The importance of blackburst sync in audio post?

[Chief Technician]

I guess my questions are:
1.- Isn't the sync io box a reliable SMPTE/Word clock generator?

Yes. It is not a blackburst generator.

2.- At this stage (dumping mix to DA-88) is the Black Burst essential or am I screwed?

I wouldn't say you are screwed, though using a blackburst generator is always the more sound (no pun intended) way to do this. I do not know how the Digital Timepiece figures into your setup (I've never used a DTP).

3.- If I need a Black Burst Box at what stage is it essential with most of the above scenario already haven taken place?

Step 1 would have been the ideal place to start using a blackburst generator. Going back to step 1 and repeating everything would not be productive if everything looks and sounds correct (effects on cue, no drifting of the audio, no "why does the pitch of her voice sound different?", etc.).

If you're going to use one from now until completion, based on the info here I would say you only need it for your BetaSP, SYNC I/O, and DA-88. In which case you set the BetaSP to sync to ref (as opposed to input, there's a toggle on the rear of the BVW-75 for this), the SYNC I/O to video ref, and the DA-88 to video. Something else you can do, which will give you a blackburst reference without acquiring a seperate generator is to route the video output of your BetaSP to a DA and then from the DA to the SYNC I/O and the DA-88. The BetaSP will reference an internal sync source (functionally the same as blackburst).

The difference between your setup and Don Barto's (LE with DigiBeta) is that he can sync to the AES/EBU from the DigiBeta, which in turn is sync'd to the deck's internal sync source. Since BetaSP doesn't have AES/EBU, the above scenario would be the best way to do it (short of a dedicated generator).

[Jsalam112]

I appreciate your responses Chief.
Please clearly define DA and or give an example. I'm a caveman.

[vze24x2x]

I guess my questions are:
1.- Isn't the sync io box a reliable SMPTE/Word clock generator?
2.- At this stage (dumping mix to DA-88) is the Black Burst essential or am I screwed?
3.- If I need a Black Burst Box at what stage is it essential with most of the above scenario already haven taken place?

Video Sync (Blackburst) is not the same as Word Clock, which is not the same as SMPTE.
if you're woring on a project that was shot on video, and uses either 29.97 Drop frame or 29.97 Non-drop frame time code, you need a blackburst gerator.
I bought a Horita 6 Output Black Burst Generator/DA (Distribution Amplifier) for $260 at B&H Photo a couple of years ago. works fine. My next question to you would be, are you going to be doing digital transfers to the DA88? if so things get a little more complicated/stupid. Lets assume you will be. Connect an output of your BlackBurst Generator to the Video Ref in of your 192 i/o. select the vid Ref input as the clock master in protools. Connect a TDIF cable from the 192 i/o to the DA88. connect a BNC cable from the 192 word clock out (not from the sync i/o) to the word clock in of the DA88... BUT WAIT!! the essential part of this is to get a BNC 'T' and a 75ohm BNC terminator and terminate the wordclock INPUT of the DA88. The BNC'T' is a little metal thing that has one Male end and two female ends. put the terminator on one of the female ends, connect the BNC Cable coming from the 192 word clock out to the other female end and connect the male end to the back of the DA88.
Don't forget to select the same SMPTE frame rate in the TC menu on the DA88 AND make sure the time code timing compensation is set to DIGITAL. this compnsates for the A/D conversion of the Audio vs Time code.
now go to the Hardware setup in PT's and you can choose the format of the wordclock out to be either the sample rate of the session, or TDIF. Choose TDIF.
Take another output of the Blackburst generator and connect that to your video deck's Ref in.
you will need to take the SMPTE out of the Beta and connect to the Timecode in of the sync i/o. make sure you session start time is earlier than the starting SMPTE time.
The only essential times you NEED the Blackburst generator is when you Transfer the Audio into ProTools for the first time and when you layback the final audio to the master video tape or master DA88 that will be transfered to the master Video tape.
-BK

[Chief Technician]

DA is an abbreviation for distribution amplifier. In the case of a video distribution amplifier, you connect one input to it, such as a blackburst signal, and then you get (in a good DA) buffered outputs (however many your distribution amplifier has). DAs are often referred to by how many outputs they have, so a 1x4 DA has one input and four outputs. Some DAs, such as those from ESE, have gain and EQ controls to tweak the signal if necessary.

Those controls come in handy when there is some kind of a signal loss or degradation. One of my SYNC I/Os would not consistently lock to blackburst, and a video waveform monitor confirmed that the blackburst signal coming from my ESE DA wasn't within spec (which is -20 IRE to +20 IRE, but that's beyond the scope of this topic right now). I then adjusted the gain at the DA to get my blackburst signal within spec and all was well.

The fact that the SYNC I/O wouldn't reliably sync to a blackburst signal out of spec is a testament to how good a device it is. A cheaper device would have had a greater tolerance for out-of-spec signals.

[Jsalam112]

Would a digital dump from PT to the DA-88 be the best way to go?

Does anyone know of a place in the Philly area (besides B&H in NY) that would carrry the Horita black burst box?
I've called a few of the larger pro audio places and no luck.

I did my mix in 5.1 with dialogue in the cente channel, music LF and RF channels with ambient sounds towards the LR and RR channels. I sent a few low end FX to the LFE channel. Some of the reverbs (revibe, 360) are being triggered by front speaker material and I have the reverb panned slightly towards the rear for some dimension. There is the occasional automated FX pan.
I've been using the Waves 360 Mixdown plug on the Master to check my stereo balances as we go along.

[Chief Technician]

Would a digital dump from PT to the DA-88 be the best way to go?

Always.

Does anyone know of a place in the Philly area (besides B&H in NY) that would carrry the Horita black burst box?

No.

[Jsalam112]

I picked up the Horita BSG-50 on Ebay for $125.

[Don Barto]

The closest I will go to not using house black on LE/Mbox is the "indirect" or daisey chained method of borrowing synch from the digital audio outputs of a black referenced deck, as descibed above. In fact, even when I work with Beta SP, I reference Mbox to the digital output of some other digital machine that is not really a direct part of the audio transfer, but that I know is outputing an AES/UBU signal that is referenced to house black -- it's not that I am opposed to buying a $125 BB generator, it's just that this is the only way I can reference my $400 Mbox to house black.

But I wonder: is the $125 burst generator -- that in many cases is itself not being referenced to house black -- any more reliable as a synch reference than my computer's internal clock? I bet not -- either will keep every frame of a 90-minute TV show lined up with picture...but neither will, on its own, provide sample-accurate synchronization in a digital-to-digital transfer -- better to daisey chain whatever is available.

But isn't it just wonderful how you can bounce or otherwise do an "in the box" recording of a 90-minute mix on an internally-referenced LE rig and it synchs up with the show. "How do it know..."

Don "The Synch Nazi" Barto

[vze24x2x]

Black Burst is a specific type of clock, whether it's better or worse than the internal crystal in any other device is irrelevant, it's the timing information (59.94kHz) that you're interested in.
I'm not quite sure what you mean Don, when you say that the Black burst generator isn't refernced to "house black". It IS house black. albiet a smaller house. true Black Burst does not provide sample accurate sync during a digital transfer, Wordclock does, and I would daisy chain as little as possible, (but that's just me). Get a High quality wordclock generator that can be genlocked to black for that purpose. I have an Aardvark in addition to my little Horita BB Generator and the combo works great. botom line, If you're doing audio that needs to be in sync with NTSC video you need to use black burst as your sync source. So jsalam112, you're going about it the right way.
-bk

[Don Barto]

I'm not quite sure what you mean Don, when you say that the Black burst generator isn't refernced to "house black". It IS house black.


I was thinking about how many Black Burst generators themselves have a reference video input. In larger faciiities (and in the real world in general) House Black is more of a concept than a physical reality. As facilities grow and gear is added-on, either on a permanent or on an as-needed basis, it is sometimes more practical to add additional black burst generators...than it is to pray for more dedicated DA feeds. Of course these added-on generators need to be referenced to the original source of House Black, either directly, or by any reliable means available. Some readers may not be aware of this. Simply having a black burst generator doesn't buy you anything at all if it isn't being used in the right way. And aren't I getting a sample accurate digital transfer when I reference pro Tools to a valid in-coming digital audio signal? Just wondering.