• Apple Final Cut Pro Legacy

  Occasional capture out of sync – not consistant – not long clips

  Posted by Gary Hughes on November 12, 2005 at 10:38 pm

  I’ve seen a lot of posts here about sync issues, but this one seems to be different. First, let me say this is happening on my system (specs below) and also on my producers iBook.

  The occasional clip gets batch captured out of sync by a whole second and sometimes more. After identifying the problem clips, I make them offline and recapture them. Sometimes I have to try 3 or 4 times, but eventually, the clip captures correctly. This seems to be a lot better when using RS422 instead of firewire for deck control (still using firewire for audio and video). This is completely random, but I would say it happens in one out of 20-30 clips with firewire control and much less with RS422. Length of clip does not contribute. It happens with short or long clips (for me, a long clip is 5 minutes).

  This is not a monitoring issue. I’m using a Blackmagic Decklink Extreme card and I’m monitoring video and audio out of that card. If it were a monitoring issue, it wouldn’t be so random. My producer monitors on his ibook screen and out of his headphone out of the ibook.

  This isn’t a frame offset issue as most of the time, sync is perfect. (BTW, my frame offset is set to 4.)

  This is not a sample rate issue. I carefully make sure that I capture 48k clips with a 48k preset, and 32k clips with a 32k preset.

  This is not a long clip audio drift issue as most of the time the clips are less than 1 minute, and always (when the problem exists), it is out of sync from the very start of the clip.

  Here’s my specs:
  G5 Dual 2.7 with 2GB of Apple installed Ram
  Internal MacHD plus G-Tech G-Raid 500GB Firewire 800 drive connected to a third-party pci card.
  Blackmagic Design Decklink Extreme
  Sony DSR-45 using miniDV and DV-Cam footage.
  This particular job is a 6 camera shoot (5 cameras plus a line-cut) with matched time-of-day timecode.
  It doesn’t seem to make a difference if entourage or iChat is running, all else would certainly not be running while I edit.

  Any ideas,
  Gary

  Gary Hughes replied 20 years, 9 months ago 1 Member · 1 Reply
• 1 Reply

• 

  Gary Hughes

  November 13, 2005 at 4:03 am

  New info:
  I just came across a clip that (previously) I thought was in sync. Truth is, it was, and is, in sync before a timecode break but out of sync after. Since the timecode break was after 1 minute into this 2 minute clip, it wasn’t until I played it past that point that I realized what was happening. From the timecode break to the end of the clip, FCP generated new timecode so that there was no actual TC break in the “Captured” clip (this makes sense to me). So evidently, what is happening is that either the audio or the video skips some frames at the break, but the other does not skip, therefore rendering it “out of sync” (this does not make sense to me). (Before anyone critiques me on my logging choice here, the producer logged the clips. I would have created 2 clips out of this if I were logging.)

  If this is the same issue that caused all the other out of sync clips, the timecode break must be appearing during the decks preroll or during the handles, because they were all out of sync immediately. If this is not the same issue, then I’m still curious what’s causing the other issue.

  Any thoughts or confirmations would be greatly appreciated.

  Thanks,
  Gary

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