[mythtv-users] CPU usage during Playback of content from HD-PVR

Brad DerManouelian myth at dermanouelian.com
Wed Aug 13 17:19:05 UTC 2008

On Aug 13, 2008, at 9:38 AM, Robert McNamara wrote:

> Hi Brad,
> Apologies, didn't see the first few messages in this topic until you  
> pointed me at them, so I got it a little out of context.  Up to  
> speed now.  In fact, thought you were a responder rather than the  
> OP.  Anyway, what I was getting at was the even *with* CoreAVC, the  
> 4400+ may be too slow.  CoreAVC will multithread this content,  
> indeed, but it will do so much better with the 1080i captures than  
> the 720p ones.  Reason being, it appears to put the deinterlace in  
> one thread, and the decode in another, still limiting decode to a  
> single thread (and thus, to a single processor).  The 138% you're  
> seeing is likely 100% decode on a single processor, and 38%  
> deinterlace on a second. That's just a guess based on my experience  
> and on helping folks in #hdpvr, but it's been borne out thus far.
> The slowest proc I've gotten things working smoothly on w/ CoreAVC  
> had been a C2D @ 2.4 Ghz, which is slightly faster clock-for-clock  
> than the 4400+.  Even then, I see the occasional skip and freeze.   
> My experience with it has also been that 1080i plays back much  
> better w/ CoreAVC than 720p.  If you're on 720, you might give 1080i  
> a shot and be pleasantly surprised.  If not, you may need just a bit  
> more oomph.
> For reference, I put the link on the HD-PVR page pointing at the HD  
> Playback reports page because I want it fleshed out with more HD-PVR  
> information-- it just hasn't gotten there yet.  I ought to add my  
> own experiences to help others, just haven't gotten around to it.

Thanks! That's very helpful. I will certainly take a look at 1080i  
content. I guess it makes sense that 1080i would be easier since there  
wouldn't be any scaling on a 1920x1080 display. I can actually play  
720p at 100% in mplayer without issue so it's the scaling that's  
really killing me. I wish there was a way to automagically change the  
res of the display to match the content being played. I might take a  
look into that unless someone else has a suggestion about how to do  
that. (This needs to be easy enough for my 11 year old to operate, so  
switching resolutions manually depending on the content isn't really a  
working option.)

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