[alsa-devel] Improving status timestamp accuracy

[Takashi Iwai]

On Sun, 05 Jun 2016 12:33:20 +0200,
Alan Young wrote:
> 
> Regardless of what value of DMA_RESIDUE_GRANULARITY_xxx that a driver
> claims to support, it is not really defined how fine a burst might
> be. So the end result is, from the point of view of audio, that the
> resulting position obtained by the pointer() call is pretty
> inaccurate. Hence my proposal to attempt to improve the accuracy of
> the pcm_status() result given the above constraints.

Well, the subject appears misleading.  What you want isn't the audio
timestamp accuracy.  From API POV, the accurate position is calculated
via the (additional) delay.  So, what you want is rather the accurate
position delay accounting, and the audio timestamp is merely one of
the ways to achieve that.


Takashi