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

Jarod Wilson lists at wilsonet.com
Wed Jan 31 21:17:50 UTC 2007

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?


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