[mythtv-users] Frames per second?

[Ray Olszewski]

At 03:32 PM 4/21/2003 -0400, jeff at burstable.net wrote:
>It doesnt appear to be 'torn'.  The best I can describe it would be if
>playing a PC game on a underpowered pc and the FPS drop under 20 fps or
>so.  Typical CPU usage is about 60% - 70% when watching live tv.  Oh and
>the deinterlace filter is one.

It is always hard to be certain from these sorts of descriptions (the one 
above and your earlier one), but what you describe sounds like the capture 
process is dropping frames for some reason. The usual one is that the image 
is sufficiently rich in complexity that the encoder can't work fast enough 
on one frame before it has to get the next one, so some are lost. In this 
context, "complexity" is anything that makes encoding harder to do, 
including simple noise (I get a 50% drop rate in frames when there is 
nothing connected to the Television input, for example).

Panning motion is a good way to introduce this sort of complexity ... I 
don't tape sporting events, but I've seen similar sorts of problems in The 
Simpsons, at the beginning where the "camera" (the animation PoV) pans over 
the field full of supporting characters, or a bit earlier where sometimes 
it pans and zooms to the school for a Bart Blackboard Quote.

If I'm right, I think your only options are (A) get a faster computer or 
(B) reduce the pixel size of the capture.

Oh, one thing you should check: when you load the bttv module, are you 
including a suitable gbuffers= argument? (I usually use gbuffers=32 with my 
non-Myth systems, and I expect I'll do the same when I finally get Myth 
running here. If MythTV doesn't work the way I'm assuming here, I hope 
someone will correct me.) This can help buffer against brief bursts of 
complexity in the frame sequence.