2 * Westwood Studios AUD Format Demuxer
3 * Copyright (c) 2003 The ffmpeg Project
5 * This file is part of FFmpeg.
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.
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.
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
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/intreadwrite.h"
40 #define AUD_HEADER_SIZE 12
41 #define AUD_CHUNK_PREAMBLE_SIZE 8
42 #define AUD_CHUNK_SIGNATURE 0x0000DEAF
44 static int wsaud_probe(AVProbeData *p)
48 /* Probabilistic content detection strategy: There is no file signature
49 * so perform sanity checks on various header parameters:
50 * 8000 <= sample rate (16 bits) <= 48000 ==> 40001 acceptable numbers
51 * flags <= 0x03 (2 LSBs are used) ==> 4 acceptable numbers
52 * compression type (8 bits) = 1 or 99 ==> 2 acceptable numbers
53 * first audio chunk signature (32 bits) ==> 1 acceptable number
54 * The number space contains 2^64 numbers. There are 40001 * 4 * 2 * 1 =
55 * 320008 acceptable number combinations.
58 if (p->buf_size < AUD_HEADER_SIZE + AUD_CHUNK_PREAMBLE_SIZE)
61 /* check sample rate */
62 field = AV_RL16(&p->buf[0]);
63 if ((field < 8000) || (field > 48000))
66 /* enforce the rule that the top 6 bits of this flags field are reserved (0);
67 * this might not be true, but enforce it until deemed unnecessary */
68 if (p->buf[10] & 0xFC)
71 /* note: only check for WS IMA (type 99) right now since there is no
72 * support for type 1 */
73 if (p->buf[11] != 99 && p->buf[11] != 1)
76 /* read ahead to the first audio chunk and validate the first header signature */
77 if (AV_RL32(&p->buf[16]) != AUD_CHUNK_SIGNATURE)
80 /* return 1/2 certainty since this file check is a little sketchy */
81 return AVPROBE_SCORE_MAX / 2;
84 static int wsaud_read_header(AVFormatContext *s)
86 AVIOContext *pb = s->pb;
88 unsigned char header[AUD_HEADER_SIZE];
89 int sample_rate, channels, codec;
91 if (avio_read(pb, header, AUD_HEADER_SIZE) != AUD_HEADER_SIZE)
94 sample_rate = AV_RL16(&header[0]);
95 channels = (header[10] & 0x1) + 1;
98 /* initialize the audio decoder stream */
99 st = avformat_new_stream(s, NULL);
101 return AVERROR(ENOMEM);
106 av_log_ask_for_sample(s, "Stereo WS-SND1 is not supported.\n");
107 return AVERROR_PATCHWELCOME;
109 st->codec->codec_id = CODEC_ID_WESTWOOD_SND1;
112 st->codec->codec_id = CODEC_ID_ADPCM_IMA_WS;
113 st->codec->bits_per_coded_sample = 4;
114 st->codec->bit_rate = channels * sample_rate * 4;
117 av_log_ask_for_sample(s, "Unknown codec: %d\n", codec);
118 return AVERROR_PATCHWELCOME;
120 avpriv_set_pts_info(st, 64, 1, sample_rate);
121 st->codec->codec_type = AVMEDIA_TYPE_AUDIO;
122 st->codec->channels = channels;
123 st->codec->sample_rate = sample_rate;
128 static int wsaud_read_packet(AVFormatContext *s,
131 AVIOContext *pb = s->pb;
132 unsigned char preamble[AUD_CHUNK_PREAMBLE_SIZE];
133 unsigned int chunk_size;
135 AVStream *st = s->streams[0];
137 if (avio_read(pb, preamble, AUD_CHUNK_PREAMBLE_SIZE) !=
138 AUD_CHUNK_PREAMBLE_SIZE)
141 /* validate the chunk */
142 if (AV_RL32(&preamble[4]) != AUD_CHUNK_SIGNATURE)
143 return AVERROR_INVALIDDATA;
145 chunk_size = AV_RL16(&preamble[0]);
147 if (st->codec->codec_id == CODEC_ID_WESTWOOD_SND1) {
148 /* For Westwood SND1 audio we need to add the output size and input
149 size to the start of the packet to match what is in VQA.
150 Specifically, this is needed to signal when a packet should be
151 decoding as raw 8-bit pcm or variable-size ADPCM. */
152 int out_size = AV_RL16(&preamble[2]);
153 if ((ret = av_new_packet(pkt, chunk_size + 4)))
155 if ((ret = avio_read(pb, &pkt->data[4], chunk_size)) != chunk_size)
156 return ret < 0 ? ret : AVERROR(EIO);
157 AV_WL16(&pkt->data[0], out_size);
158 AV_WL16(&pkt->data[2], chunk_size);
160 pkt->duration = out_size;
162 ret = av_get_packet(pb, pkt, chunk_size);
163 if (ret != chunk_size)
166 /* 2 samples/byte, 1 or 2 samples per frame depending on stereo */
167 pkt->duration = (chunk_size * 2) / st->codec->channels;
169 pkt->stream_index = st->index;
174 AVInputFormat ff_wsaud_demuxer = {
176 .long_name = NULL_IF_CONFIG_SMALL("Westwood Studios audio format"),
177 .read_probe = wsaud_probe,
178 .read_header = wsaud_read_header,
179 .read_packet = wsaud_read_packet,