMALL is true, otherwise the argument without modification. ...
Definition: internal.h:191
AV_RL32
Definition: bytestream.h:89
AVStream * avformat_new_stream(AVFormatContext *s, AVCodec *c)
Add a new stream to a media file.
Definition: utils.c:2776
static int xa_read_packet(AVFormatContext *s, AVPacket *pkt)
Definition: xa.c:95
AVCodecContext * codec
codec context
Definition: avformat.h:623
int buf_size
Size of buf except extra allocated bytes.
Definition: avformat.h:342
uint32_t audio_frame_counter
Definition: xa.c:41
unsigned char * buf
Buffer must have AVPROBE_PADDING_SIZE of extra allocated bytes filled with zero.
Definition: avformat.h:341
static int xa_read_header(AVFormatContext *s, AVFormatParameters *ap)
Definition: xa.c:66
int bit_rate
the average bitrate
Definition: avcodec.h:1340
#define XAI0_TAG
Definition: xa.c:35
static av_always_inline int64_t avio_skip(AVIOContext *s, int64_t offset)
Skip given number of bytes forward.
Definition: avio.h:483
uint32_t sent_bytes
Definition: xa.c:40
static int read_probe(AVProbeData *p)
Definition: img2.c:185
Stream structure.
Definition: avformat.h:620
NULL
Definition: eval.c:50
enum AVMediaType codec_type
Definition: avcodec.h:1574
int sample_rate
samples per second
Definition: avcodec.h:1456
AVIOContext * pb
Definition: avformat.h:896
static int read_packet(AVFormatContext *ctx, AVPacket *pkt)
Definition: libcdio.c:109
This structure contains the data a format has to probe a file.
Definition: avformat.h:339
#define XA00_TAG
Definition: xa.c:34
#define AVPROBE_SCORE_MAX
maximum score, half of that is used for file-extension-based detection
Definition: avformat.h:345
unsigned int avio_rl16(AVIOContext *s)
Definition: aviobuf.c:722
Main libavformat public API header.
AV_WL32 AV_WL24 AV_RL16
Definition: bytestream.h:89
int channels
number of audio channels
Definition: avcodec.h:1457
void * priv_data
Format private data.
Definition: avformat.h:883
struct MaxisXADemuxContext MaxisXADemuxContext
const char * name
A comma separated list of short names for the format.
Definition: avformat.h:460
int stream_index
Definition: avcodec.h:910
int64_t pts
Presentation timestamp in AVStream->time_base units; the time at which the decompressed packet will b...
Definition: avcodec.h:901
enum CodecID codec_id
Definition: avcodec.h:1575