Sync HD drifts and stutters

[evan.jerred]

Hi, I've recently added HDX, Sync HD, MTRX Studio and AJA Gen 10 to my studio to achieve genlock video. I have everything hooked up right, all indicators show everything is locked and set correctly, but my sync drifts over a half frame while working, and I get frequent ~1 second pauses/hangs especially just after scrubbing. I suspect the Sync HD or possibly the aftermarket serial cable I got on ebay, although it shows up fine in Digitest and PT, takes firmware "updates" (2.2.1) and I'm not having any dropouts or loss of connection to the Sync HD, at least not any that are indicated. It just doesn't work right. Cases are open and logs are sent to Avid, but progress is slow and I'm curious if anyone has any thoughts. I've tested two different computers running Ventura and Sonoma, PT 2023.12.1-2024.3.1, two different video peripherals (AJA IoXT and BM Ultrastudio HD Mini) with multiple drivers for each. Trashed prefs, reset Sync HD, gave it more room to breathe in my rack. Different sessions, blank sessions, different framerates, native and rosetta. No changes. The system runs smoother and in better sync with the Sync HD disabled and running standalone than when it's enabled. Not ideal!

[Frank Kruse]

0.5 frames of drift over what timespan? After 90minutes of continuous playback?

Does the video card driver indicate that the correct clock is present (in the driver panel) and is it set to genlock to video-ref in the AJA panel?

[evan.jerred]

I could leave the system idle for 20 mins and my sync reading will be a few ms off. It just drifts constantly while working. I am resyncing the system (sync one2+time adjuster on my master) throughout the day. I’m on the Blackmagic card now but yes both cards software showed lock to incoming vid ref matching the session and video. As do the Sync settings in Pro Tools.

[Frank Kruse]

Still not sure if we're both using "drift" in the same way. In my world "drift" means you hit play and over time while playing continuously the sync of video and audio drift apart (sync gets worse more and more the longer you continue to play without stopping). Not sure if you mean "playing" when you say "20 minutes idle".

[evan.jerred]

Sure, we could say the sync slips, or moves. It just doesn’t stay in sync during use. When I say idle I mean I can set the sync, walk away and come back 30 mins later and it won’t be in sync any more. Or I can edit for half an hour and it won’t be in sync any more. It doesn’t seem to be dependent on anything, it’s just moving around.

[Frank Kruse]

"walk away" and PT keeps playing forward or what does walk away mean? "during use" means continuous play?

Trying to understand if what you mean is actually a varying offset but once it plays it doesn't drift, it just keep playing with the fixed offset but no actual drift.

As in: I hit play and stop 10 times and the offset is different every time.

or

I hit play (it's in sync) and let it play for 20 min (no stopping) and then it's not sync anymore?

Remember that PT switches to a different playback mode when looping so I'm not sure if looping over a 10 minute segment is supported to maintain sync (regardless or being genlocked or not).

AFAI, genlock interlocks when playing. Not sure if it does it when looping.

[original_min]

Sorry to hear about your hassles, a few quick thoughts..

Are the dip switches on the AJA Gen 10 set correctly?
Is the video playing at the right frame rate and without any errors?
Have you changed out the LoopSync and/or SyncHD cables at all?

[evan.jerred]

The dip switches are good. Sync HD and vid card shows lock in 23.98 and 24 sessions (after changing the rate of the Gen 10). As for the BNC cables, they are brand new and I’ve tried both loop sync and word clock between the Sync HD and MTRX studio with the same results. Video plays fine, but has some stuttering when stopping and starting while the Sync HD is active but that smooths out when I disable Sync HD in peripherals.

[evan.jerred]

Update regarding sync slop:

After trying 2 Sync HDs, 1 Sync X, HDX, HDnTB, AJA GEN10, BM Mini Sync Generator, Mac Studio M1 Max, MacBook Pro M1 Pro, AJA IOXT, BM Ultrastudio Mini HD, every combination of cables and settings imaginable... It seems my TV was at fault.

I tried 4 different Samsung TVs. 2 QLEDs (Q80T, QN95B) and 1 OLED (S92D) didn't work, but one older NU6900 worked after turning all it's processing off. That is to say it held perfect sync for over an hour, the same with two different sync ref gens (with other displays different sync ref gens resulted in different speed of slop, I guess because the TVs take in the frames at one rate, and then display them at their own internal clock frequency). I also tried recording the video and audio (of my Sync One2 test file playing in Pro Tools) into a video card and everything was sample accurate in sync. So the good news is 100% of the gear I used worked fine as far as I can tell. Bad news, after ordering the S92D and it not working, I've decided to give up for the time being. At least I know all my gear works and I can sell the extras.

As for pausing and stuttering while doing fast paced editing and using a sync peripheral, working with Avid has resulted in better performance, but still not as smooth as turning the sync peripheral off or working with it on but in running PT in Rosetta. Performance was the same for Sync X and Sync HD, as well as HDX and HDnTB. I'll be continuing to test this with them.

I'm really curious to hear what displays people are using with their genlocked systems that don't slop... beware of newer/high end Samsungs. If I ever get the chance to test with Sony or LG displays I will but I've had enough testing for now to say the least.