I dunno about this exactly, but with audio applications if you have for example a samplerate set to 44100hz and you're playing back audio with a samplerate of 22050hz, it will play back half the speed.
for example when working with a music application and the driver is set at 96khz samplerate and you manage to play back a 44.1khz MP3 in another application at the same time, it will play back faster.
my point is I would guess it has something to do with different bitrates/samplerates in different streams.
that's all
