Capture Rate Questions ??

pmc181 wrote on 1/6/2003, 8:01 PM

We have been getting a lot of dropped frames in our setup and hope some of
you can answer a couple of questions we have before we buy a separate hard
drive. We have the DMA engaged and had our disc defragged. Here's our setup.

Sony analog handycam
Belkin Video Buss II connected to a USB connection. Emachines tells us our
USB is a usb-2, and not usb-1 . I couldn't find out how to verify this.
Emachines 1.5gh, 586 meg ram, 40gb hard disc.

For a 7 minute clip at 30 fps, we are loosing from 200 to 300 frames. We
dropped down to 15 fps and lost under 50. Still way too high though.

Here's the questions:
1. If you are capturing at a rate anything under what the camcorder is
playing, 30 fps standard, aren't you loosing frames anyway ? I mean, when
you hit play on the camcorder, it still plays at the standard frame rate,
but the capture program is only recording at whatever rate you have set in
Vegas, right ?

2. The Belkin spec for the Video Buss II says it will capture CIF
resolution at 30 fps or 15 fps at VGA resolution. What is CIF and if
acceptable quality, where do I set this ?

3. And last, do I just have my thinking messed up and the capture rate
really only determines how long it will take you to capture a clip and
when set to a lower capture rate, the program will still get all of the
frames from the camcorder anyways ?

Thanks,
Paul/Pat-Magnum Blues

Comments

Chienworks wrote on 1/6/2003, 10:12 PM

The "capture rate" you're mentioning specifies how many frames per second the computer will see. So if you capture at 15fps, you get 15 frames per second. The camera is still playing at 29.97fps, so skip just about every other frame, capturing just about half of them.

CIF is 352x240 pixels, compared to VGA being 640x480. So CIF is just about half resolution or 1/4 of the frame.

Your thinking is correct. Capturing at a slower speed means fewer frames per second, and this does not affect how fast the camcorder runs.

Just for the record ... USB is not a good way to capture video. Even though USB-2 theoretically has a transfer rate high enough to handle video, it's not very stable. To get good captures you should be using firewire (IEEE 1394) and some sort of external analog to DV converter, such as the Canopus ADVC-100.

pmc181 wrote on 1/7/2003, 6:00 AM

Thanks for the great info. I do have a firewire card installed. If I can't afford the Canopus right now, what other firewire external analog to DV converter would you recommend in a little lower price range ?

Thanks,

Paul

rextilleon wrote on 1/7/2003, 8:26 AM

I noticed in your hardware configuration that you only mention one 40gig hard drive---that could be part of the problem-----you should have one dedicated HD to capture video, and one for your applications etc. Sonic recommends that your second drive should rotate at 7200rpms.

JJKizak wrote on 1/7/2003, 9:07 AM

Ditto, it is absolutely imperative you have 2 hard drives. This will totally
eliminate any conflicts with capturing and operating system operation.

James J. Kizak

jthor wrote on 1/7/2003, 11:15 AM

And you will find 40gb hd isn't all that much either. With the .avi uncompressed files created from the capture, GB's disappear fast as you work on projects and keep backup copies. Don't get rid of original .avi files until you are very happy with your product. I am learning that the hard way.
I think many of us are using DV camera's with built in converters. I use a Sony DRV840 which also reads my older Hi8 analog tapes from a few years back.

pmc181 wrote on 1/7/2003, 11:34 AM

Thanks all. After reading all your suggestions, it seems as though we may be better off spending our money on another separate hard drive and maybe the Cannopus converter instead of the Belkin USB converter. One last question.

If I plan on upgrading to a digital 8 camcorder in the coming months, would you all still purchase the Cannopus converter to get your VHS and other tapes into DV ? Once I go with the digital camcorder, I'll just be capturing straight into the ADS firewire card I have, right ?

Paul

nolonemo wrote on 1/7/2003, 4:11 PM

You won't need the Canopus if you get a digital-8 with analog pass-through (plug VCR deck into AV-in on camera, which converts to DV on the fly and passes through to PC via firewire). (BTW, with this method, dropped frames virtally cease to exist.) However, I understand that the latest crop of Sony digital 8s don't have analog pass-through, so check specs carefully before you buy.

pmc181 wrote on 1/7/2003, 10:33 PM

Awsome idea !

Thanks All

HeeHee wrote on 1/7/2003, 11:44 PM

On the contrary, if you can afford the Canopus, get it! It will allow you to capture full resolution NTSC or PAL video and at 1/5th the file size as uncompressed AVI. You can then keep it hooked up to the VHS deck and leave your digital camera, when you get it, free for what it does best... shooting videos. When you need to transfer footage from the digital camera you can hook it up right to the DV port on the front or back of the Canopus. It is also much cheaper than buying a Digital camera with passthru. You can always use your analog camera with the canopus until you are ready to go all digital.

Spirit wrote on 1/8/2003, 8:50 AM

The Osprey 210 is a cheap but very good analog capture card. Never had any problems with dropped frames. Different story when I was using some Pinnacle USB garbage. I got so fed up with it I simply unplugged everything and tossed the lot in the bin.
Life's too short to fool around with substandard computer gear.