[mythtv-users] Video is behind audio, dropping frames to catch up (VDPAU, HD content)

[Richard]

On 12/03/13 18:49, Thomas Börkel wrote:
> HI!
>
> I finally fixed this problem!
>
> For the archive: It was the Soundblaster Live X PCI sound card!
>
> I've had this problem now for several years. It happened every now and
> then (1-2 times per recording), but after switching from 0.23.1 to 0.26
> and from SD to HD, it happened more often, like every 5 minutes sometimes.
>
> After trying everything I could think of in terms of software, I finally
> looked at the hardware. I switched from the PCI card to onboard audio
> and the problem was gone.
>
> The reason I had stayed with the PCI card for so long are:
>
> 1. Not every board has digital audio out. My new one luckily has.
> 2. I could use analog and digital audio with one ALSA device ("default").
>
> Now, after the problem being fixed, I still don't understand the real
> cause behind it:
>
> 1. Bug of the card?
> 2. Bug of the driver of the card?
> 3. Bug of MythTV?
>
> And why was it also triggered by MythTV trying to connect to the crashed
> MythLCDserver?
>
> Would be interesting to know, although I am really glad this is fixed now!

Hi Thomas,

I'm no audio expert but maybe the audio buffers were set too low on the 
PCI card?

Do you see anything like the following in your frontend logs?

ALSA: Try to manually increase audio buffer with...

Interestingly, if I select 'ALSA:default', I don't see that message but 
if the buffers are set too low, playback stutters terribly and I see the 
same error message you originally reported.

If I select something else like 'ALSA:dmix:CARD=PCH,DEV=0', I get the 
'Try to manually increase...' message but playback seems fine regardless 
of what size I set the buffers to.

Both settings select the same (and only) sound card so I don't know 
exactly what's going on but maybe you have a similar issue.

Richard.