| 1 | /* |
| 2 | * This file is part of DisOrder |
| 3 | * Copyright (C) 2007 Richard Kettlewell |
| 4 | * |
| 5 | * This program is free software; you can redistribute it and/or modify |
| 6 | * it under the terms of the GNU General Public License as published by |
| 7 | * the Free Software Foundation; either version 2 of the License, or |
| 8 | * (at your option) any later version. |
| 9 | * |
| 10 | * This program is distributed in the hope that it will be useful, but |
| 11 | * WITHOUT ANY WARRANTY; without even the implied warranty of |
| 12 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU |
| 13 | * General Public License for more details. |
| 14 | * |
| 15 | * You should have received a copy of the GNU General Public License |
| 16 | * along with this program; if not, write to the Free Software |
| 17 | * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 |
| 18 | * USA |
| 19 | */ |
| 20 | /** @file lib/wav.c |
| 21 | * @brief WAV file support |
| 22 | * |
| 23 | * This is used by the WAV file suppoort in the tracklength plugin and |
| 24 | * by disorder-decode (see @ref server/decode.c). |
| 25 | */ |
| 26 | |
| 27 | /* Sources: |
| 28 | * |
| 29 | * http://www.technology.niagarac.on.ca/courses/comp530/WavFileFormat.html |
| 30 | * http://www.borg.com/~jglatt/tech/wave.htm |
| 31 | * http://www.borg.com/~jglatt/tech/aboutiff.htm |
| 32 | * |
| 33 | * These files consists of a header followed by chunks. |
| 34 | * Multibyte values are little-endian. |
| 35 | * |
| 36 | * 12 byte file header: |
| 37 | * offset size meaning |
| 38 | * 00 4 'RIFF' |
| 39 | * 04 4 length of rest of file |
| 40 | * 08 4 'WAVE' |
| 41 | * |
| 42 | * The length includes 'WAVE' but excludes the 1st 8 bytes. |
| 43 | * |
| 44 | * Chunk header: |
| 45 | * 00 4 chunk ID |
| 46 | * 04 4 length of rest of chunk |
| 47 | * |
| 48 | * The stated length may be odd, if so then there is an implicit padding byte |
| 49 | * appended to the chunk to make it up to an even length (someone wasn't |
| 50 | * think about 32/64-bit worlds). |
| 51 | * |
| 52 | * Also some files seem to have extra stuff at the end of chunks that nobody |
| 53 | * I know of documents. Go figure, but check the length field rather than |
| 54 | * deducing the length from the ID. |
| 55 | * |
| 56 | * Format chunk: |
| 57 | * 00 4 'fmt' |
| 58 | * 04 4 length of rest of chunk |
| 59 | * 08 2 compression (1 = none) |
| 60 | * 0a 2 number of channels |
| 61 | * 0c 4 samples/second |
| 62 | * 10 4 average bytes/second, = (samples/sec) * (bytes/sample) |
| 63 | * 14 2 bytes/sample |
| 64 | * 16 2 bits/sample point |
| 65 | * |
| 66 | * 'sample' means 'sample frame' above, i.e. a sample point for each channel. |
| 67 | * |
| 68 | * Data chunk: |
| 69 | * 00 4 'data' |
| 70 | * 04 4 length of rest of chunk |
| 71 | * 08 ... data |
| 72 | * |
| 73 | * There is only allowed to be one data chunk. Some people violate this; we |
| 74 | * shall encourage people to fix their broken WAV files by not supporting |
| 75 | * this violation and because it's easier. |
| 76 | * |
| 77 | * As to the encoding of the data: |
| 78 | * |
| 79 | * Firstly, samples up to 8 bits in size are unsigned, larger samples are |
| 80 | * signed. Madness. |
| 81 | * |
| 82 | * Secondly sample points are stored rounded up to a multiple of 8 bits in |
| 83 | * size. Marginally saner. |
| 84 | * |
| 85 | * Written as a single word (of 8, 16, 24, whatever bits) the padding to |
| 86 | * implement this happens at the right hand (least significant) end. |
| 87 | * e.g. assuming a 9 bit sample: |
| 88 | * |
| 89 | * | padded sample word | |
| 90 | * | 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0 | |
| 91 | * | 8 7 6 5 4 3 2 1 0 - - - - - - - | |
| 92 | * |
| 93 | * But this is a little-endian file format so the least significant byte is |
| 94 | * the first, which means that the padding is "between" the bits if you |
| 95 | * imagine them in their usual order: |
| 96 | * |
| 97 | * | first byte | second byte | |
| 98 | * | 7 6 5 4 3 2 1 0 | 7 6 5 4 3 2 1 0 | |
| 99 | * | 0 - - - - - - - | 8 7 6 5 4 3 2 1 | |
| 100 | * |
| 101 | * Sample points are grouped into sample frames, consisting of as many |
| 102 | * samples points as their are channels. It seems that there are standard |
| 103 | * orderings of different channels. |
| 104 | */ |
| 105 | |
| 106 | #include "common.h" |
| 107 | |
| 108 | #include <unistd.h> |
| 109 | #include <fcntl.h> |
| 110 | #include <errno.h> |
| 111 | |
| 112 | #include "log.h" |
| 113 | #include "wav.h" |
| 114 | |
| 115 | static inline uint16_t get16(const char *ptr) { |
| 116 | return (uint8_t)ptr[0] + 256 * (uint8_t)ptr[1]; |
| 117 | } |
| 118 | |
| 119 | static inline uint32_t get32(const char *ptr) { |
| 120 | return (uint8_t)ptr[0] + 256 * (uint8_t)ptr[1] |
| 121 | + 65536 * (uint8_t)ptr[2] + 16777216 * (uint8_t)ptr[3]; |
| 122 | } |
| 123 | |
| 124 | /** @brief Open a WAV file |
| 125 | * @return 0 on success, an errno value on error |
| 126 | */ |
| 127 | int wav_init(struct wavfile *f, const char *path) { |
| 128 | int err, n; |
| 129 | char header[64]; |
| 130 | off_t where; |
| 131 | |
| 132 | memset(f, 0, sizeof *f); |
| 133 | f->fd = -1; |
| 134 | f->data = -1; |
| 135 | if((f->fd = open(path, O_RDONLY)) < 0) goto error_errno; |
| 136 | /* Read the file header |
| 137 | * |
| 138 | * offset size meaning |
| 139 | * 00 4 'RIFF' |
| 140 | * 04 4 length of rest of file |
| 141 | * 08 4 'WAVE' |
| 142 | * */ |
| 143 | if((n = pread(f->fd, header, 12, 0)) < 0) goto error_errno; |
| 144 | else if(n < 12) goto einval; |
| 145 | if(strncmp(header, "RIFF", 4) || strncmp(header + 8, "WAVE", 4)) |
| 146 | goto einval; |
| 147 | f->length = 8 + get32(header + 4); |
| 148 | /* Visit all the chunks */ |
| 149 | for(where = 12; where + 8 <= f->length;) { |
| 150 | /* Read the chunk header |
| 151 | * |
| 152 | * offset size meaning |
| 153 | * 00 4 chunk ID |
| 154 | * 04 4 length of rest of chunk |
| 155 | */ |
| 156 | if((n = pread(f->fd, header, 8, where)) < 0) goto error_errno; |
| 157 | else if(n < 8) goto einval; |
| 158 | if(!strncmp(header,"fmt ", 4)) { |
| 159 | /* This is the format chunk |
| 160 | * |
| 161 | * offset size meaning |
| 162 | * 00 4 'fmt' |
| 163 | * 04 4 length of rest of chunk |
| 164 | * 08 2 compression (1 = none) |
| 165 | * 0a 2 number of channels |
| 166 | * 0c 4 samples/second |
| 167 | * 10 4 average bytes/second, = (samples/sec) * (bytes/sample) |
| 168 | * 14 2 bytes/sample |
| 169 | * 16 2 bits/sample point |
| 170 | * 18 ? extra undocumented rubbish |
| 171 | */ |
| 172 | if(get32(header + 4) < 16) goto einval; |
| 173 | if((n = pread(f->fd, header + 8, 16, where + 8)) < 0) goto error_errno; |
| 174 | else if(n < 16) goto einval; |
| 175 | f->channels = get16(header + 0x0A); |
| 176 | f->rate = get32(header + 0x0C); |
| 177 | f->bits = get16(header + 0x16); |
| 178 | } else if(!strncmp(header, "data", 4)) { |
| 179 | /* Remember where the data chunk was and how big it is */ |
| 180 | f->data = where; |
| 181 | f->datasize = get32(header + 4); |
| 182 | } |
| 183 | where += 8 + get32(header + 4); |
| 184 | } |
| 185 | /* There had better have been a format chunk */ |
| 186 | if(f->rate == 0) goto einval; |
| 187 | /* There had better have been a data chunk */ |
| 188 | if(f->data == -1) goto einval; |
| 189 | return 0; |
| 190 | einval: |
| 191 | err = EINVAL; |
| 192 | goto error; |
| 193 | error_errno: |
| 194 | err = errno; |
| 195 | error: |
| 196 | wav_destroy(f); |
| 197 | return err; |
| 198 | } |
| 199 | |
| 200 | /** @brief Close a WAV file */ |
| 201 | void wav_destroy(struct wavfile *f) { |
| 202 | if(f) { |
| 203 | const int save_errno = errno; |
| 204 | |
| 205 | if(f->fd >= 0) |
| 206 | close(f->fd); |
| 207 | errno = save_errno; |
| 208 | } |
| 209 | } |
| 210 | |
| 211 | /** @brief Visit all the data in a WAV file |
| 212 | * @param f WAV file handle |
| 213 | * @param callback Called for successive blocks of data |
| 214 | * @param u User data |
| 215 | * |
| 216 | * @p callback will only ever be passed whole frames. |
| 217 | */ |
| 218 | int wav_data(struct wavfile *f, |
| 219 | wav_data_callback *callback, |
| 220 | void *u) { |
| 221 | off_t left = f->datasize; |
| 222 | off_t where = f->data + 8; |
| 223 | char buffer[4096]; |
| 224 | int err; |
| 225 | ssize_t n; |
| 226 | const size_t bytes_per_frame = f->channels * ((f->bits + 7) / 8); |
| 227 | |
| 228 | while(left > 0) { |
| 229 | size_t want = (off_t)sizeof buffer > left ? (size_t)left : sizeof buffer; |
| 230 | |
| 231 | want -= want % bytes_per_frame; |
| 232 | if((n = pread(f->fd, buffer, want, where)) < 0) return errno; |
| 233 | if((size_t)n < want) return EINVAL; |
| 234 | if((err = callback(f, buffer, n, u))) return err; |
| 235 | where += n; |
| 236 | left -= n; |
| 237 | } |
| 238 | return 0; |
| 239 | } |
| 240 | |
| 241 | /* |
| 242 | Local Variables: |
| 243 | c-basic-offset:2 |
| 244 | comment-column:40 |
| 245 | fill-column:79 |
| 246 | indent-tabs-mode:nil |
| 247 | End: |
| 248 | */ |