#include <disorder.h>
#include "madshim.h"
+#include "wav.h"
static void *mmap_file(const char *path, size_t *lengthp) {
int fd;
}
static long tl_wav(const char *path) {
- size_t length;
- void *base;
- long duration = -1;
- unsigned char *ptr;
- unsigned n, m, data_bytes = 0, samples_per_second = 0;
- unsigned n_channels = 0, bits_per_sample = 0, sample_point_size;
- unsigned sample_frame_size, n_samples;
+ struct wavfile f[1];
+ int err, sample_frame_size;
+ long duration;
- /* 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.
- *
- * Given all of the above all we need to do is pick up some numbers from the
- * format chunk, and the length of the data chunk, and do some arithmetic.
- */
- if(!(base = mmap_file(path, &length))) return -1;
-#define get16(p) ((p)[0] + 256 * (p)[1])
-#define get32(p) ((p)[0] + 256 * ((p)[1] + 256 * ((p)[2] + 256 * (p)[3])))
- ptr = base;
- if(length < 12) goto out;
- if(strncmp((char *)ptr, "RIFF", 4)) goto out; /* wrong type */
- n = get32(ptr + 4); /* file length */
- if(n > length - 8) goto out; /* truncated */
- ptr += 8; /* skip file header */
- if(n < 4 || strncmp((char *)ptr, "WAVE", 4)) goto out; /* wrong type */
- ptr += 4; /* skip 'WAVE' */
- n -= 4;
- while(n >= 8) {
- m = get32(ptr + 4); /* chunk length */
- if(m > n - 8) goto out; /* truncated */
- if(!strncmp((char *)ptr, "fmt ", 4)) {
- if(samples_per_second) goto out; /* duplicate format chunk! */
- n_channels = get16(ptr + 0x0a);
- samples_per_second = get32(ptr + 0x0c);
- bits_per_sample = get16(ptr + 0x16);
- if(!samples_per_second) goto out; /* bogus! */
- } else if(!strncmp((char *)ptr, "data", 4)) {
- if(data_bytes) goto out; /* multiple data chunks! */
- data_bytes = m; /* remember data size */
- }
- m += 8; /* include chunk header */
- ptr += m; /* skip chunk */
- n -= m;
+ if((err = wav_init(f, path))) {
+ disorder_error(err, "error opening %s", path);
+ return -1;
}
- sample_point_size = (bits_per_sample + 7) / 8;
- sample_frame_size = sample_point_size * n_channels;
- if(!sample_frame_size) goto out; /* bogus or overflow */
- n_samples = data_bytes / sample_frame_size;
- duration = (n_samples + samples_per_second - 1) / samples_per_second;
-out:
- munmap(base, length);
+ sample_frame_size = (f->bits + 7) / 8 * f->channels;
+ if(sample_frame_size) {
+ const long long n_samples = f->datasize / sample_frame_size;
+ duration = (n_samples + f->rate - 1) / f->rate;
+ } else
+ duration = -1;
+ wav_destroy(f);
return duration;
}
~mdw / disorder / blobdiff