Why do frames drop with such low CPU usage?

[scottb721]

The Virtualdub stats screen shows only about 30-35% CPU usage.

Why do I still get dropped frames?

Are dropped frames unavoidable?

What ratio of dropped frames can be regarded as acceptable and won't affect the output?
I can get several thousand frames between dropped frames.
Is this considered good?

I'm using Huffyuv 2.1.1 in the compression option,
The compresion ratio during capture sits around 1.7:1

It doesn't let me choose YUY2 in the custom video format window, just UYVY. Does this affect anything?

Even when I reduce size from 720x576 to 480x576 the CPU usage drops accordingly but frames still get dropped.

What other settings in VDub are mandatory?

Thanks so much!
Happy new year

[AngusMacGyver]

Hello! I think you could use PicVideo MJPEG codec. Try it. 1.7:1 is almost uncompressed video. Probably, your HD is not fast enough to handle such high transfer rate.
I hope it helps you.

I'm sorry. My English is bad.

[menaceboy]

what speed hard drive you got?
i cap on a 7200rpm ata100
i make sure to partition a small portion of it and format it before i cap something important
if there is something on that partition i defrag the freespace so the write head wont jump around the disk and create dropped frames

[crahak]

Although it could be a HD speed issue, using a 5400 rpm drive never made me drop frames, and also, most PVRs do use 5400 rpm drives, so it can't be that bad.

Most dropped frames are generally caused by background apps, screen savers, and such. Your cpu load can be very low, but if the computer just has to wait for the tiny fraction of second after some background app, it might not have time to capture the frame... Disable all the startup junk, enable DMA and the like and try again?

[vitualis]

Depending on your hardware, you will also get some dropped frames simply because the clock on your video card (video) and sound card (audio) are not perfectly in sync.

VirtualDub will then drop the occasional frame to maintain video and audio sync. This is a good thing. It is also unavoidable unless you get another soundcard.

Regards.

[hwoodwar]

Looking at your system specs, it looks like your system is powerfull enough for little to no frame loss.

This guide may help you: http://www.vcdhelp.com/forum/userguides/81808.php It says it is for tuning for ATI capture cards, however most of it applies to capture systems, in general.

"What ratio of dropped frames can be regarded as acceptable and won't affect the output?" This is one of those things, that everybody has their own opinion. To me 45-60 dropped frames in one hour is about my maximum limit, providing they are not all in the same place. I tend to look over at the capture system every 10-15 minutes and make a mental note of how many frames it has dropped. A few dropped frames here or there you probably won't notice. If they are sequential there is a more likely chance that you will notice them.

With Windows XP there are some other things you can turn off that may be ocasionally causing dropped frames, like: automatic updates, hiding inactive icons, use personalized menus, etc.

[vhelp]

scottb721,

Sometimes, all it takes is "another capture card" !!
Sorry, but sometimes, your hardwared (motherboard vs. soundcard vs. gc vs.
cap card vs. tuned driver install)
don't perform the "concerto" very well - they all have to be in sync w/ ea. other.
If not, then the slightest anything, will give you a drop or two or dozen, etc.

I fought this battle for a VERY long time. I won in the long run, after many cap
card purchases. And, the winner was the most talked about card, WTVGO !!
Coupled with an ESC K7S5A w/ XP1800+ combo, I had zero framedrops (uncompressed)
w/ Huffy, drops were ZERO, unless source was poor, ie VHS or bad cable or
something.

W2k and XP are resouce hungry OS's. You may consider that as a piece of
the pie. So, unless you hunt and destroy (piece by piece) what is causing
your framedrops, you'll be batteling it out for a LONG time.

I DON'T think that it will matter HOW fast your PC is, if your setup is NOT
properly tuned, you'll be grinnen your teeth, no matter WHAT OS your using.

The capture card you have now (per your computer details) I have never heard of.
That could also be the issue.

Remember, everything has to be in sync or else..

IMO, there is only one alternative to your frame drop madness, but I'll
reframe from mentioning this device here But, once you've tired
yourself out, and if you are SERIOUS about your video endeavor, you'll
find out what I'm talking about and spend the $$$.$$'s for it. I did.

-vhelp
(gc=graphics card)
(wtvgo=wintv go)
----------------------------------------------
Happy HOLIDAY all.

[crahak]

My capture machine is a XP 1600+ with 256megs of DDR on a ECS K7S5A too. (Great board, unless you're stuck with the wrong DDR, then you gotta solder a resistor on it, but anyways). I have captured with a rage fury pro, a AIW 7500, a bt8x8 card and now with a MSI GeForce Ti4200 VIVO, (virtualdubvcr, and either huffyuv or a mjpeg codec. Oh and one of those P.O.S. sb live 5.1 if you wonder, and on XP) and 99.9% of my captures have 0 frame drops... So I'm thinking it isn't that hard to get one to work properly, unless it's very uncooperative hardware...

[scottb721]

Hi all,
Thanks
Even though I had 38Gb free on my 7200rpm hard drive it had fraged files spread through out.
I have defraged so everything is together on the drive.
I'm just waiting to give it another go.
I turn off preview when capturing.

The first guide under VCDHelp\Capturing shows an earlier version of VirtualDub, Is there a guide for the current version?

Are these settings correct for VDub?
Video\Compression\Huffyuv2.1.1\OK (MJPEG isn't listed)
Set the custom video format, in my case 480x576, UYVY. (I can't select YUY2)

Can anyone explain the "Compression(Compatibilty)" option that is listed under Video tab?
Do I also select Huffy in this option as well?

Thanks again and Happy New Year