2
* Westwood Studios AUD Format Demuxer
3
* Copyright (c) 2003 The ffmpeg Project
5
* This file is part of Libav.
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.
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.
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
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
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.
36
#include "libavutil/channel_layout.h"
37
#include "libavutil/intreadwrite.h"
41
#define AUD_HEADER_SIZE 12
42
#define AUD_CHUNK_PREAMBLE_SIZE 8
43
#define AUD_CHUNK_SIGNATURE 0x0000DEAF
45
static int wsaud_probe(AVProbeData *p)
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.
59
if (p->buf_size < AUD_HEADER_SIZE + AUD_CHUNK_PREAMBLE_SIZE)
62
/* check sample rate */
63
field = AV_RL16(&p->buf[0]);
64
if ((field < 8000) || (field > 48000))
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)
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)
77
/* read ahead to the first audio chunk and validate the first header signature */
78
if (AV_RL32(&p->buf[16]) != AUD_CHUNK_SIGNATURE)
81
/* return 1/2 certainty since this file check is a little sketchy */
82
return AVPROBE_SCORE_MAX / 2;
85
static int wsaud_read_header(AVFormatContext *s)
87
AVIOContext *pb = s->pb;
89
unsigned char header[AUD_HEADER_SIZE];
90
int sample_rate, channels, codec;
92
if (avio_read(pb, header, AUD_HEADER_SIZE) != AUD_HEADER_SIZE)
95
sample_rate = AV_RL16(&header[0]);
96
channels = (header[10] & 0x1) + 1;
99
/* initialize the audio decoder stream */
100
st = avformat_new_stream(s, NULL);
102
return AVERROR(ENOMEM);
107
av_log_ask_for_sample(s, "Stereo WS-SND1 is not supported.\n");
108
return AVERROR_PATCHWELCOME;
110
st->codec->codec_id = AV_CODEC_ID_WESTWOOD_SND1;
113
st->codec->codec_id = AV_CODEC_ID_ADPCM_IMA_WS;
114
st->codec->bits_per_coded_sample = 4;
115
st->codec->bit_rate = channels * sample_rate * 4;
118
av_log_ask_for_sample(s, "Unknown codec: %d\n", codec);
119
return AVERROR_PATCHWELCOME;
121
avpriv_set_pts_info(st, 64, 1, sample_rate);
122
st->codec->codec_type = AVMEDIA_TYPE_AUDIO;
123
st->codec->channels = channels;
124
st->codec->channel_layout = channels == 1 ? AV_CH_LAYOUT_MONO :
126
st->codec->sample_rate = sample_rate;
131
static int wsaud_read_packet(AVFormatContext *s,
134
AVIOContext *pb = s->pb;
135
unsigned char preamble[AUD_CHUNK_PREAMBLE_SIZE];
136
unsigned int chunk_size;
138
AVStream *st = s->streams[0];
140
if (avio_read(pb, preamble, AUD_CHUNK_PREAMBLE_SIZE) !=
141
AUD_CHUNK_PREAMBLE_SIZE)
144
/* validate the chunk */
145
if (AV_RL32(&preamble[4]) != AUD_CHUNK_SIGNATURE)
146
return AVERROR_INVALIDDATA;
148
chunk_size = AV_RL16(&preamble[0]);
150
if (st->codec->codec_id == AV_CODEC_ID_WESTWOOD_SND1) {
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)))
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);
163
pkt->duration = out_size;
165
ret = av_get_packet(pb, pkt, chunk_size);
166
if (ret != chunk_size)
169
/* 2 samples/byte, 1 or 2 samples per frame depending on stereo */
170
pkt->duration = (chunk_size * 2) / st->codec->channels;
172
pkt->stream_index = st->index;
177
AVInputFormat ff_wsaud_demuxer = {
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,