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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 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 | ||
36 | #include "libavutil/channel_layout.h" | |
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 | ||
59 | if (p->buf_size < AUD_HEADER_SIZE + AUD_CHUNK_PREAMBLE_SIZE) | |
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 */ | |
80 | return AVPROBE_SCORE_EXTENSION; | |
81 | } | |
82 | ||
83 | static int wsaud_read_header(AVFormatContext *s) | |
84 | { | |
85 | AVIOContext *pb = s->pb; | |
86 | AVStream *st; | |
87 | unsigned char header[AUD_HEADER_SIZE]; | |
88 | int sample_rate, channels, codec; | |
89 | ||
90 | if (avio_read(pb, header, AUD_HEADER_SIZE) != AUD_HEADER_SIZE) | |
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 | } | |
108 | st->codec->codec_id = AV_CODEC_ID_WESTWOOD_SND1; | |
109 | break; | |
110 | case 99: | |
111 | st->codec->codec_id = AV_CODEC_ID_ADPCM_IMA_WS; | |
112 | st->codec->bits_per_coded_sample = 4; | |
113 | st->codec->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); | |
120 | st->codec->codec_type = AVMEDIA_TYPE_AUDIO; | |
121 | st->codec->channels = channels; | |
122 | st->codec->channel_layout = channels == 1 ? AV_CH_LAYOUT_MONO : | |
123 | AV_CH_LAYOUT_STEREO; | |
124 | st->codec->sample_rate = sample_rate; | |
125 | ||
126 | return 0; | |
127 | } | |
128 | ||
129 | static int wsaud_read_packet(AVFormatContext *s, | |
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) != | |
139 | 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 | ||
148 | if (st->codec->codec_id == AV_CODEC_ID_WESTWOOD_SND1) { | |
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))) | |
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 | /* 2 samples/byte, 1 or 2 samples per frame depending on stereo */ | |
168 | pkt->duration = (chunk_size * 2) / st->codec->channels; | |
169 | } | |
170 | pkt->stream_index = st->index; | |
171 | ||
172 | return ret; | |
173 | } | |
174 | ||
175 | AVInputFormat ff_wsaud_demuxer = { | |
176 | .name = "wsaud", | |
177 | .long_name = NULL_IF_CONFIG_SMALL("Westwood Studios audio"), | |
178 | .read_probe = wsaud_probe, | |
179 | .read_header = wsaud_read_header, | |
180 | .read_packet = wsaud_read_packet, | |
181 | }; |