[mythtv-users] Airplay Sync with Multiple Devices - Mythtv only one out of sync

[Jean-Yves Avenard]

On 19 December 2012 16:23, Bob H. <bob.havlin at gmail.com> wrote:
> I was hoping someone might have an idea of how to fix a sync issue that
> occurs when airplay-ing to my frontend.
> I am playing from itunes on a Windows-7 (x64) box to a laptop frontend
> (32-bit mythbuntu) and an airport speakers.
> The Win-7 and airport speaks stay in sync perfectly, but the mythtv-frontend
> lags and this gets worse the longer playback continues.

Unfortunately, there's very little we can do here.

Apple has the privilege of dealing with two different hardware only,
controlling the entire toolchain.

Myth on the other hand, need to do with different platforms (BSD, OS
X, Windows, Linux), different audio framework for each OS (linux alone
has over 4 that we support). Measuring the latency relies on those
audio framework to provide accurate data.

All I can say is this:
on my system, using ALSA, sync is perfect between all my system.

I have to admit that I only work as hard as I could to get my system
in sync. And to my defence, that's more than anyone did because none
of the other AirPlay implementation (other than apple) actually care
about audio latencies, they just play the audio as soon as they
receive it.

In your log, you have buffer underruns, increase the ALSA audio buffer
as probably mentioned in the log if you run mythfrontend with -v
audio.
audio buffer underruns will keen your latency and throws off any
calculations performed.

JY