Libav
westwood_aud.c
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1 /*
2  * Westwood Studios AUD Format Demuxer
3  * Copyright (c) 2003 The ffmpeg Project
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 
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(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  /* note: only check for WS IMA (type 99) right now since there is no
73  * support for type 1 */
74  if (p->buf[11] != 99 && p->buf[11] != 1)
75  return 0;
76 
77  /* read ahead to the first audio chunk and validate the first header signature */
78  if (AV_RL32(&p->buf[16]) != AUD_CHUNK_SIGNATURE)
79  return 0;
80 
81  /* return 1/2 certainty since this file check is a little sketchy */
83 }
84 
86 {
87  AVIOContext *pb = s->pb;
88  AVStream *st;
89  unsigned char header[AUD_HEADER_SIZE];
90  int sample_rate, channels, codec;
91 
92  if (avio_read(pb, header, AUD_HEADER_SIZE) != AUD_HEADER_SIZE)
93  return AVERROR(EIO);
94 
95  sample_rate = AV_RL16(&header[0]);
96  channels = (header[10] & 0x1) + 1;
97  codec = header[11];
98 
99  /* initialize the audio decoder stream */
100  st = avformat_new_stream(s, NULL);
101  if (!st)
102  return AVERROR(ENOMEM);
103 
104  switch (codec) {
105  case 1:
106  if (channels != 1) {
107  avpriv_request_sample(s, "Stereo WS-SND1");
108  return AVERROR_PATCHWELCOME;
109  }
111  break;
112  case 99:
114  st->codec->bits_per_coded_sample = 4;
115  st->codec->bit_rate = channels * sample_rate * 4;
116  break;
117  default:
118  avpriv_request_sample(s, "Unknown codec: %d", codec);
119  return AVERROR_PATCHWELCOME;
120  }
121  avpriv_set_pts_info(st, 64, 1, sample_rate);
123  st->codec->channels = channels;
124  st->codec->channel_layout = channels == 1 ? AV_CH_LAYOUT_MONO :
126  st->codec->sample_rate = sample_rate;
127 
128  return 0;
129 }
130 
132  AVPacket *pkt)
133 {
134  AVIOContext *pb = s->pb;
135  unsigned char preamble[AUD_CHUNK_PREAMBLE_SIZE];
136  unsigned int chunk_size;
137  int ret = 0;
138  AVStream *st = s->streams[0];
139 
140  if (avio_read(pb, preamble, AUD_CHUNK_PREAMBLE_SIZE) !=
142  return AVERROR(EIO);
143 
144  /* validate the chunk */
145  if (AV_RL32(&preamble[4]) != AUD_CHUNK_SIGNATURE)
146  return AVERROR_INVALIDDATA;
147 
148  chunk_size = AV_RL16(&preamble[0]);
149 
151  /* For Westwood SND1 audio we need to add the output size and input
152  size to the start of the packet to match what is in VQA.
153  Specifically, this is needed to signal when a packet should be
154  decoding as raw 8-bit pcm or variable-size ADPCM. */
155  int out_size = AV_RL16(&preamble[2]);
156  if ((ret = av_new_packet(pkt, chunk_size + 4)))
157  return ret;
158  if ((ret = avio_read(pb, &pkt->data[4], chunk_size)) != chunk_size)
159  return ret < 0 ? ret : AVERROR(EIO);
160  AV_WL16(&pkt->data[0], out_size);
161  AV_WL16(&pkt->data[2], chunk_size);
162 
163  pkt->duration = out_size;
164  } else {
165  ret = av_get_packet(pb, pkt, chunk_size);
166  if (ret != chunk_size)
167  return AVERROR(EIO);
168 
169  /* 2 samples/byte, 1 or 2 samples per frame depending on stereo */
170  pkt->duration = (chunk_size * 2) / st->codec->channels;
171  }
172  pkt->stream_index = st->index;
173 
174  return ret;
175 }
176 
178  .name = "wsaud",
179  .long_name = NULL_IF_CONFIG_SMALL("Westwood Studios audio"),
180  .read_probe = wsaud_probe,
181  .read_header = wsaud_read_header,
182  .read_packet = wsaud_read_packet,
183 };
Bytestream IO Context.
Definition: avio.h:68
#define AVERROR_INVALIDDATA
Invalid data found when processing input.
Definition: error.h:54
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:2800
int index
stream index in AVFormatContext
Definition: avformat.h:700
#define AV_RL16
Definition: intreadwrite.h:42
#define AV_CH_LAYOUT_STEREO
#define AUD_CHUNK_PREAMBLE_SIZE
Definition: westwood_aud.c:42
Format I/O context.
Definition: avformat.h:922
static int wsaud_read_header(AVFormatContext *s)
Definition: westwood_aud.c:85
void void avpriv_request_sample(void *avc, const char *msg,...) av_printf_format(2
Log a generic warning message about a missing feature.
AVStream * avformat_new_stream(AVFormatContext *s, const AVCodec *c)
Add a new stream to a media file.
Definition: utils.c:2497
AVStream ** streams
A list of all streams in the file.
Definition: avformat.h:990
uint8_t * data
Definition: avcodec.h:967
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:117
int bits_per_coded_sample
bits per sample/pixel from the demuxer (needed for huffyuv).
Definition: avcodec.h:2501
int duration
Duration of this packet in AVStream->time_base units, 0 if unknown.
Definition: avcodec.h:985
int avio_read(AVIOContext *s, unsigned char *buf, int size)
Read size bytes from AVIOContext into buf.
Definition: aviobuf.c:452
int av_new_packet(AVPacket *pkt, int size)
Allocate the payload of a packet and initialize its fields with default values.
Definition: avpacket.c:81
#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:150
#define AUD_CHUNK_SIGNATURE
Definition: westwood_aud.c:43
uint64_t channel_layout
Audio channel layout.
Definition: avcodec.h:1846
AVCodecContext * codec
Codec context associated with this stream.
Definition: avformat.h:718
int buf_size
Size of buf except extra allocated bytes.
Definition: avformat.h:398
unsigned char * buf
Buffer must have AVPROBE_PADDING_SIZE of extra allocated bytes filled with zero.
Definition: avformat.h:397
int bit_rate
the average bitrate
Definition: avcodec.h:1108
audio channel layout utility functions
#define AV_RL32
Definition: intreadwrite.h:146
#define AUD_HEADER_SIZE
Definition: westwood_aud.c:41
Stream structure.
Definition: avformat.h:699
#define AVERROR_PATCHWELCOME
Not yet implemented in Libav, patches welcome.
Definition: error.h:57
NULL
Definition: eval.c:55
enum AVMediaType codec_type
Definition: avcodec.h:1052
enum AVCodecID codec_id
Definition: avcodec.h:1061
AVInputFormat ff_wsaud_demuxer
Definition: westwood_aud.c:177
int sample_rate
samples per second
Definition: avcodec.h:1785
AVIOContext * pb
I/O context.
Definition: avformat.h:964
#define AVPROBE_SCORE_EXTENSION
score for file extension
Definition: avformat.h:402
This structure contains the data a format has to probe a file.
Definition: avformat.h:395
Main libavformat public API header.
static int wsaud_read_packet(AVFormatContext *s, AVPacket *pkt)
Definition: westwood_aud.c:131
static int wsaud_probe(AVProbeData *p)
Definition: westwood_aud.c:45
int channels
number of audio channels
Definition: avcodec.h:1786
const char * name
A comma separated list of short names for the format.
Definition: avformat.h:525
#define AV_WL16(p, d)
Definition: intreadwrite.h:225
int stream_index
Definition: avcodec.h:969
#define AV_CH_LAYOUT_MONO
This structure stores compressed data.
Definition: avcodec.h:944