Possible SMPTE generator issue

Hi all,

I just had a problem pop up that may or may not be associated with the Nuendo SMPTE generator plug in.

I used the plug in to create several SMPTE stripes for our video guys.

These stripes are 30fps. The wavs are 48/24.

Each stripe, once it starts, is continuous time.

I just got a report of three times where the SMPTE jumps out of time and then back over the course of about 3-5 frames. Although for the moment I can’t report down to the frame level, I’ll give you the actual times since they may be indicative of a problem:

hrs min secs
03 37 38
03 57 38
03 57 58

I’ve been told there have been other pops but I’m still waiting to get more times. The second and third times are in the same stripe, but the first time is in a separate stripe.

We were able to film the timecode and watch it back in slo-mo to see what was happening. For the first time listed above we saw the time code jump ahead to somewhere in hour 7 then back to hour 4 then it resumed as normal.

Has anyone seen anything like this before? The similarities in times regarding the numbers 3, 5, 7 and 8 seems very suspect to me. We have a SMPTE conditioner reading the SMPTE from Nuendo then resending it to the video playback system but, through testing, we’ve figured that the problem has to lie with either the Nuendo generator or the video system itself. Unless someone else has an idea of another culprit.

Any ideas?


Darren “SMPTE” Ingram

OK, we’ve tested the stripe on two other machines and can’t replicate the issue that our video playback system is having. BTW, we’re using Coolux for media projection.

Is there any way that the Nuendo generator could print SMPTE in such a way as to cause problems on just one reader and not another? Is there any kind of math something involved that could cause problem - like a format issue?

I just need to exhaust all possibilities on my end before shifting the focus to the reader.


Darren “Focus Shift” Ingram

If you are using a digital audio channel to output timecode and record it elsewhere, there are chances that you could end up with phase problems because of interferences between the digital audio sampling frequency and the timecode spectral and phase content. A SMPTE timecode is a difficult signal for a digital system at 44.1 or 48 KHz.

This is the reason why we did use in the past a dedicated analog track on some well known digital audio tape machines to circumvent this problem causing jumping or difficult to read timecodes.

Do you have a master video sync device and did you sync Nuendo to this signal ?

If you could avoid using this method of copying the TC as an audio signal it would be better.

Could you try to stripe a TC directly with your video system, then synchronize the video recorder to Nuendo to later copy the Nuendo audio tracks ?

We have been using the SMPTE generator to sync other machines for a long time, but I must admit that it has been a while now. (Except for setting up remote links for Audio Post Sync which worked well)

For the record, we never-ever had any problems with it. Not saying that there can’t be any right now.

But the list of possible problems is endless.
Just a few things that come to mind:

-SMPTE readers are very sensitive to the level of the SMPTE stream, so you should play with the levels a bit.
-Sure there is no spill from another channel/source at those “error” places.
-Are the systems clocked to the same House clock? (video reference)
-Frame reference vs clock reference?
-What are the error reading settings on the slave machine? (Dropout frames & inhibit restart)
-Try Jam Sync?

Etc …