[mythtv-users] Bob deinterlacing drops frames, but not high CPU

[Doug Larrick]

Matt Doran wrote:
> It's 25fps DVB broadcast (I'm in australia).  I've got my X vertical 
> refresh is 50Hz, because I was under the impression this should lead to 
> smoother scrolling (i.e. an integer multiple of the frame rate).
> 
> Is that what you were after?

Yup.  You've got that set up right.

> Another thing that may or may not be useful.  I'm not using the OpenGL 
> sync method, because when I enable it, I get a very subtle mismatch 
> between audio and video ... and no frame drop messages.  So I'm using 
> the RTC video timing.  

I think this is your problem.  RTC calculates when the next frame should
show up, but has no feedback from the video display.  So occasionally
the video card waits an extra frame (or plays too early)... when enough
of these add up, we skip a tooth and you get your message.

Also look for the message "Refresh rate: xxx, frame interval: yyy"
(which is under --verbose general or playback, not sure which) to see if
Myth's estimation of your refresh rate is what you're expecting (note
that this is interval in usec, not frequency in Hz).

You know there's an adjustment for audio/video sync, right?  During
playback hit "menu" and it's listed in the OSD menu.  There may be a
direct keybinding too; not sure.

It's also possible your soundcard is the culprit if its timing is off.
Try enabling extra buffering if it's not already; if you have a spare
soundcard lying around you might try that as well.  Or try "use video as
timebase" (unless you're using AC3 or DTS passthru, which is incompatible).

-Doug

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