Mailing List Archive: Jumpy video and sound/Best system for Myth

Heya,

Well finally got everything compiled last night and I
must say that this software is living up to my
expectations.

I began tinkering with the settings file to try to get
the best possible video quality, and I'm not having
much luck. The system details are as follows:

Intel P3 1.0Ghz processor
512 MB memory
ATI Rage 32MB Video Card
ATI TV Wonder Tuner Card
SoundBlaster Live! Sound Card (MB Onboard sound
disabled)
Brand Spanking new 120GB Ultra ATA-100 5400RPM Hard
Drive with 2MB buffer
Clean install of RedHat 7.3
KDE3.something

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.

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?

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?

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

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. :)

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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