FFmpeg
westwood_aud.c
Go to the documentation of this file.
1 /*
2  * Westwood Studios AUD Format Demuxer
3  * Copyright (c) 2003 The FFmpeg project
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  * Westwood Studios AUD file demuxer
25  * by Mike Melanson (melanson@pcisys.net)
26  * for more information on the Westwood file formats, visit:
27  * http://www.pcisys.net/~melanson/codecs/
28  * http://www.geocities.com/SiliconValley/8682/aud3.txt
29  *
30  * Implementation note: There is no definite file signature for AUD files.
31  * The demuxer uses a probabilistic strategy for content detection. This
32  * entails performing sanity checks on certain header values in order to
33  * qualify a file. Refer to wsaud_probe() for the precise parameters.
34  */
35 
37 #include "libavutil/intreadwrite.h"
38 #include "avformat.h"
39 #include "internal.h"
40 
41 #define AUD_HEADER_SIZE 12
42 #define AUD_CHUNK_PREAMBLE_SIZE 8
43 #define AUD_CHUNK_SIGNATURE 0x0000DEAF
44 
45 static int wsaud_probe(const AVProbeData *p)
46 {
47  int field;
48 
49  /* Probabilistic content detection strategy: There is no file signature
50  * so perform sanity checks on various header parameters:
51  * 8000 <= sample rate (16 bits) <= 48000 ==> 40001 acceptable numbers
52  * flags <= 0x03 (2 LSBs are used) ==> 4 acceptable numbers
53  * compression type (8 bits) = 1 or 99 ==> 2 acceptable numbers
54  * first audio chunk signature (32 bits) ==> 1 acceptable number
55  * The number space contains 2^64 numbers. There are 40001 * 4 * 2 * 1 =
56  * 320008 acceptable number combinations.
57  */
58 
60  return 0;
61 
62  /* check sample rate */
63  field = AV_RL16(&p->buf[0]);
64  if ((field < 8000) || (field > 48000))
65  return 0;
66 
67  /* enforce the rule that the top 6 bits of this flags field are reserved (0);
68  * this might not be true, but enforce it until deemed unnecessary */
69  if (p->buf[10] & 0xFC)
70  return 0;
71 
72  if (p->buf[11] != 99 && p->buf[11] != 1)
73  return 0;
74 
75  /* read ahead to the first audio chunk and validate the first header signature */
76  if (AV_RL32(&p->buf[16]) != AUD_CHUNK_SIGNATURE)
77  return 0;
78 
79  /* return 1/2 certainty since this file check is a little sketchy */
81 }
82 
84 {
85  AVIOContext *pb = s->pb;
86  AVStream *st;
87  unsigned char header[AUD_HEADER_SIZE];
88  int sample_rate, channels, codec;
89 
91  return AVERROR(EIO);
92 
93  sample_rate = AV_RL16(&header[0]);
94  channels = (header[10] & 0x1) + 1;
95  codec = header[11];
96 
97  /* initialize the audio decoder stream */
98  st = avformat_new_stream(s, NULL);
99  if (!st)
100  return AVERROR(ENOMEM);
101 
102  switch (codec) {
103  case 1:
104  if (channels != 1) {
105  avpriv_request_sample(s, "Stereo WS-SND1");
106  return AVERROR_PATCHWELCOME;
107  }
109  break;
110  case 99:
113  st->codecpar->bit_rate = channels * sample_rate * 4;
114  break;
115  default:
116  avpriv_request_sample(s, "Unknown codec: %d", codec);
117  return AVERROR_PATCHWELCOME;
118  }
119  avpriv_set_pts_info(st, 64, 1, sample_rate);
121  st->codecpar->channels = channels;
125 
126  return 0;
127 }
128 
130  AVPacket *pkt)
131 {
132  AVIOContext *pb = s->pb;
133  unsigned char preamble[AUD_CHUNK_PREAMBLE_SIZE];
134  unsigned int chunk_size;
135  int ret = 0;
136  AVStream *st = s->streams[0];
137 
138  if (avio_read(pb, preamble, AUD_CHUNK_PREAMBLE_SIZE) !=
140  return AVERROR(EIO);
141 
142  /* validate the chunk */
143  if (AV_RL32(&preamble[4]) != AUD_CHUNK_SIGNATURE)
144  return AVERROR_INVALIDDATA;
145 
146  chunk_size = AV_RL16(&preamble[0]);
147 
149  /* For Westwood SND1 audio we need to add the output size and input
150  size to the start of the packet to match what is in VQA.
151  Specifically, this is needed to signal when a packet should be
152  decoding as raw 8-bit pcm or variable-size ADPCM. */
153  int out_size = AV_RL16(&preamble[2]);
154  if ((ret = av_new_packet(pkt, chunk_size + 4)) < 0)
155  return ret;
156  if ((ret = avio_read(pb, &pkt->data[4], chunk_size)) != chunk_size)
157  return ret < 0 ? ret : AVERROR(EIO);
158  AV_WL16(&pkt->data[0], out_size);
159  AV_WL16(&pkt->data[2], chunk_size);
160 
161  pkt->duration = out_size;
162  } else {
163  ret = av_get_packet(pb, pkt, chunk_size);
164  if (ret != chunk_size)
165  return AVERROR(EIO);
166 
167  if (st->codecpar->channels <= 0) {
168  av_log(s, AV_LOG_ERROR, "invalid number of channels %d\n",
169  st->codecpar->channels);
170  return AVERROR_INVALIDDATA;
171  }
172 
173  /* 2 samples/byte, 1 or 2 samples per frame depending on stereo */
174  pkt->duration = (chunk_size * 2) / st->codecpar->channels;
175  }
176  pkt->stream_index = st->index;
177 
178  return ret;
179 }
180 
182  .name = "wsaud",
183  .long_name = NULL_IF_CONFIG_SMALL("Westwood Studios audio"),
184  .read_probe = wsaud_probe,
185  .read_header = wsaud_read_header,
186  .read_packet = wsaud_read_packet,
187 };
AVERROR
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
avformat_new_stream
AVStream * avformat_new_stream(AVFormatContext *s, const AVCodec *c)
Add a new stream to a media file.
Definition: utils.c:4526
AVCodecParameters::codec_type
enum AVMediaType codec_type
General type of the encoded data.
Definition: codec_par.h:56
AV_CH_LAYOUT_MONO
#define AV_CH_LAYOUT_MONO
Definition: channel_layout.h:85
out_size
int out_size
Definition: movenc.c:55
AVPacket::data
uint8_t * data
Definition: packet.h:355
AUD_CHUNK_PREAMBLE_SIZE
#define AUD_CHUNK_PREAMBLE_SIZE
Definition: westwood_aud.c:42
AVPacket::duration
int64_t duration
Duration of this packet in AVStream->time_base units, 0 if unknown.
Definition: packet.h:373
AVProbeData::buf_size
int buf_size
Size of buf except extra allocated bytes.
Definition: avformat.h:444
sample_rate
sample_rate
Definition: ffmpeg_filter.c:192
AVCodecParameters::channels
int channels
Audio only.
Definition: codec_par.h:166
wsaud_read_header
static int wsaud_read_header(AVFormatContext *s)
Definition: westwood_aud.c:83
AV_CH_LAYOUT_STEREO
#define AV_CH_LAYOUT_STEREO
Definition: channel_layout.h:86
AV_LOG_ERROR
#define AV_LOG_ERROR
Something went wrong and cannot losslessly be recovered.
Definition: log.h:176
AVInputFormat
Definition: avformat.h:636
intreadwrite.h
s
#define s(width, name)
Definition: cbs_vp9.c:257
av_new_packet
int av_new_packet(AVPacket *pkt, int size)
Allocate the payload of a packet and initialize its fields with default values.
Definition: avpacket.c:88
AVInputFormat::name
const char * name
A comma separated list of short names for the format.
Definition: avformat.h:641
AVProbeData::buf
unsigned char * buf
Buffer must have AVPROBE_PADDING_SIZE of extra allocated bytes filled with zero.
Definition: avformat.h:443
AVMEDIA_TYPE_AUDIO
@ AVMEDIA_TYPE_AUDIO
Definition: avutil.h:202
channels
channels
Definition: aptx.h:33
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:90
wsaud_probe
static int wsaud_probe(const AVProbeData *p)
Definition: westwood_aud.c:45
field
it s the only field you need to keep assuming you have a context There is some magic you don t need to care about around this field
Definition: writing_filters.txt:78
AVFormatContext
Format I/O context.
Definition: avformat.h:1335
internal.h
AVStream::codecpar
AVCodecParameters * codecpar
Codec parameters associated with this stream.
Definition: avformat.h:1012
NULL
#define NULL
Definition: coverity.c:32
AVERROR_PATCHWELCOME
#define AVERROR_PATCHWELCOME
Not yet implemented in FFmpeg, patches welcome.
Definition: error.h:62
AV_CODEC_ID_ADPCM_IMA_WS
@ AV_CODEC_ID_ADPCM_IMA_WS
Definition: codec_id.h:344
AUD_CHUNK_SIGNATURE
#define AUD_CHUNK_SIGNATURE
Definition: westwood_aud.c:43
AVProbeData
This structure contains the data a format has to probe a file.
Definition: avformat.h:441
AVPROBE_SCORE_EXTENSION
#define AVPROBE_SCORE_EXTENSION
score for file extension
Definition: avformat.h:451
AVCodecParameters::sample_rate
int sample_rate
Audio only.
Definition: codec_par.h:170
AUD_HEADER_SIZE
#define AUD_HEADER_SIZE
Definition: westwood_aud.c:41
AVIOContext
Bytestream IO Context.
Definition: avio.h:161
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:188
ff_wsaud_demuxer
AVInputFormat ff_wsaud_demuxer
Definition: westwood_aud.c:181
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:4948
header
static const uint8_t header[24]
Definition: sdr2.c:67
AV_WL16
#define AV_WL16(p, v)
Definition: intreadwrite.h:412
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:307
ret
ret
Definition: filter_design.txt:187
AVStream
Stream structure.
Definition: avformat.h:865
avformat.h
AV_CODEC_ID_WESTWOOD_SND1
@ AV_CODEC_ID_WESTWOOD_SND1
Definition: codec_id.h:427
AV_RL32
uint64_t_TMPL AV_WL64 unsigned int_TMPL AV_RL32
Definition: bytestream.h:88
AVStream::index
int index
stream index in AVFormatContext
Definition: avformat.h:866
channel_layout.h
pkt
static AVPacket pkt
Definition: demuxing_decoding.c:54
avio_read
int avio_read(AVIOContext *s, unsigned char *buf, int size)
Read size bytes from AVIOContext into buf.
Definition: aviobuf.c:625
AVPacket::stream_index
int stream_index
Definition: packet.h:357
AVCodecParameters::bits_per_coded_sample
int bits_per_coded_sample
The number of bits per sample in the codedwords.
Definition: codec_par.h:102
avpriv_request_sample
#define avpriv_request_sample(...)
Definition: tableprint_vlc.h:39
wsaud_read_packet
static int wsaud_read_packet(AVFormatContext *s, AVPacket *pkt)
Definition: westwood_aud.c:129
AVCodecParameters::codec_id
enum AVCodecID codec_id
Specific type of the encoded data (the codec used).
Definition: codec_par.h:60
AVPacket
This structure stores compressed data.
Definition: packet.h:332
AVCodecParameters::channel_layout
uint64_t channel_layout
Audio only.
Definition: codec_par.h:162
AVCodecParameters::bit_rate
int64_t bit_rate
The average bitrate of the encoded data (in bits per second).
Definition: codec_par.h:89
av_log
#define av_log(a,...)
Definition: tableprint_vlc.h:28
AVERROR_INVALIDDATA
#define AVERROR_INVALIDDATA
Invalid data found when processing input.
Definition: error.h:59