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intermittent brightness increases during transfer

Discussion in 'Digital Video' started by Keebler, Feb 2, 2008.

  1. macrumors 68030

    Hi Folks,

    Has anyone else, in transferring miniDV, seen intermittent brightness increases during the actual transfer?

    Here's the situation: i'm transferring miniDV for a client. I'm using a miniDV camcorder connected to a Canopus ADVC300 (default settings) then FW'd to my Mac Pro. During the capture, footage will suddenly brighten during the same scene. ie. it's not an increase due to filming inside then outside. this piece is of a baby in a car....looks nice..then wham! the brightness increases a bit.

    none of my clients have ever questioned it, but i'm wondering if anyone has seen this before? Could it be a natural tendency of consumer camcorders trying to make the best of the lighting? I don't think it's my transfer set up as I've tried tapes on the same set up, tried using a different camcorder, tried going direct to the mac and not through the canopus etc...etc.. The tapes seem to always brighten in the same sections. if it was random, then I would be worried.

    Any feedback is appreciated. Thanks for reading.

  2. macrumors demi-god


    It's probably the auto-iris in the camera causing the problem.

  3. macrumors 68030

    the camcorder that did the recording right? (not the one used for the transfer?)
  4. -DH
    macrumors 65816

    Why are you going out from a DV camcorder via analog? Why aren't you connecting to the Mac via Firewire. That way all you're doing is a data transfer for tape-to-hard drive with no signal or quality loss. Converting the digital footage to analog then back to digital during capture makes no sense.

  5. macrumors 68030

    absolutely makes sense. the advc has TBC built in and controls to help foster the transfer. plus, for whatever reason, every time i try to capture direct, I have issues with fcp. any quality loss would be minimal at best.
  6. -DH
    macrumors 65816

    OK ... perhaps I'm not understanding your workflow. You stated that you were using a MiniDV camera connected to a Canopus ADVC300 which was then connected to your Mac. Correct? If so then that means the source tape is DV and you're using the camcorder's analog outputs to send an analog signal to the ADVC300.

    In doing so, you're introducing a generational quality loss. Sure, the ADVC300's TBC will help to stabilize analog video signals, but if your source is DV to begin with, you wouldn't have any need whatsoever for a TBC. TBC's only work with analog video and analog video is the ONLY video that would benefit from a pass through a TBC. The purpose of a TBC is to correct timing errors inherent in analog video playback only. It is NOT needed or even useful for live video feeds (analog or digital) or recorded digital video signals.

    If you send the digital source video directly to your Mac via Firewire, no TBC would be needed. Your use of the TBC is much like intentionally puncturing a good tire just so you can place a patch on it.

    Or maybe I just misread your signal path description.

  7. macrumors 65816


    I have to agree with -DH.
    Maybe something wrong with camera.
    I have a Sony miniDV camera or camcorder. I've had some issues with FCE on import. But I use FootTrack with no problems.
    Transfer is all digital.
  8. macrumors 68030

    some good info. I should have clarified that the connection from the camcorder to the canopus is FW.

    Maybe i'll review the settings for FCP again. I tried a quick clip and right away received an audio sampling error when my settings seems to be fine.
    I don't get that with the canopus and the sound is fine in terms of being audibly correct and in sync.

    flynn...do you mean the transferring camera or the original recording camera? I would think the transfer camera, but i've tried different camcorders (different brands) and the issue is still there. :(
  9. macrumors 65816


    So you've got :
    camera <- FW -> ADVC300 <- FW -> computer

    I only have the one miniDV camera, Sony DCR-TRV33. FCE 3.0 (I think)
    With Activity monitor running, FCE uses more CPU than FootTrack or iMovie.
    I think I have lost frames with FCE. Not sure why FCE does this, but I usually import with FootTrack. That way I've cataloged it too. No lost frames.
    I don't FCP, so I can't comment.

    What does the ADVC300 do? Does it clean up?
  10. macrumors 68030

    btw, thanks for the info on TBC. I knew it was to correct timing errors to help with stabilization, but it was explained to me differently. I'm changing my workflow.
  11. -DH
    macrumors 65816

    Canopus' ADVC line consists of AD/DA converters designed to convert analog video/audio signals to digital and convert digital video/audio signals to analog (bi-directional). The ADVC300 includes a built-in TBC (Time Base Corrector) that will help stabilize incoming analog video signals by correcting the timing errors inherent in analog video playback. Note that the TBC feature in the Canopus model is NOT a full frame TBC so it is somewhat limited in how much correction is performed.

    For more information about time base correction: http://en.wikipedia.org/wiki/Time_Base_Corrector


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