[mythtv] Jumpy video and sound/Best system for Myth

[Isaac Richards]

On Tuesday 27 August 2002 09:44 am, Andrew C. Ohnstad wrote:
> My goal is to use this system instead of a DirecTiVo
> in my home theater.  My home theater uses a ceiling
> mounted projector to make a 7 foot by 9 foot image on
> my wall.  Since it's such a big image it needs to be
> pretty clear.
>
> I have tried both encoding methods.  With the quality
> numbers set somewhere in the middle or towards the
> better end of the middle everything works fine, but
> the video is really blocky.  When I move the numbers
> towards the 'best' settings I get jumpy video (dropped
> frames?  If so, lots of them).  It also seems that the
> audio is BARELY behind the video.  I am not suffering
> from the 'mute your line in' FAQ.  I witnessed that
> when I first set up the box and this is not that
> problem.  In my case the audio is maybe half a second
> behind the video.

Hrm.  On my box, audio's perfect with the rtjpeg codec, and one frame ahead 
when I use mpeg4..  dunno what to tell you about that.

> I've run top while mythtv was up and I'm running
> around 60% cpu.
>
> Also, I have X running at 800X600.  Does native
> resolution make a difference to MythTV?  Would going
> down to 640x480 make a difference?

It shouldn't, since it's using the video hardware to stretch the video to 
fullscreen.

> I am not adverse to throwing more hardware at the
> problem if that's what it will take to fix it.  My
> initial concerns are processor (I know Issac is using
> a 1800MhZ Athelon, perhaps I can grab one of those or
> a P4 2.0G) and hard drive (would a ATA-133 or 7200RPM
> drive make the difference?).  I also have a Matrox
> Mellinium G400 64MB video card that I will try.  Does
> video memory make a huge difference?

More cpu would definately help, as for the harddrive, what's the output of 
hdparm -tT /dev/[your drive it's recording to]?

> Basically any advice/experiences would be helpfull.
> Issac, what settings are you using with your MythBox?
> Is the video quality 'satisfactory' to you?

I've been using 640x480 with the mpeg4 codec at the default quality settings 
that are in the config file.  Takes, oh, 80-90% cpu, depending on the scene.  
Looks rather nice on my TV.  I'll probably switch back to the rtjpeg codec 
once the dual tuner and the automatic reencode stuff's working, just to cut 
down on CPU usage.

> Thanks in advance, and congrats on a great product!
> =-=Andrew
>
> P.S... I'm a technical writer by trade.  How would you
> like some documentation writing assistance?  I am
> definatley NOT a code monkey, so maybe this is my best
> chance to help out.  :)

If you want to write docs, I'm certainly not going to stop you =)

Isaac