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Pro Tools Ultimate/Sync HD/Blackmagic video issues
Old 7th October 2019
  #1
Pro Tools Ultimate/Sync HD/Blackmagic video issues

Hey everyone,

I am relatively new to the world of video tech, and am having some slightly peculiar issues on my Pro Tools HDX system. I am running it with a Sync HD - currently it is clocked to LTC and set to the master in Pro Tools sessions. It is also tied in with loop sync to my Avid Omni. Video is playing back via a Blackmagic Intensity PCIe card (not the most recent 4k version, but essentially the same layout).

A couple of things I'm experiencing:

- Online video (both Safari and Chrome) and often video files that are launched in Quicktime (work in progress stuff, etc) don't playback at the correct speed. They zoom through in a matter of seconds regardless of the video length.

- Sound to frame sync still seems like a bit of an issue in Pro Tools. It is a little bit sloppy, changing between plays.

Any idea on what might be going on? Jamming to LTC was a quick roll of the dice on my behalf to perhaps sort out the issues in Quicktime/Safari/Chrome/OSX. Unfortunately the Intensity PCIe card is pretty simple, and doesn't have LTC or Reference I/O at all. Could it be a buggy Blackmagic driver that is causing the issues in OSX?

As far as obtaining stable sync, my brother is mailing me a spare Blackmagic Decklink Extreme card to try which will allow me to jam the whole system together in a number of ways (word clock, LTC, Ref video, etc). Is grabbing a Tri-level sync generator the best way to go? Or will splitting the SDI output of the Blackmagic card and feeding it to the Sync HD's video reference input offer similar sync stability?

All this video stuff is a new world to me, and it is a wee bit daunting so if you have any tips that would be terrific. The end game is a system that is frame accurate for synchronising sound effects, foley and dialogue.
Old 7th October 2019
  #2
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You got that a bit wrong in your head I think. You don't need to feed LTC to the Sync IO in your case, the box is generating it.

Best practice in your case would be to get a video ref generator and feed it both to the Sync IO and the Blackmagic card.

Forget about LTC in that case. It's for _positional_ reference, not sync.
Old 7th October 2019
  #3
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Quote:
Originally Posted by LDStudios View Post

All this video stuff is a new world to me, and it is a wee bit daunting so if you have any tips that would be terrific. The end game is a system that is frame accurate for synchronising sound effects, foley and dialogue.
Yep, you'll need a different video card. One that can be gen-locked and has a video ref input like the Decklink cards or other. You also need a tri-level sync generator and then clock the SYNC HD and the video card to the same common sync signal. Only then you will have dead on sync-lock every time you hit play and no drift over time. Also you will need to check the overall sync offset and dial that into the video sync offset setting inside PT to compensate for the latency of your video signal chain incl your monitor/projector. Without this setup you'll get a start error of +- 1 frame at best (and sometimes more) and your playback will drift over longer playbacks.
Old 7th October 2019
  #4
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Is it really that complicated in PT world?

I’m running Nuendo in a Mac cheese grater, with an Intensity card. Ancient MOTU 2408/III. I have a Rosendahl Nano as my common AES and black burst clock, but that’s only because there’s other syncable stuff in the rack. Without it, I could use the MOTU as my master clock. No tri-level, no LTC.

Sync is rock-steady at any common rate (including 23.98, etc)... including dynamic offset to compensate for Intensity>HDMI, video router, and 65” pix monitor... which is in ms so it doesn’t care about frame rate. A tiny bit rubbery when I’m playing at .5x or .25x to check placements, but then you’re dealing with fractional frames.
Old 7th October 2019
  #5
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Quote:
Originally Posted by Jay Rose View Post
Is it really that complicated in PT world?

I’m running Nuendo in a Mac cheese grater, with an Intensity card. Ancient MOTU 2408/III. I have a Rosendahl Nano as my common AES and black burst clock, but that’s only because there’s other syncable stuff in the rack. Without it, I could use the MOTU as my master clock. No tri-level, no LTC.

Sync is rock-steady at any common rate (including 23.98, etc)... including dynamic offset to compensate for Intensity>HDMI, video router, and 65” pix monitor... which is in ms so it doesn’t care about frame rate. A tiny bit rubbery when I’m playing at .5x or .25x to check placements, but then you’re dealing with fractional frames.
Well, you can't lock 24P or 23.98 video the the edges of SD NTSC black-burst. You'll need a clock that has a "grid" that is the same format as the video you want to sync.
Has nothing to do with PT. Any two devices in a studio will need a common clock to resolve to otherwise each one of them will just free-wheel with it's internal clock.
Old 7th October 2019
  #6
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Quote:
Originally Posted by apple-q View Post
Well, you can't lock 24P or 23.98 video the the edges of SD NTSC black-burst. You'll need a clock that has a "grid" that is the same format as the video you want to sync.
Has nothing to do with PT....

Nice to know what I'm doing is impossible.

Late last week, I reviewed a 2+ hour 23.98 feature with the producer and director, top to bottom with no stops. No drift. Tons of individual clips (ranging from two-word dialog, to 4+ minute music cues, to 20 minute reel predubs): They all played at the right time, kept their relationship with other clips, and held through their length. Even added on-the-fly BITC at 23.98 for our notes.

Good DAWs since the mid-1990s* have been tracking their "grid" as absolute samples from zero, translating to the current timecode format on the fly. Want to change NDF to DF to film? No problem. Clips will still have the exact same relationship to each other, and play at the same speed. You just have to find a new starting offset, since the 2-pop's number of video frames since midnight will have shifted relative to the number of samples since zero.

Since the Intensity and Nuendo are in the same computer, Intensity looks at Nuendo... which looks at the word clock being generated locally by MOTO, or regenerated by MOTU based on the Nanosyncs word clock. Needless to say, that clock's at 48 kHz. This s/r doesn't change depending on the frame rate or counting system. It might be pulled up or down if there's an FXR involved, but that's to make an intentional speed change... not to change any 'grid'.

Since last week's film had been shot 23.98, there was no pulldown. Just pure 48kHz wordclock, or 29.97 SD black. Having my house black at 29.97 MAKES NO DIFFERENCE to the production, whether it's this one or something at 24 or 29.97 ND or 29.97 DF. It's phase-locked to 48 kHz by the MOTU, and that's all Nuendo looks at.

Back when I had separate devices (BSP and Doremi, plus TC DAT and DA98), they also got wordclock from the Nanosyncs. And FWIW were steered around by P2 commands, rather than LTC. But now that everything is tapeless and lives in the host, even that's not needed any more.

-----
* - I designed the P2/Chase/Sync behavior on the Orban DAW back then, with Dr Barry Blesser as project leader.

It was pretty radical at its time: 'traditional' engineers would tell me it was impossible to slave video to audio without glitches.

I'd then drive a BSP deck from our DAW's controller, not only playing in perfect sync with DAW as master, but also scrubbing randomly through the audio... and seeing the video turn over frame-by-frame, like it would on a Steenback at slow speed. The only connections were RS-422 plus blackburst via coax.

But I know that even today, a lot of NLEs are locked into a frame-by-frame orientation. So it's possible some DAWs are still thinking that way as well.

Last edited by Jay Rose; 7th October 2019 at 10:43 PM..
Old 8th October 2019
  #7
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Quote:
Originally Posted by apple-q View Post
Well, you can't lock 24P or 23.98 video the the edges of SD NTSC black-burst. You'll need a clock that has a "grid" that is the same format as the video you want to sync.
Has nothing to do with PT. Any two devices in a studio will need a common clock to resolve to otherwise each one of them will just free-wheel with it's internal clock.
While that's technically correct, we also don't experience any sync/drift issues with feeding SD PAL black-burst to both the video card and the Sync HD.
Old 8th October 2019
  #8
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Quote:
Originally Posted by kosmokrator View Post
While that's technically correct, we also don't experience any sync/drift issues with feeding SD PAL black-burst to both the video card and the Sync HD.
I can assure you that the BM cards will NOT lock to a video ref signal that is of a different format than the video format that's playing. You can see that in the BM driver panel when you feed SD BB sync to the card when you have an HD format picture playing. PT can lock to slow PAL and has other options to tie into setups that do not have HD clock sources but the BM card will not lock to that. And there are sync boxes that can generate sync BB and TriLevel signals that resolve to the same internal crystal reference but the video card itself won't lock a 24fps picture stream to a 25fps BB signal. It's like trying to play 24 drum strokes a second accurately to a conductor swinging his baton 25 times a second.
It will obviously still play and seem "OK" but it won't be 100% sync every time you hit play.

to Jay: well syncing to wordclock is perfectly fine for audio devices but a video hardware needs edge-sync from a video clock and the intensity card can not be resolved to an external clock period. It will send out frames at it's own "convenience".
There's a reason why these cards have video ref ins.

Whether sync is "good enough" for your purpose is a personal decision but unless you've measured picture sync with a SynCheck or SyncOne2 you'll never know.

But don't take my word for it. Measure it. Also this:

https://non-lethal-applications.com/...ocked-playback
Old 8th October 2019
  #9
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Quote:
Originally Posted by LDStudios View Post
A couple of things I'm experiencing:

- Online video (both Safari and Chrome) and often video files that are launched in Quicktime (work in progress stuff, etc) don't playback at the correct speed. They zoom through in a matter of seconds regardless of the video length.

- Sound to frame sync still seems like a bit of an issue in Pro Tools. It is a little bit sloppy, changing between plays.
Seems to me that those are two distinctly different issues.

What video file format are you using in PT? If I remember correctly some are good and some aren't. For correct sync you shouldn't use H.264 for example (again, if memory serves me).

The former seems like a different problem....
Old 8th October 2019
  #10
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Intensity sends out video frames as they're delivered from the video engine in the DAW. It's completely repeatable. Once you've calibrated for the card's (and monitor/projector's) delay at play speed, the frames appear at the precise rate the DAW is calling for them.

Intensity doesn't read the video file directly. It's not like a Beta deck, getting a start command and then dropping to house sync once it's slewed. It displays frames coming from the DAW... which is why you can play at 1/2 or 1/4 speed -- or backwards at fractional speeds -- and have pix keep up.

If frame edges coming from the DAW don't line up with frame edges as computed by samples-from-zero (once you've adjusted dynamic offset), it's the DAW's fault. Not the sync reference's.

Of course my clients and I are only interested in sub-perf accuracy. We're not that particular about whether the playback might be a nanosecond or two off. Heck, we don't even measure the distance from the mains to the client, plus the ambient temperature, and compensate for that delay.
Old 9th October 2019
  #11
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I just checked the docs for Intensity's SDK. It seems it can be run either as a synchronous player, or as a one-frame-per-command at video rates. I can't see why a DAW designer would want to use the former arrangement...
Old 9th October 2019
  #12
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That's all great in theory. Unless you measure the result I'll take it with a grain of salt. I stand by what I said in response to the OP.
There's a reason why these cards have gen-lock inputs and no professional studio out there that I know runs their mix stages without a fully gen-locked setup.
And I won't start nudging clips around because they look out of sync without knowing my rig is bang on in terms of sync. How do I know? Because I make sure with a SynCheck at mixing position and every (professional) mixing theatre I've been to does this as well before every mix. There are way too many interlocked machines (DAWs, projectors, monitors, converters etc. etc.) working together just to rely on some theory that things "should" be sync.

Last edited by apple-q; 9th October 2019 at 09:59 AM..
Old 9th October 2019
  #13
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Apple-q, we're not really in disagreement.

When I was running a multi-machine room, everybody was synced to either blackburst or word clock, both coming from the same generator. It was the only way to make things work reliably.

About six years ago, I switched to totally in-the-box, using a DAW that also handled locked video (with the Intensity card). No tape, Doremi, VVTR...
I kept the sync generator because I have a couple of other rack pieces still, but the computer/DAW/Intensity all resolve to one point. It works, repeatably, to much better than one-perf / quarter-frame resolution.

Please don't impugn my quality (Whether sync is "good enough" for your purpose is a personal decision...). We've got different kinds of setups, but I'm assuming we're both serious professionals.

Neither one of us knows what the OP is using.
Old 9th October 2019
  #14
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Quote:
Originally Posted by Jay Rose View Post
Neither one of us knows what the OP is using.
No worries.
He pretty precisely described what he's using (HDX, SYNC HD, Intensity) and that sync is rubbery in a different way each time he hits play (the LTC part I didn't really understand but it doesn't really make a difference). Why that happens is in that article I posted and it's also mentioned in one of the PT manuals (either the sync HD or the main one).
Old 9th October 2019
  #15
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Then we're back to where we started, almost:

1) Either Nuendo handles this kind of thing better than PT*...

2) Or there's something funky about his setup, that can't be blamed on the software, Intensity card, and Digi sync box he's using.

--
* Please don't imply I'm somehow missing "rubbery, inconsistent" sync. Even if I showed up for all my sessions stoned, my clients would surely notice.

There are fundamentally different architectures underlying PT and Nuendo. PT grew out of Digi's 1989 software, and has always had to consider upward compatibility because of its large installed base. Nuendo was a completely different approach, introduced in 2000. Not saying one is technically better than the other; these days, they're both about the same capability (and cost for a full system). Each introduces new features that appear in the other a year or so later.

You can't assume that just because something is true in one, it'll be true in the other. Hence my original question.
Old 9th October 2019
  #16
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Jamie Mac's Avatar
I have ditched my hdx and sync hd a while ago.
Recent blackmagic drivers and pro tools updates give you excellent and stable sync, making the sync hd unnecessary for me.

Maybe I’m just unsensitive to sub frame sync, but I’ve never had anyone mention it since I changed my setup.
Old 9th October 2019
  #17
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So Jamie, are you using any external sync generator?
Old 10th October 2019
  #18
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I come from the caves, where I had to sync a U Matic VTR to reel to reel tape machines and I was a happy man then.

So now, in 2019, I wonder why if using PT, do I need to have a Sync HD, a video card with ref in, plus an external sync generator in order to get accurate sync from a video that is played on the same timeline as the audio!

Worst than that, if I need to have LTC out of PT to feed, say, a Dolby RMU, I also need (guess what) a Sync HD. For outputing something simple as LTC? Really?

Well, I understand that is desirable to have a sync generator that can resolve and output word clock and black burst (even trilevel) at the same time, so that you can simultaneously feed both you converters WC input and other digital audio gear and also the video ref on the video card.

If Nuendo and others can do it, I guess that AVID can do it too. A lot of the functions on the Sync HD, like controlling of video decks, RS 232/422 etc are outdated now, so why do people have to pay for things they are not going to use? I´m not bashing PT, I use whatever DAW that does the job I want, but I can understand Jay´s point:

"Of course my clients and I are only interested in sub-perf accuracy. We're not that particular about whether the playback might be a nanosecond or two off. Heck, we don't even measure the distance from the mains to the client, plus the ambient temperature, and compensate for that delay."

You made me smile when I read that, I´m also a bit fed-up of nano frame accuracy eheheh, to be honest, I can´t spot a quarter frame out and I really don´t care.
Old 10th October 2019
  #19
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. A lot of the functions on the Sync HD, like controlling of video decks, RS 232/422 etc are outdated now....

Back when I had to worry about tape and Doremi, RS422 with full edit commands with Nuendo was just a question of a $30 USB adapter. And LTC just meant inserting Nuendo’s TC generator in a parch point of convenient audio output channel. The point is, Nuendo and PT are very different. You can’t assume because something’s true in one, that it’s universal.
Old 10th October 2019
  #20
Quote:
Originally Posted by paulo m View Post
I come from the caves, where I had to sync a U Matic VTR to reel to reel tape machines and I was a happy man then...
Worst than that, if I need to have LTC out of PT to feed, say, a Dolby RMU, I also need (guess what) a Sync HD. For outputing something simple as LTC? Really?
I come from the caves too then, but wouldn't like to go back to flying in sfx from a 2track or sampler to a multitrack synced to a VTR, making a big track sheet on A3 paper building the sound edit :-)

A couple of things I noticed through the years. We have 3 Sync HDs and distribute sync from a Rosendahl. I always found the Sync I/O and HDs to be one of the poorly designed pieces of Avid/Digidesign hardware...it had RS422 but they encouraged you to use the serial port of the Mac instead because of possible issues with the RS422 on the Sync interface. Really? Timecode generation from the Sync boxes was also something I never really trusted. We talk about A/V sync in this thread, but I often wondered if the TC generator in the Sync was sample accurate with PT on multiple playbacks, so stopped using it. Also it didn't loop TC, when PT was in loop. Kind of useless. So back when we were using Bonsai drives for SD video (because the QT DV via Canopus boxes was terribly unreliable sync wise), we put LTC on an audio track in PT and used that to drive the Bonsai; it was sample-accurate LTC and looped the picture in ADR loop-record situations. You just had to leave an empty track in PT besides the LTC track to avoid TC crosstalk (2" 24track habit that never died :-)

When Avid introduced the Avid Video engine, QT sync got a lot better. It took some years and you have to find the right Blackmagic driver to make it work :-), but nowadays video stays sync even without distributing tri-level. In another studio we have a DAD AX32 on one PT system acting as master and distributing word clock to all necessary interfaces, convertors and PT systems and everything stays sync (which a DAW should be able to do, as Jay rightfully said).

Greetings,

Thierry
Old 10th October 2019
  #21
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Jamie Mac's Avatar
I’m not using any sync generator. Just my computer, interface and a decklink sdi.

It works perfectly in sync without AVID’s and other sync hardware.

The days when they were necessary are absolutely gone. The reliability of video sync in protools has changed over the last few years.

You don’t have to believe me, but I’ve tested the various setups in my studio and concluded that I should sell the sync hd, because it is a very expensive piece of kit that serves me no benefit anymore.
Old 10th October 2019
  #22
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It's not only about staying sync and I did mention that WC is perfectly fine for that. It's mainly about when picture and sound start playing. You don't want your 2-pops +- a frame around the sync mark. Even if it doesn't drift after that it will stay offset. And I'm not talking about "nano-frames". Such things can only be said by people who have never tried a SynCheck on their rigs and simply rely on "client didn't complain so it must be accurate"-method. Nowadays even single device has a latency.

I'm also not here to defend or bash PT let alone discuss a Nuendo/PT DAW-war. I came here to give the OP a hint about how to improve what he's seeing and the technicalities behind it and things drift off to a "Nuendo is much better"-argument.

I've nothing more to add.,..
Old 10th October 2019
  #23
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nixt's Avatar
I think without a sync the most important thing is to always use the same video codec and format. Preferably DNX HD or Pro Res. From one codec to another the delay compensation will be very different. Compressed codecs such as H264 cannot be used reliably with Pro Tools.
I gave up on blackmagic a while ago because their drivers were giving me headaches and the sync with Pro Tools was not reliable. Maybe they fixed it since but I'm super happy with my AJA cards (found for a very reasonable price on ebay).
Old 10th October 2019
  #24
First of all, the QT sync problem in PT, the way I see it, has to do with repeatability, at least that's what is always bothering me when working on a non-resolved system.
From my experience (and I don't have any scientific knowlege to back this up) whenever one starts a playback on a non-resolved machine, it will lock to the picture at a different point. So I may watch the playback once and feel it is in perfect sync, next time it may look different to me. No guarantee at all. Checking the pop sync mark (which many of us don't use any more because everything is "digital" and therefore "in sync") with Syncheck, I can confirm this randomness.
On a locked system, that simply does not happen, and that is why I have my studios resolved to video. It is a bit of a nuisance having to check the video standard every time you open a different session (in Europe it is a nightmare!), but once you get used, it really pays back.

Quote:
Originally Posted by thierryd View Post
Timecode generation from the Sync boxes was also something I never really trusted.
Thierry, I can assure you the LTC generator (when resolved to WC or Video) is very stable, and in perfect sync. In my mixing studio, Dolby RMU uses LTC as a positional reference. That LTC is generated by SYNC HD, and I get the same result every time I check the 2-pop in the RMU viewer, after recording the Print Master. The offset in my setup is 1 sample, constantly.
Old 10th October 2019
  #25
Quote:
Originally Posted by Branko View Post
First of all, the QT sync problem in PT, the way I see it, has to do with repeatability, at least that's what is always bothering me when working on a non-resolved system...
Thierry, I can assure you the LTC generator (when resolved to WC or Video) is very stable, and in perfect sync. In my mixing studio, Dolby RMU uses LTC as a positional reference. That LTC is generated by SYNC HD, and I get the same result every time I check the 2-pop in the RMU viewer, after recording the Print Master. The offset in my setup is 1 sample, constantly.
Hi Branko, true about the repeatability. I just checked my setup here this morning (2PT systems, all word clocked to AX32, 2nd PT system runs video, sync via satellite). With Catchin sync the sync is constant with every playback start. When short looping a big mix around the beep, sometimes there is a quarter frame offset between 2 playbacks in a loop (but then this test pushes things a little bit :-)
Resolving to tri-level is of course still a good idea, but in my experience it just works rather well without it. I started testing this, as we often switch between sessions (25, 24, 29.97fps) and then you constantly need to adapt the resolving as well, which is a pain :-)
Checking the pop sync mark should be standard practice indeed and I often have to ask the video department to include start and end pops as it is becoming a lost art :-)
The LTC generator issues I had were somewhere between 2001 and 2007, which made me change to the LTC on audio track and I never changed that habit again. Also the looping issue is still current I think, as I suspect the LTC is generated in PT from the same "source" as MTC and that didn't loop either... Putting LTC on an audio track if needed just works fast and reliably. You can generate any LTC you need here for example: http://elteesee.pehrhovey.net
Sometimes the simpler/older ideas just work better... ;-)

Greetings,

Thierry
Old 10th October 2019
  #26
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Quote:
Originally Posted by thierryd View Post
The LTC generator issues I had were somewhere between 2001 and 2007, which made me change to the LTC on audio track and I never changed that habit again.
I'm surprised to hear that in the times of Satellite. You chase and loop your rigs via LTC?
Old 10th October 2019
  #27
Quote:
Originally Posted by apple-q View Post
I'm surprised to hear that in the times of Satellite. You chase and loop your rigs via LTC?
No, as I explained above, I'm using Satellite with all systems locked to word clock. No LTC or Tri-level resolving anymore. LTC is not often needed anymore in sound post setups, but as Branko mentioned, the Dolby RMU is an exception.
When doing production sound LTC is important of course, to sync with camera, digislate etc.

Greetings,

Thierry
Old 10th October 2019
  #28
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Quote:
Originally Posted by thierryd View Post
No, as I explained above, I'm using Satellite with all systems locked to word clock. No LTC or Tri-level resolving anymore. LTC is not often needed anymore in sound post setups, but as Branko mentioned, the Dolby RMU is an exception.
When doing production sound LTC is important of course, to sync with camera, digislate etc.

Greetings,

Thierry
Ah, right, thanks. Interestingly AVID says in the manual a SYNC HD resolved to video ref is required for every Satellite and master to achieve accurate picture sync across the setup (the audio vs. picture hardware not the audio rings to eachother) but as long as your SynCheck looks fine...
Old 10th October 2019
  #29
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Jamie Mac's Avatar
All the issues described here are issues that I also have had in the past. So I know what you are talking about.

But now (as of PT2018.xx and up, with a good bm driver) they are irrelevant.

It's not about "the client won't notice" the situation is: Nobody can notice.
Old 10th October 2019
  #30
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paulo m's Avatar
 

So, considering all of the above (a lot ) do you guys think that having a generator that simultaneously ouputs word clock to feed your audio converters and black burst to feed the ref input on the videocard, is still a good practice? Despite what DAW you use?
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