CPU usage & frame dropping

[Dwight]

I've noticed the lower I capture the lower my cpu usage in Virtualdub is and the HIGHER THE CHANCE OF FRAME DROPPING.

At 352 x 288 it varies from 2% - 16%
At 640 x 576 it was over 40% all the time.
640 x 480 about the same as 640 x 576

Now this is a bit annoying... why won't it use more cpu ? clearly
there's a connection between dropped frames and the usage.
At 352 x 288 Vdub uses my pc like a ferrari that's been driven
in a closed circuit at 20 mph which makes no sense.

And I have no hd space to capture over 1 hour video at the higher
resolutions.

[uxbridge]

You probably have better CPU than Hard Disk and are capturing uncompressed or with huffy.
Capturing with a modern CPU P4 or Athlon Class at the resolutions you are using is easy for the PC, and you can go as low as 10 or 20% CPU usage.
But your HD is not as fast, and might not be able to cope with the amount of data you want to store. The less compressed and the higher resolution, the worse it is for your HD, even if they are the best you can buy.

When you capture, look at the average size of the frames captured.
Then run the VDub tool to assess speed of your disks. You'll probably find that your HDs cannot cope with the average frame size you're using for capture.

If your machine is powerful, as I could think of, the solution is to use a powerful compressor such as XvID with high quality settings.
It will make your CPU utilisation to go up to 70-80% (you might have to play a little before you find the right compromise) and your frame size to reduce dramatically so that your HDs will not be the bottleneck any longer. Another advantage with this approach is that you'll need much less disk space.

Ciao

[Dwight]

My hd is an 80 gb ibm deskstar 7200 RPM with a 50gb partition for captures only which I defrag after each capture has been encoded and burned and wiped away. Pc is 1,7 ghz.

I capture YUV, have tried huffyuv also. My hd should be up to it...or is 7200
too darn old already ? The vdub diagnostic never gave me any notion of being too slow. I mean..if I want to have zero frames dropped captures I have to capture at minimum 480 x 576 ... I hardly get the job done without dropping (although the dropping is too low to make it out of sync) in the standard vcd resolution capture (where the cpu usage is minimal).

The times I've managed to do a zero drop capture in vcd resolution the cpu usage has been over 20% ...is it just virtualdub ? I use the sync version btw. Most times the usage is the all time low one.

[uxbridge]

The HD should be OK but have you DMA enabled? what is the maximum frame rate Vdub gives to you as a result before dropping? there is a Vdub utility that does precisely this task and gets you a number back. Compare that number to the average frame size of your captures.

Anyway how many frames are you loosing?
It is nearly impossible to get a zero frame capture, because of differences in syncronisation between audio and video. if you loose, say, 5 or 6 frames in an hour, that is acceptable.
If you loose more, it is not.

Try the standard version of Vdub also.

[Gazorgan]

A 7200 RPM drive is only part of the battle. If you have another slower drive on the same cable, then you could be in PIO mode 4 instead of UDMA 100 (massive speed difference). DMA needs to be enabled, and that's a M$ software setting. Having your CDRW on the same cable as your Harddrive is a definate no-no.

Partitioning your drive doesn't help you at all, it's still your boot drive? To minimize dropped frames you generally capture to a non-system drive (I don't, but I can tweak my system on the fly).

I routinely capture a 2 hour clip with zero dropped frames. I only drop frames when I stop/start the capture on the fly (IUVCR doesn't stop/start very well). I never could get VDUB to capture worth a dam.

[Dragonsf]

One remark:
I'm capturing from an external DV device (thru FW) and I noticed the following effect:
With no other program running, VDub generates around 1% dropped frames at CPU usage 2% (on to an UDMA 100 drive).
Using the same setup and other programs running (CCE during encoding), the CPU usage goes up to 6%, but the frame drops counter goes below 0.5%. Any ideas how this could happen?

[Dwight]

I have dma enabled of course. The only program I know on vdub is the benchmark utility and it certainly does not suggest my hd is too slow.
The hd is the only drive on the main ide.

I repeat again. I only drop frames in lower resolutions.
I drop zero frames in higher resolutions. Cpu usage
is always super low at low resolutions..and higher ones
have it higher and it does not varie that much during capture
as to in low res. captures.

My hd is not the issue here. For some reason virtualdub
does not utilize my processing power to the fullest unless
I capture at a large resolution.

Zero drops impossible ? Have done it with every single capture
I've done at 480 x 576 upwards resolutions. I drop around 8 frames
to 20 in lower resolution I've capped (352 x 288) which has not
made any difference to my eyes to the sync of audio & video while
using vdub sync. The only times I've reached zero drops at the low
resolution 352 x 288 has been when I've not given the pc a clean
boot before capturing (ran a few programs) although I doubt this had
that much effect. Then the usage was at over 20% standard but this
was a rare occasion.

[MrKGB]

I have a similar problem with my winfast 2000TV card if I use it with btwincap drivers: it captures without drops only at 720x576.
If I use the drivers which come with card I have no problem.
I fix this problem like this:
use PicVideo MJPEG codec @ 720x576, then resize the video to desired resolution. IMO it is even better if source is noisy.

[Champion_R]

Windows ME could be your problem. C'mon a 1.7ghz on Win9x. I reckon a better OS would go a long way.

[Dwight]

You might have a point with ME being the problem... I do have
the option of installing 2000 or Xp pro..but my run with Xp Pro
lasted 4 hours and I un-installed it back to Me...it took forever
to start and crashed and crashed and crashed

Maybe I should have installed it to an empty hd instead of over WinME though

[Champion_R]

Best way to install a new OS is a fresh install. 9x to NT based is a disaster waiting to happen. Prehaps backup your hard disk and try a fresh 2k or XP.

[Dwight]

Hmmm...can I install WinXp on my hd and maintain WinME and choose in startup which OS to run..would this work ? I'd only use Xp for the 'HEAVY' stuff and ME for ....well I'd like to try Xp but not loose the current windows or install over it..I got tons of software installed and such.

[jarvis1781]

you might also think about getting more RAM

128 is quite a bit low for doing video work.

and the cache size on a Celeron is smaller than a P4 as well

other than that just do what works for you

[Dwight]

Actually I have 384 mb, not 128...maybe I need to update my profile

[Champion_R]

Yes you can run them side by side, but it only works well if u have 2 partitions or drives.