--- /dev/null
+/*
+ * This file is part of DisOrder
+ * Copyright (C) 2007 Richard Kettlewell
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program. If not, see <http://www.gnu.org/licenses/>.
+ */
+/** @file lib/wav.c
+ * @brief WAV file support
+ *
+ * This is used by the WAV file suppoort in the tracklength plugin and
+ * by disorder-decode (see @ref server/decode.c).
+ */
+
+/* Sources:
+ *
+ * http://www.technology.niagarac.on.ca/courses/comp530/WavFileFormat.html
+ * http://www.borg.com/~jglatt/tech/wave.htm
+ * http://www.borg.com/~jglatt/tech/aboutiff.htm
+ *
+ * These files consists of a header followed by chunks.
+ * Multibyte values are little-endian.
+ *
+ * 12 byte file header:
+ * offset size meaning
+ * 00 4 'RIFF'
+ * 04 4 length of rest of file
+ * 08 4 'WAVE'
+ *
+ * The length includes 'WAVE' but excludes the 1st 8 bytes.
+ *
+ * Chunk header:
+ * 00 4 chunk ID
+ * 04 4 length of rest of chunk
+ *
+ * The stated length may be odd, if so then there is an implicit padding byte
+ * appended to the chunk to make it up to an even length (someone wasn't
+ * think about 32/64-bit worlds).
+ *
+ * Also some files seem to have extra stuff at the end of chunks that nobody
+ * I know of documents. Go figure, but check the length field rather than
+ * deducing the length from the ID.
+ *
+ * Format chunk:
+ * 00 4 'fmt'
+ * 04 4 length of rest of chunk
+ * 08 2 compression (1 = none)
+ * 0a 2 number of channels
+ * 0c 4 samples/second
+ * 10 4 average bytes/second, = (samples/sec) * (bytes/sample)
+ * 14 2 bytes/sample
+ * 16 2 bits/sample point
+ *
+ * 'sample' means 'sample frame' above, i.e. a sample point for each channel.
+ *
+ * Data chunk:
+ * 00 4 'data'
+ * 04 4 length of rest of chunk
+ * 08 ... data
+ *
+ * There is only allowed to be one data chunk. Some people violate this; we
+ * shall encourage people to fix their broken WAV files by not supporting
+ * this violation and because it's easier.
+ *
+ * As to the encoding of the data:
+ *
+ * Firstly, samples up to 8 bits in size are unsigned, larger samples are
+ * signed. Madness.
+ *
+ * Secondly sample points are stored rounded up to a multiple of 8 bits in
+ * size. Marginally saner.
+ *
+ * Written as a single word (of 8, 16, 24, whatever bits) the padding to
+ * implement this happens at the right hand (least significant) end.
+ * e.g. assuming a 9 bit sample:
+ *
+ * | padded sample word |
+ * | 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0 |
+ * | 8 7 6 5 4 3 2 1 0 - - - - - - - |
+ *
+ * But this is a little-endian file format so the least significant byte is
+ * the first, which means that the padding is "between" the bits if you
+ * imagine them in their usual order:
+ *
+ * | first byte | second byte |
+ * | 7 6 5 4 3 2 1 0 | 7 6 5 4 3 2 1 0 |
+ * | 0 - - - - - - - | 8 7 6 5 4 3 2 1 |
+ *
+ * Sample points are grouped into sample frames, consisting of as many
+ * samples points as their are channels. It seems that there are standard
+ * orderings of different channels.
+ */
+
+#include "common.h"
+
+#include <unistd.h>
+#include <fcntl.h>
+#include <errno.h>
+
+#include "log.h"
+#include "wav.h"
+
+static inline uint16_t get16(const char *ptr) {
+ return (uint8_t)ptr[0] + 256 * (uint8_t)ptr[1];
+}
+
+static inline uint32_t get32(const char *ptr) {
+ return (uint8_t)ptr[0] + 256 * (uint8_t)ptr[1]
+ + 65536 * (uint8_t)ptr[2] + 16777216 * (uint8_t)ptr[3];
+}
+
+/** @brief Open a WAV file
+ * @return 0 on success, an errno value on error
+ */
+int wav_init(struct wavfile *f, const char *path) {
+ int err, n;
+ char header[64];
+ off_t where;
+
+ memset(f, 0, sizeof *f);
+ f->data = -1;
+ if(hreader_init(path, f->input)) goto error_errno;
+ /* Read the file header
+ *
+ * offset size meaning
+ * 00 4 'RIFF'
+ * 04 4 length of rest of file
+ * 08 4 'WAVE'
+ * */
+ if((n = hreader_pread(f->input, header, 12, 0)) < 0) goto error_errno;
+ else if(n < 12) goto einval;
+ if(strncmp(header, "RIFF", 4) || strncmp(header + 8, "WAVE", 4))
+ goto einval;
+ f->length = 8 + get32(header + 4);
+ /* Visit all the chunks */
+ for(where = 12; where + 8 <= f->length;) {
+ /* Read the chunk header
+ *
+ * offset size meaning
+ * 00 4 chunk ID
+ * 04 4 length of rest of chunk
+ */
+ if((n = hreader_pread(f->input, header, 8, where)) < 0) goto error_errno;
+ else if(n < 8) goto einval;
+ if(!strncmp(header,"fmt ", 4)) {
+ /* This is the format chunk
+ *
+ * offset size meaning
+ * 00 4 'fmt'
+ * 04 4 length of rest of chunk
+ * 08 2 compression (1 = none)
+ * 0a 2 number of channels
+ * 0c 4 samples/second
+ * 10 4 average bytes/second, = (samples/sec) * (bytes/sample)
+ * 14 2 bytes/sample
+ * 16 2 bits/sample point
+ * 18 ? extra undocumented rubbish
+ */
+ if(get32(header + 4) < 16) goto einval;
+ if((n = hreader_pread(f->input, header + 8, 16, where + 8)) < 0)
+ goto error_errno;
+ else if(n < 16) goto einval;
+ f->channels = get16(header + 0x0A);
+ f->rate = get32(header + 0x0C);
+ f->bits = get16(header + 0x16);
+ } else if(!strncmp(header, "data", 4)) {
+ /* Remember where the data chunk was and how big it is */
+ f->data = where;
+ f->datasize = get32(header + 4);
+ }
+ where += 8 + get32(header + 4);
+ }
+ /* There had better have been a format chunk */
+ if(f->rate == 0) goto einval;
+ /* There had better have been a data chunk */
+ if(f->data == -1) goto einval;
+ return 0;
+einval:
+ err = EINVAL;
+ goto error;
+error_errno:
+ err = errno;
+error:
+ wav_destroy(f);
+ return err;
+}
+
+/** @brief Close a WAV file */
+void wav_destroy(struct wavfile *f) {
+ hreader_close(f->input);
+}
+
+/** @brief Visit all the data in a WAV file
+ * @param f WAV file handle
+ * @param callback Called for successive blocks of data
+ * @param u User data
+ *
+ * @p callback will only ever be passed whole frames.
+ */
+int wav_data(struct wavfile *f,
+ wav_data_callback *callback,
+ void *u) {
+ off_t left = f->datasize;
+ off_t where = f->data + 8;
+ char buffer[4096];
+ int err;
+ ssize_t n;
+ const size_t bytes_per_frame = f->channels * ((f->bits + 7) / 8);
+
+ while(left > 0) {
+ size_t want = (off_t)sizeof buffer > left ? (size_t)left : sizeof buffer;
+
+ want -= want % bytes_per_frame;
+ if((n = hreader_pread(f->input, buffer, want, where)) < 0) return errno;
+ if((size_t)n < want) return EINVAL;
+ if((err = callback(f, buffer, n, u))) return err;
+ where += n;
+ left -= n;
+ }
+ return 0;
+}
+
+/*
+Local Variables:
+c-basic-offset:2
+comment-column:40
+fill-column:79
+indent-tabs-mode:nil
+End:
+*/
~mdw / disorder / blobdiff