Re: CPU requirements for HDTV MythTV

On Sun, 05 Feb 2006 14:58:04 -0500, Jeff Rife wrote:

Wes Newell (w.newell@xxxxxxxxxxxxxxxxxx) wrote in alt.tv.tech.hdtv:
What did you use to check for dropped frames?

The only thing that matters, my eyes.

So, in other words, you have no idea if you were watching 30fps or 25fps.
This is especially true if you used film-sourced material...dropping a lot
of frames doesn't make as much difference, especially when you have a
monitor set at 60Hz (or greater) refresh.

I'm pretty sure I'd notice those kind of problems, but the monitor is
running 85Hz. So you tell me how you want me to check this and I'll do it
even though it has no bearing on the quality a person can actually see
while watching.

Couldn't tell the difference with
the cpu at 1200MHz or 2000MHz while watching.

Chances are you are dropping a lot of frames and just don't notice it.

And chances are I'm not.;-)

See http://www.avsforum.com/avs-vb/showthread.php?p=6857651 for some
more details about someone who is dropping frames with MythTV and the
same video card and a processor that is a lot more powerful than yours.

Well, there's a big difference here. He states his system is jerky to
begin with.

"I got fed up with jerky video playback on my Linux HTPC and Plus UP-1100P
projector, so I wrote this program today to help me solve the problem."

Mine isn't. The OP wrote the software said he dropped 23 frames out of
1481. Why? How would I know? Maybe it was because he was also running the
test software and that put extra strain on the cpu. Still doesn't matter.
And then there's this there.

Some common causes of judder are:

1. Projectors and other displays that have a fixed update rate running at
a refresh rate different from their fixed update rate

2. Computers with insufficient processing power to keep video and audio in
sync

3. Poor quality sound cards that cause video software to have a hard
time keeping audio and video in sync

4. Video card refresh rate that isn't an integer or 3:2 multiple of the
video frame rate (i.e. 59.94Hz is the ideal rate for 29.97Hz NTSC and
23.976Hz NTSC telecine - if displays could do it, doubling that rate to
~120Hz would be the best).

Number 1 and number 4 are the biggest problems. This Judder Test program
is designed to help track down #1.

So the whole test program isn't even designed to test CPU problems. And
since he mentions NTSC, I assume they are testing with an analog NTSC
card. I don't use NTSC, just ATSC, which requires no conversion to digital
or compression as it comes in as mpeg2 already. So in the end, that thread
is about worthless as most frame drops occur on the incoming signal
conversion and compression if I'm not mistaken. At least that where every
mention of dropped frames has ocurred when I searched the subject.

--
Want the ultimate in free OTA SD/HDTV Recorder? http://mythtv.org
http://mysettopbox.tv/knoppmyth.html Usenet alt.video.ptv.mythtv
My server http://wesnewell.no-ip.com/cpu.php

.

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