Bad sound quality ("wow and flutter" - "leiern" in German)

[Pio2001]

Thanks for the clarification.

[Rémi Denis-Courmont]

I don't think the issue is OS version related. The same audio APIs are used with all Windows versions.

I wouldn't be so sure. It's obviously hardware-dependent. And thus it is very likely linked to driver bugs. And drivers do depend on OS versions.

[davros]

So 4 years later - and I've STILL got this problem with VLC. Pitch just slowly drifts up and down. I've changed PC's and operating systems several times since my last post. How is it this problem still exists....?

[Pio2001]

As Rémi Denis-Courmont said above, this is unavoidable for a TV Receiver. A colleague told me that it was mandatory in the specifications of video streaming.

The question is why not turn it off while playing video files, and enabling it only when VLC is playing a real-time stream ?

Another idea : reading a local file, what data does VLC rely on in order to trigger the speed change ?? If we set them to zero or null or whatever (since NO streaming is occuring), there won't be any speed change during playback.
Pros : should be easily realized.
Cons : the resampler is running for nothing, unusefully altering audio data.

[Rémi Denis-Courmont]

No clock is perfect. Some are worst than others. The system clock will always drift ever slightly from the audio sampling clock and from the video vertical synchronization clock. Resampling is unavoidable.

For non-live content, it is theoretically possible to use either the audio or the video clock as reference. But the other clock will still drift, so there will anyway be lost/duplicates pictures or resampling. Regardless, adding this feature to VLC is a vast effort that nobody volunteered for.

[Pio2001]

No clock is perfect. Some are worst than others. The system clock will always drift ever slightly from the audio sampling clock and from the video vertical synchronization clock. Resampling is unavoidable.

I see. I was only thinking about the distant clock, but I forgot about the two local clocks.
I agree. As long as an independant soundcard is used for playback, resampling is unavoidable (things change with the use of HDMI, that carries both video and sound at the same clock).

I just performed a spectral analysis of two recordings of the same flv file, played back by Youtube integrated flash player, then by VLC. The maximum pitch difference between the two is 1.7 %.