firewire webcam dropping frames: options?

Discussion in 'Amateur Video Production' started by Eric Dobbins, May 29, 2005.

  1. Eric Dobbins

    Eric Dobbins Guest

    I am using a firewire webcam with a Dell Inspiron P-4 2650. I added an
    Adaptec DuoConnect dual USB2/ Firewire card. Since the hard drive in the
    laptop is fairly small (~30 GB), the hope was to be able to capture
    uncompressed AVIs with the firewire camera and send directly to an external
    USB 2 hard drive. However, I am having problems. If I capture and send to
    the laptop's internal hard drive, I can use the maximum frame rate of 15 fps
    and capture all frames uncompressed. However, if I try sending the stream
    to the external USB 2 hd, plugged into the same card that is used for
    firewire camera captures, I end up with about 50% dropped frames.

    My first guess is that my external USB 2 hard drive is too slow and maybe I
    should update it to firewire. Would this eliminate the dropped frames? Or
    is it that having both the camera and hd plugged into the same card is too
    much for the bus and slowing it down? I wouldn't think it would be since I
    had a similar setup a couple of years back that worked fine on a slower
    machine.

    As a last resort, I have been thinking about trying a lossless compression/
    decompression algorithm as my software supports them, but I really prefer
    uncompressed video.

    Appreciate any advice or tips.

    Thank you,
    Eric
     
    Eric Dobbins, May 29, 2005
    #1
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  2. Are you connecting the camera and hard drive via a hub into
    the same USB port on the PC? Or are you plugging them each
    (separately) into different USB plugs? You may have a problem
    because both devices are sharing the same USB node.
    But the "slower machine" may have had better implemented USB
    ports. (Like maybe separate USB controllers, contrasted with
    different ports on the same node.)
    Without any context, seems strange that you would consider
    uncompressed storage for a low-quality pre-compressed
    source (the webcam).
     
    Richard Crowley, May 29, 2005
    #2
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  3. Eric Dobbins

    Bob Fields Guest

    No, I'm not using a hub. The PCMCIA card has both USB 2 and firewire
    inputs. The hard drive, being USB 2, is plugged into the USB 2 port on the
    card and the firewire camera is plugged into the firewire port, also on the
    card.


    On the slower machine, I ran a similar configuration. It was a PII with a
    two port PCMCIA USB 2 card. The webcam was plugged into the one port and
    the external hd drive into the other. I had very few dropped frames with
    this configuration.

    This is a high end webcam... perhaps "industrial camera" would have been
    better terminology. It offers uncompressed AVI capture at 15 fps via
    firewire. That is, if I can get the frames to stop dropping!

    Eric
     
    Bob Fields, May 29, 2005
    #3
  4. "Bob Fields" wrote ...
    Can you get another of those cards? It appears to have had better
    throughput than the one you are trying to use now.

    So are you "Eric Dobbins" (the original poster) or "Bob Fields"?
     
    Richard Crowley, May 29, 2005
    #4
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