Layback to tape accuracy

[Sam Goetz]

Hey Kristian,

I’m installing the 6.1 drivers now (on several computers that we use here to lay off) and I’ll get back to you on whether the fix works. Thanks for the quick response.

I should note that it’s not an offset issue. The problem is that the FIRST FRAME of the layoff is getting doubled. So even if I use an offest INSERT edits will still be all screwed up because the first frame will be doubled. Does this make sense?

Sam

[Kristian Lam]

Hi Sam,

Yes, this is indeed an offset issue. When you do an insert to tape, you’ll notice that the “preview” window starts on a still frame while the deck is cueing up to the pre-roll point. Once playback on the deck starts, Final Cut Pro reads timecode from the deck and then tells itself when to play. If everything goes right, it will start playback at the exact same time the deck starts recording. If it starts play back a frame later than when the deck starts recording, the still frame will get recorded onto tape, which is why there is a duplicate frame.

This is why it is important to test out your inserts to tape when you get in a rental deck. Even Apple recommends different offset settings when changing cables as well as decks.

We had an issue with the offsets happening RANDOMLY on inserts to tape that you have been reading about. We believe that this issue will not happen if you use the DeckLink or Multibridge v6.x drivers with Final Cut Pro 5.1.4.

If you have a CONSISTENT offset with the latest drivers (v6.x or better), then it’s a matter of calibrating the Playback Offset option in Device Control Presets.

regards

Kristian Lam
Blackmagic Design

[Sam Goetz]

Thanks for the in-depth reply, Kristian. Our problem IS inconsistent and sometimes happens randomly. But since i upgraded to the 6.1 drivers (two days ago) I have yet to see it. I’ll keep you and the forum posted to whether this occurs again.

Thanks!
Sam

[Sam Goetz]

Kristian,

I am sad to report that your fix does not work for us. You were correct about the offest being consistent with the new drivers, but now, when we change the playback offest to compensate, our video is coming in at exactly the right time, but our audio is out of sync by two frames.

Originally, our playback offset was defaulted to +4 frames. This was causing our layoffs to be exactly one-frame off everytime with a duplicated frame at the beginning. When we reduced this number say to +3 or +1 the offset only grew (if +3 it was 2 frames, +1 4 frames). When we set it one frame larger (+5) miraculously our video came in at exactly the right point and timecode was accurate with the video the rest of the way through. We thought this was our saving grace, but then we noticed that NOW our audio was coming in 2 frames late and continued to be two frames late the whole way through the program. Before, when our video was coming in one frame late our audio stayed in sync. Nothing we have done since this (restarting, changing the easy set-ups, re-trying various ways) has fixed this 2 frame audio sync issue.

SO, in conclusion, our problem is not fixed. Please reccommend a solution if you can. This is SERIOUSLY frustrating for our studio and causing huge headaches and delays.

Thanks,
Sam

[Andrew Yoole]

Sam, your experience is similar to my own on the 3 systems we are running, although I haven’t spotted audio sync issues.

Here’s a post I made recently in a related thread:

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Not a true solution, but a workaround when recording to tape from a point of black:

Insert a single frame black slug at the sequence in-point.

Set your tape in point back 2 frames.

For example in PAL: to record sequence from TC 00:01:00:00, set your deck in-point to 00:00:59:23.

This will record the black frame across two frames of tape, then the correct program material at 00:01:00:00.

There is no workaround for inserting segments into an existing program on tape. If you have to replace the final shot into a 90 minute program with no breaks in it, you’ll have to record the entire 90 min program to tape, using the workaround above.

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Because the standard +4 offset seems the most reliable on our systems, using the workaround above is, at the moment, the only way we are getting reliable records to tape.

[Jeremy Brettingham]

I don’t know whether there’s a PAL 25 / NTSC 30 frame issue here but I’m working PAL SD (Digi Beta) and have found that using a striped tape and Inserting with Edit selected rather than Mastering let’s me drop in totally accurately – once I’ve set up the Device Control parameters correctly (by digitising a clip with BITC via SDI and 9 pin Remote and comparing the onscreen digitised TC with the FCP clip TC).