[mythtv-users] overlay mode available?

[Joseph A. Caputo]

On Tuesday 04 November 2003 03:08, Andreas Bohnert wrote:
> 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.

I hate to burst your bubble, but a P-III 350 MHz is not going to be able 
to handle that.  You'll be lucky if you can get 320x240.  Generally 
speaking, you need at least 1 GHz to handle an analog tuner card, plus 
a little extra (~500 MHz) to handle simultaneous playback.  I'd say the 
most cost-effective option for you (rather than getting a new video 
card, CPU & possibly a new mobo) would be to get a PVR-350.  It does 
MPEG-2 encoding *and* decoding in hardware, so it hardly uses your CPU 
at all, and the picture quality is terrific (so I hear).  You can 
probably get one for about USD$200-250.

-JAC