[wdmaudiodev] Re: How to adjust lip-sync for WaveCyclic driver using GetPosition()
- From: "Philip Gruebele" <pgruebele@xxxxxxx>
- To: <wdmaudiodev@xxxxxxxxxxxxx>
- Date: Sat, 8 Jun 2013 12:42:58 -0400
Hi Tim.
60ms is a bit high and I will decrease this, but under some circumstances it
can be necessary to buffer audio - e.g. networked audio, downstream clocks, etc.
I will try to reduce this. But it's a shame that there is no method of
properly dealing with latency from within the driver :( This seems to be a
rather fundamental oversight.
Cheers
Philip
-----Original Message-----
From: wdmaudiodev-bounce@xxxxxxxxxxxxx
[mailto:wdmaudiodev-bounce@xxxxxxxxxxxxx] On Behalf Of Tim Roberts
Sent: Friday, June 07, 2013 7:45 PM
To: wdmaudiodev@xxxxxxxxxxxxx
Subject: [wdmaudiodev] Re: How to adjust lip-sync for WaveCyclic driver using
GetPosition()
Philip Gruebele wrote:
> According to MS docs, GetPosition() should start incrementing when in
> the RUN state. ... this means that after entering KS_RUN state,
> GetPosition() should return 0 for about 60ms, and only then start to
> increment (since the hardware is not outputting the sample data for
> the first 60 ms).
GetPosition needs to increase always, so I think you will have to have it start
at -60ms.
However, I'm not convinced this will help lip synch. Applications usually do
not do their audio/video syncing based on the absolute value of the time.
Instead, they use relative time from the first sample.
For that, you could start GetPosition at 30 minutes and it wouldn't make a
difference.
60ms is a LOT of latency. Why is it so high?
--
Tim Roberts, timr@xxxxxxxxx
Providenza & Boekelheide, Inc.
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