This is the description of the regular WAVE file format. It is nothing special to GTA1.
Offset Size Name Description
------------------------------------------------------------------------------------
The canonical WAVE format starts with the RIFF header:
0 4 ChunkID Contains the letters "RIFF" in ASCII form
(0x52494646 big-endian form).
4 4 ChunkSize 36 + SubChunk2Size, or more precisely:
4 + (8 + SubChunk1Size) + (8 + SubChunk2Size)
This is the size of the rest of the chunk
following this number. This is the size of the
entire file in bytes minus 8 bytes for the
two fields not included in this count:
ChunkID and ChunkSize.
8 4 Format Contains the letters "WAVE"
(0x57415645 big-endian form).
The "WAVE" format consists of two subchunks: "fmt " and "data":
The "fmt " subchunk describes the sound data's format:
12 4 Subchunk1ID Contains the letters "fmt "
(0x666d7420 big-endian form).
16 4 Subchunk1Size 16 for PCM. This is the size of the
rest of the Subchunk which follows this number.
20 2 AudioFormat PCM = 1 (i.e. Linear quantization)
Values other than 1 indicate some
form of compression.
22 2 NumChannels Mono = 1, Stereo = 2, etc.
24 4 SampleRate 8000, 44100, etc.
28 4 ByteRate == SampleRate * NumChannels * BitsPerSample/8
32 2 BlockAlign == NumChannels * BitsPerSample/8
The number of bytes for one sample including
all channels. I wonder what happens when
this number isn't an integer?
34 2 BitsPerSample 8 bits = 8, 16 bits = 16, etc.
2 ExtraParamSize if PCM, then doesn't exist
X ExtraParams space for extra parameters
The "data" subchunk contains the size of the data and the actual sound:
36 4 Subchunk2ID Contains the letters "data"
(0x64617461 big-endian form).
40 4 Subchunk2Size == NumSamples * NumChannels * BitsPerSample/8
This is the number of bytes in the data.
You can also think of this as the size
of the read of the subchunk following this
number.
44 * Data The actual sound data.
<?php
$files = glob(__DIR__ . '/*.wav');
foreach ($files as $file) {
$handle = fopen($file, 'rb');
if (!$handle) {
echo "Cannot
open file: $file\n";
continue;
}
// Read
RIFF Header
$header = fread($handle, 44);
fclose($handle);
if (strlen($header) < 44) {
echo "Invalid
WAV file: $file\n";
continue;
}
// Split
Header
$data = unpack(
'a4chunkID/' . // "RIFF"
'VchunkSize/' .
'a4format/' . // "WAVE"
'a4subchunk1ID/' . // "fmt "
'Vsubchunk1Size/' .
'vaudioFormat/' .
'vnumChannels/' .
'VsampleRate/' .
'VbyteRate/' .
'vblockAlign/' .
'vbitsPerSample',
$header
);
// Check
format
$format = match ($data['audioFormat']) {
1 => 'PCM',
default => 'Unknown (' . $data['audioFormat'] . ')'
};
// Format
output
$channels = $data['numChannels'] === 1 ? '1 channel' : $data['numChannels'] . ' channels';
$sampleRate = number_format($data['sampleRate'] / 1000, 3, '.', '') . 'kHz';
$bits = $data['bitsPerSample'] . ' bit';
echo basename($file) . ": RIFF Wave, $format format, $channels, $sampleRate, $bits\n";
}