[mythtv-users] playback is smooth, yet lacking... seems like smootly missing frames

Bill Bill at explosivo.com
Wed Jan 31 21:30:28 UTC 2007

On Wed, 31 Jan 2007 16:17:50 -0500
Jarod Wilson <lists at wilsonet.com> wrote:

> Bill wrote:
> > On Wed, 31 Jan 2007 14:24:58 -0500
> > Jarod Wilson <lists at wilsonet.com> wrote:
> > 
> >> Bill wrote:
> >>> Sorry if this is obvious.  I am not sure what to even stfw on for something like this.  I've tried, but nothing seems to match what I would describe this as... 
> >>>
> >>> I have a 2.4ghz P4, running a pvr500, pvr350.  Output is from an nvidia fx5200 (AGP 4x) via DVI-D to an LCD TV (westinghouse).  I am outputting at 1080p.  
> >>>
> >>> My sources for video are standard tv into the tuners and recorded at 720x480. 
> >>>
> >>> Now, I am absolutley thrilled with the quality of the recordings and how well mythtv scales it up for the LCD at hi-res.
> >>>
> >>> But, it seems a little "off".  If I had to describe it, I would say that something is very smoothly and evenly dropping frames.  Not the kind of dropping where a whole handful goes away, and its noticable, but more the movements of the people on the screen just get a bit jerky... but not terribly so.  
> >>>
> >>> I am really having trouble describing this.  I guess if there is 24 frames a second, it would be dropping maybe every 5th one or something...
> >>>
> >>> Is this something that it does when it gets overworked or something?  The cpu is at about 69% during the playback.
> >> Whoa. Shouldn't be that busy for SDTV playback. What does 'xvinfo' 
> >> (while in an xterm on your display, or logged in via ssh as your X user 
> >> following an export DISPLAY=:0) say? With some nvidia cards and the 
> >> nvidia driver, if the x composite extension gets enabled, xvideo WON'T 
> >> get enabled. Easily fixed by tacking a few lines onto the end of your 
> >> xorg.conf though:
> > 
> > I have the composite disabled in my x config and inn my X.org.log I have this:
> > (**) Extension "Composite" is disabled
> > 
> > Regrettably would have been a nice easy fix
> > 
> > Here is my output from xvinfo - no idea what any of this means...
> > ------------------------------------------------------------------
> > 
> > X-Video Extension version 2.2
> > screen #0
> >   Adaptor #0: "NV17 Video Overlay"
> >     number of ports: 1
> >     port base: 244
> >     operations supported: PutImage
> [...]
> Sorry, what I should have asked was "does xvinfo say xvideo isn't 
> supported?". I'm not certain what everything means either, was just 
> wondering if you were possibly w/o xvideo support for some reason, but 
> its enabled, so scratch that thought.

> >>> I want to try Xvmc tonight to see if I can get it down a bit, and hopefully the picture wont suffer.
> >> Absolutely no reason you should ever need xvmc for sdtv.
> > 
> > Ah, I thought that since it was an mpeg2 file, and I was trying to scale it up to the 1080 it may have helped.
> I suppose it still could help, I was simply meaning that your system 
> ought to have more than enough oomph to handle playback w/o it. My box 
> is like 10% busy playing back sdtv at 1920x1080p. Do you see the same 
> behavior if you try playing the recorded files back w/mplayer, or try 
> playing them on another machine?

With my PVR350 and using the svideo out on that I would only see a few % used.  

I was thinking that since mythtv / computer was scaling it up to fit the big screen it would require a lot more image math or whatever kind of voodoo it does behind the scenes.  Especially since it is not actually at that resolution natively...

Of course I have no idea what I am talking about.

I shall try it with mplayer and possibly another front end - if I can build one up.  My desktop is a good candidate for a front end :)

I've tried streaming them to work over my OpenVPN connection - but that just really does not work very well :)



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