[mythtv-users] XvMC De-interlacing

[Brandon Beattie]

On Sun, Aug 15, 2004 at 08:05:14AM -0500, john roberts wrote:
> 
> All HD folks:
> 
> I've been watching the Olympic Games on NBC OTA HD (1080i content).  I was wondering if anyone else has been watching and could comment on the quality of the picture.
> 
> My processor is a 2.6G P4 and I've always had to enable XvMC for mythtv not to studder all the time while watching live TV.  Because of this I can only use the "poor mans XvMC deinterlacing" feature vs. the Mythtv de-interlacing software variations (which I hear are better).
> 
> With XvMC and my 1080i content - watching on a 720x480p Samsung - I see two things when I watch the games:
> 
> 1) On an object which has very small variations in color I see what almost looks like the effect you see when watching a DiVX or an XViD rip (if that makes sense).  Kind of blotchy vs. smooth transitions in color.
> 
> 2) During movement (this must be the interlacing issue) things seem just slightly jagged and blurred.  Nothing like it used to be WITHOUT XvMC de-interlacing turned on - but still not "smooth".
> 
> Anyone have any ideas on the above issues?  Or - maybe someone can comment on NBC's HD content for the games.
> 
> Thanks everyone,
> 
> -John

I should probably do more research on this, but here is what I do know.
MPEG2 only has so much bandwidth for the data.  If you get a lot of
motion you often get jagged edges as there's not always enough bandwidth
to encode everything that is changing in the MPEG stream.  You get this
with DVD's, internet video, and HDTV.

XV (Non XvMC) may be trying to clean up the video stream and smooth out
colors and edges.  XvMC doesn't (Can't? or just isn't wirtten yet?) do
this.  I do know that XvMC quality is much better than a year ago thanks
to several Myth devs.  I would be curious to see what they have to say
about this.

Right now though, unless the video cards can clean up blockiness that is
inherent in MPEG, we will probably see this with XvMC.  If you're not
using the latest CVS, you may want to try it.  There have been several
improvements in the last few weeks for de-interlacing that have helped
me.  I'm running 1024x576 on a DLP projector and the only thing I see
often that is anoying is blurring on panning.  Everything else looks
rather good for me.

I do have to ask those watching HD, is "Hey Tom! Wacha Watching?" getting 
as anoying for you, or is just my local station that's playing that
Sony commercial every 5 minutes during the HD Olympic streams? 

--Brandon