[vdr] Any really working HD video output systems for VDR?

Tony Houghton h at realh.co.uk
Fri Jun 5 14:48:27 CEST 2009


On Fri, 5 Jun 2009 11:17:54 +0200
<jori.hamalainen at teliasonera.com> wrote:

> > I think it would also help if we could reach an agreement 
> > over the terms "stable" and "good quality" and "everything 
> > is working" because they are highly subjective.
> 
> For me I'd add a class; "Set-top-box quality"
> 
> It would mean that no judder and studder on HD-quality. With VDPAU
> the problem still might be "50Hz vs 50.02Hz" -thing so you cannot get
> frame accurate display. With every 5 seconds you might have duplicated
> display of frame or dropped frame. This is not acceptable by my
> standards. Typically "Set-top-boxes" can display frame accurate.

I've always found [1] that playing TV straight from DVB reception with
xine the frame rate is reasonably smooth, but while playing back a
recording there are definitely more dropped frames. I would have
expected things to be the other way round, but it's occurred to me that
with "live" TV xine may be using the source as its clock reference,
whereas with recordings it uses the system clock, and there could be a
worse discrepancy with the VGA clock in the latter case. Live TV
playback could probably only be improved by using the frame rate control
patches, but recording playback could be improved by basing all the
timings on keeping in sync with the VGA interrupts. All this is made
more complicated because were' not using a RTOS.

[1] Both with dfbmga output and Xv with NVidia HDMI.

-- 
TH * http://www.realh.co.uk



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