USD,Linear time code Sync

[PeterD]

Recently have had to do several sessions using 40 Protool tracks or more, synced up to an analog 24 track machine.The 24 track is freewheeling,that is..it's not being driven by house sync or any other external synchronizer.I'm feeding 30fps timecode from track 24 into the timecode input of the USD which appears to be receiving properly(it's display is showing the advancing TC numbers)The USD settings are as follows..LTC for clock ref and LTC for positional ref.I was under the impression that the USD could accurately chase to within a 1/2 frame or so purely from incoming Timecode in this manner?Now I realise the correct method is to have both the 24 track and the USD slaved to a master sync device but in this particular studio this is not possible.My problem is this..ProTools chases fine for a short while and then jumps out of chase and just sits therewith the "waiting for Sync" message flashing.I open up the Peripheral dialog and reselect the USD and Printer port and everything will be fine for a while until it happens again..sometimes even this doesn't help and I have to close and reopen the session to get it to recognise and lock back up.All the timecode settings are correct as far as frame rate,non drop etc.Is this a problem with the computer being too slow (a stock 9600,too many tracks,or incorrect settings)I managed to finish the sessions but
only after much frustrating resets..thanks in advance... PD

[Rail Jon Rogut]

Why the Printer port and not the DigiSerial port? The latter is preferred.

Rail

------------------
Recording Engineer

[Ask Otis]

I did a project last year, for about 3 months using the exact setup you describe , and in the exact manner you describe. I had the same exact problem you had, although usually it only happened once a day or less. The fix for me was to turn off the USD, while still in protools. PT would then say "lost communication with USD". Turn back on the USD and select it from peripherals and everything would be fine. Since we started using Beige G3 there have been no problems but we are also connected to the DigiSerial port. Not sure which one was the fix.

Hi Peter,

Rail Jon Rogut is correct in his statement that the Digiserial port is a more stable connection. I would move your USD over to the digiserial port on your core card.

What is the firmware set to on your USD and what version of ProTools are you using? The USD unit shipped for a long time with firmware version 3.12. I'm not sure what version the unit is currenty shipping with but for ProTools 5.01 you need to update the firmware to 5.01. You can determine firmware version when you power up the USD. On power up it will display "code 3.12". If this is the case then you need to enable the USD setup button in the Peripherals window. It should walk you through the process. You might consider going through this process regardless just for good measure.

Trash the Digisetup file, the DAE Prefs folder and the ProTools v5.0 preferences file. These are all located in the Preferences folder in the System folder. Empty the trash and restart the computer.

What you are describing is a classic symptom of irregular time code originating from your analog tape. The USD actually "learns" what your time code is doing and then sets its own internal tracking mechanism to follow this pattern. If the pattern is interrupted it has to start all over again but if the time code is irregular on a regular basis ;-) then it will not have a chance to do this. If you have another reel of tape with a fresh time code track I would try syncing to that just to see if ProTools is able to lock.

Later
Oater



[This message has been edited by oatbran (edited February 16, 2001).]

[PeterD]

[QUOTE]Originally posted by oatbran:
[B]Hi Peter,

Rail Jon Rogut is correct in his statement that the Digiserial port is a more stable connection. I would move your USD over to the digiserial port on your core card.

What is the firmware set to on your USD and what version of ProTools are you using? The USD unit shipped for a long time with firmware version 3.12. I'm not sure what version the unit is currenty shipping with but for ProTools 5.01 you need to update the firmware to 5.01. You can determine firmware version when you power up the USD. On power up it will display "code 3.12". If this is the case then you need to enable the USD setup button in the Peripherals window. It should walk you through the process. You might consider going through this process regardless just for good measure.

Trash the Digisetup file, the DAE Prefs folder and the ProTools v5.0 preferences file. These are all located in the Preferences folder in the System folder. Empty the trash and restart the computer.

What you are describing is a classic symptom of irregular time code originating from your analog tape. The USD actually "learns" what your time code is doing and then sets its own internal tracking mechanism to follow this pattern. If the pattern is interrupted it has to start all over again but if the time code is irregular on a regular basis ;-) then it will not have a chance to do this. If you have another reel of tape with a fresh time code track I would try syncing to that just to see if ProTools is able to lock.

Thanks to Rail,Ask Otis and Oatbran for helpful advice.I will recheck the firmware on the USD even though it appeared never to lose sync(the TC numbers kept right on advancing even after Protools lost sync and stalled)The one thing I did notice was that the Yellow USD indicator was constantly flashing which I took to mean the USD was constantly adjusting itself to the incoming linear TC.Under ideal circumstances(when locked internally or to house sync )this yellow light remains solid of course)Am I incorrect in assuming this flashing to be normal!! thanks again PeterD

[Ask Otis]

Attention!!!!

"Under ideal
circumstances(when locked internally or to house sync )this yellow light remains solid of course)Am I incorrect in assuming this flashing
to be normal!!"

If you are resolving to incoming LTC (clock source = LTC) and the light is flashing you are NOT accurately locked, and your PT will drift compared to the Analog tape. You must have solid yellow light in order to reliably lock. This is very important and has screwed me before.

Slow flashing means the incoming LTC is to slow, fast flashing neans to fast. Usually a varispeed from (for example) 30ips to 30.01ips is all the correction neaded.

[PeterD]

Originally posted by Ask Otis:
Attention!!!!

"Under ideal
circumstances(when locked internally or to house sync )this yellow light remains solid of course)Am I incorrect in assuming this flashing
to be normal!!"

If you are resolving to incoming LTC (clock source = LTC) and the light is flashing you are NOT accurately locked, and your PT will drift compared to the Analog tape. You must have solid yellow light in order to reliably lock. This is very important and has screwed me before.

Slow flashing means the incoming LTC is to slow, fast flashing neans to fast. Usually a varispeed from (for example) 30ips to 30.01ips is all the correction neaded.

Dear Ask Otis,
Thanks again for your insight ..are you sure about this ??The analog tape was striped the same day from the USD on the very same machine that was causing the trouble, so I would assume motor speed would have remained fairly constant (unlike moving from machine to machine).My understanding was that because the 24 track is freewheeling ,the speed fluctuations would be significantly wider than those associated with a 24 track under synchronizer control...hence the USD's yellow light constant flashing.This is in fact the third occasion I have had this kind of thing happen and interestingly enough it seems the more powerful and faster the computer, the less of a problem it is!
Still I will certainly try your suggestion and thanks again PeterD

[KSutton]

I'm sure you tried this but, in the session set up window where the protools freewheel setting is located (on mine usually set to 8 frames) have you tried increasing that? I've had trouble with Pro-tools dropping out when locked to a digi-beta & my system is locked to the same house sync as the VTR. This is with clock source on video & positional reference on LTC. Just a thought. I've increaed it to 15 frames & locks fine (lips look good) good luck.

Karl

[Rob Macomber]

I have always followed one rule when slaving PT to anything. COMMON SPEED REFERENCE. If you do not have a common speed reference for all devices in the scenario...you can possibly expect sync problems. Using LTC from the master as speed reference can be shakey. Only if the master has a rock solid motor and the PT system is beefy ( cpu speed + 10000 rpm drives+ RAM + low track and edit count) will you remain in sync..MOST of the time.( for short periods ) Who wants marginal reliability?? One should always use word clock or blackburst as master speed reference and LTC/VITC as positional reference. THIS IS SO Important because PT works from a SMPTE trigger. If You start at the same time, but the speed slightly changes..Ba da bing...outta sync. How can you ever expect to be at the same location at the same time??

Another thing...The Printer Port Sucks for timing issues.....Obviously the Digi Serial port is the port to use for serial Time code...and second to that the modem port....never the Printer.

ALSO...when trashing the DIGISETUP pref.....You must shut down the computer for 30 seconds or so....then start up. Choosing restart does not reset the digisetup prefs. If you do not get the prompt to choose an audio interface upon launching PT again...you did not properly trash the digisetup file.

[evandaum]

I agree with the last part of that statement, but I've NEVER found that trashing the Digisetup, emptying the trash and rebooting failed to get me the setup prompt upon re-launching. Shutting down and waiting 30 seconds seems like voodoo to me.

-Evan


ALSO...when trashing the DIGISETUP pref.....You must shut down the computer for 30 seconds or so....then start up. Choosing restart does not reset the digisetup prefs. If you do not get the prompt to choose an audio interface upon launching PT again...you did not properly trash the digisetup file.