[mythtv-users] overlay mode available?

Andreas Bohnert abo at online.de
Tue Nov 4 03:08:22 EST 2003


Joseph A. Caputo wrote:

>The likely reason that you're seeing frame drops has nothing to do with 
>'overlay' mode, but is more likely because you're pegging your CPU.  
>Xawtv has low resource requirements because it merely overlays/blits 
>the live video feed directly from the TV card to the display card.  It 
>doesn't have to encode or decode anything.  MythTV, however, is a true 
>PVR with timeshifting capabilities -- meaning when you're watching 
>LiveTV, what it's really doing is encoding the TV stream to disk 
>(RTjpeg, MPEG-4 or HW MPEG-2), then decoding it and playing the decoded 
>stream.  The decoded stream must be scaled for playback, i.e., if 
>you're recording at 640x480 but your display resolution is 800x600, the 
>video must be scaled up to 800x600.  This scaling is very CPU 
>intensive, but is supposed to be hardware-assisted by the Xv extensions 
>to XFree86 that work with your video card.
>  
>

ok, I see. thanks for your explanations!
I didn't realize that even when I just watch tv there is a encoding 
going on.
So I will have a look at the recording settings.
Your are right, my video card does not support Xv, that's why I will buy 
me a new one.

I have a PIII with 350 Mhz. my framegrapper card is a wintv togo.
I hope that with the new video card I'm able to use RTjpeg and get at 
least 640x480 without any drops.
I get lots of audio buffer overflows as well. I hope this is because of  
the framedrops (and the poor synchronization..) and not because of the 
quality of my sound card.

thank you
andreas



More information about the mythtv-users mailing list