Two DigiBeta sync questions

[idris]

I've been doing some feelancing at a studio with IIRC an HD3, Sync i/o and V10.
Thet're set up to take SDI pictures and all 4 audio tracks from DigiBeta PAL (DVW500) into PT, and layback audio to the same deck.

There seem to be a couple of sync related issues that have arrisen since they upgraded to PT8. They may not be PT related, but as far as I know only the software has been changed, no hardware configuration. Unfortunately there was no one around who could shed any light on the subject and I'm just trying to eliminate issues before I'm there next.

I've been told by the staff dubbing mixer (who I was covering for) that sync has to be taken via Serial TC (apparently PT complains of no sync if locking to LTC or VITC).

Issue 1 : When the video is recorded into PT, it is 1fr late. (I've checked this with both BITC and matching frame cuts.) ie pictures that should be at 10.00.00.00 apear on the time line at 10.00.00.01

Issue 2 : When laying back to tape, the sync seems unstable - I'm used to being able to punch in with PT locked to the deck for only a second or two. In this case it seems to need maybe 5-10 seconds, or there's a splat when you punch in. Though sometimes an earlier punch in is fine, and sometimes even 10 sec isn't long enough. I've tried different settings in terms of jam sync and freewheel durations but without a quick solution.

Has anyone else seen similar issues?

I have to confess I've not had much time to investigate properly, I've have had to work round these issues, and they're not really my responsibility to fix. Add to that, I can't say for sure that they're PT issues and I'm not sure when I'll be sat in front of the same rig next, so I'm not sure I can supply much more info just now.

[MIKEROPHONICS]

Two quick points

The BITC on the picture can be a frame out if it is at the bottom of the picture - a weird sony software oddity. This could be your red herring?

It sounds like the digibeta may be poorly referenced - is the stop light flashing? Sync IO and digibeta must be referenced from same video reference and PT run to video reference.

It does not matter a jot whether the positional info comes up serial timecode or from LTC. It is a commonly held misconception )certainly in the UK) from the hordes of "me too PT computer operators" that serial is better. IMHO LTC locks far faster than serial.

Were you in slave or master mode?

PT should use 9 pin for control info - got here stuff, then lock to the positional info given by the deck (either by the serial or by LTC), then when synchronized ignore the time code and resolve to reference.

Splating on drop in would indicate the AES is not referenced to the deck or PT is not resolved to frame edges. Have you tried an analogue drop in? Does your drop in give you channel errror lights on the digibeta front panel (look at the V and A errors on menu 12 think it is)...

Food for thought I hope

cheers

[Frank Kruse]

Originally Posted by MIKEROPHONICS

Two quick points

The BITC on the picture can be a frame out if it is at the bottom of the picture - a weird sony software oddity. This could be your red herring?

Sidenote: It´s actually the other way around: A Digibeta will show the TC one video field OFF (not a whole frame) when you insert it at the top of the frame.

After capturing to a QT card this can trun into a whole frame if the hardware only captures every second field.

This is especially problematic when working with 24fps playouts to a PAL tape.

So it better to always insert the TC at the bottom. This applies to all Beta SPs and Digibetas.

[idris]

Thanks guys.

I can't remeber whether the BITC was at the top or the bottom (thier engineer did ask me this as well) but I know the front pannel of the deck and the BITC matched, and the picture cuts on the QT matched those on tape with respect to the BITC, so I'm pretty confident that's not the issue ... but I'll check next time anyway.

Mike - I've always found Auto LTC / VITC to be best too, so I'm disappointed I can't use it there.
Audio and video are being ingested by PT with PT as master and DVW as slave. Laybacks are the other way round. (It never occured to me to do it any other way?)
I don't know if the stop button is flashing, but that does ring a bell. I'm afraid I have no idea where anything's referenced (there are some odd things in that sound suite!!!) but I'll have a look next time.
When you say Sync IO and digibeta need the same referenc, do DAs have any impact on that? (I don't kno if it's an issue - just thinking through the options.)
I don't think there are channel error lights coming up. is it easy to verify that PT is locking to frame edges. (IIRC the cabling isn't in place for analogue into the deck.)

Frank - it's all 25 fps / PAL for TV, but I shall make sure it's at the bottom in future.

[Postman]

On Sony Digibeta, the burn must be in the bottom third of the image to be guaranteed accurate.

There have been various complaints for years of sync being 1 frame off, randomly, when using serial TC. It WAS a problem many years ago, but is supposed to be long-ago fixed. If there is a problem now, it is likely a sync problem. PT and Digibeta are not looking at the same ref signal?

apparently PT complains of no sync if locking to LTC or VITC

supports my question above. IF you set SyncIO for positional AND speed reference from LTC, it will work but will need extra time during pre roll to stabilize the speed. OTOH, if you set SyncIO for positional reference from LTC and speed reference from something else, like video ref, and that speed ref signal is missing, PT will complain! The most reliable I've found is LTC for positional, and video ref for speed. The fastest lockup is usually serial TC for positional, and video ref for speed, but that is the combo I personally do not trust (because of those old problems).