C'est fou le format wav, le chunck "fmt " a plusieurs champs qui... ne servent vraiment a rien :

Average Bytes Per Second
This value indicates how many bytes of wave data must be streamed to a D/A converter per second in order to play the wave file. This information is useful when determining if data can be streamed from the source fast enough to keep up with playback. This value can be easily calculated with the formula:
AvgBytesPerSec = SampleRate * BlockAlign

Block Align
BlockAlign = SignificantBitsPerSample / 8 * NumChannels