[mythtv] HDTV CPU utilization

[Chris Mumford]

John:

Thanks for taking the time to reply to my questions.

>> When I watch 1080i content my CPU is always pegged. I'm running the very
>> latest source from CVS on a 3.0 GHz P4 with a NVIDIA 5200 with XvMC
>enabled.
>> This CPU utilization is over twice what I see if I use MPlayer directly
>to
>> watch a movie.
>>
>> When I run MPlayer I'm calling it like this:
>>
>>   Mplayer -fs -cache 8192 -vo xvmc:queue -vc ffmpeg12mc /dev/dtv
>>
>> This is also the line that I put into the TV Viewing setup section in
>> MythTV. I did notice that if I take out the "-vo xvmc:queue -vc
>ffmpeg12mc"
>> from MythTV that it has no difference with playback performance. Does
>MythTV
>> playback with XvMC?
>
>
>I am not sure what you mean saying that you put that line into the TV
>Viewing section of Myth.  What Viewing setup section are you talking about?
>Myth and mplayer don't use the same options.

There is a section to specify a default player to use for unspecified file
types. When I originally wrote my post here I thought that that was where I
should go to specify how MythTV played TV. I was obviously wrong and your
question has helped me understand that - thanks.

>If Myth is compiled with XvMC, then it will use it by default.  There is
>also a checkbox on one of the setup screens to enable/disable XvMC.  You
>can
>tell if XvMC is really being used, by the color (or lack there of) of the
>OSD.  If the OSD is in black/white, then it is using XvMC.

I didn't realize that - thanks for pointing it out. I just tracked this down
in the settings.pro file and have uncommented out these lines to enable XvMC
support. At the moment MythTV crashes after just a few seconds of play, but
I doubt this is due to my recent change. My experience after recompiling
everything every few days is that the MythTV source is often unstable. I
will try again in a little while and hopefully it will improve then.


>That all being said, if you have a 3.0GHz HT P4, why would you want to use
>XvMC?  That much horsepower is plenty to decode HD material without
>resorting to XvMC, and the quality will be much better.  *Not* using XvMC
>will result in most of your CPU power being used -- it should not be
>"pegged", but it will use most of it..

I wouldn't say plenty. I'm about 80-95% utilized so a more accurate
description would be that I "barely" have enough CPU to do all of this in
software. My real reason is because my system really cranks up the fans (and
noise) when the CPU load gets above about 70%.

> I have turned off all of the features that I think would require any kind
of
> video processing like de-interlacing and commercial detection.


> BoB deinterlacing does a VERY good job, and requires almost no extra CPU.

I will try this once XvMC is working alright and hopefully I can leave this
on. I don't yet have a HDTV monitor so I'm going out the S-Video connection
of my card, which to the best of my knowledge is interlaced so I don't think
I want deinterlacing anyhow.

> Any suggestions?

Again. Thanks for the reply.
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