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Multicam Freerun TC?


JEsound

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I'm working on coming up with a system to manage sync wirelessly over 2 to 3 cameras and 2 or more audio recorders.

 

A little background: I'm traveling around this summer working as the audio department recording music festivals and performances of various genres (mostly folk/etc). The cameras and the audio recorders have the distinct possibility of being spread somewhat far apart, and should be mobile.

 

Currently, the setup I'm looking at would involve sending TC over Wifi from one central, accurate generator to an iDevice attached to each camera/recorder using Movieslate. From my research, this is the least expensive actually workable solution.

 

Pretending for a moment that the above solution works (and I'm open to suggestions otherwise), here's where things break down. Although I'm not necessarily involved with post-production, it is in my job description to make life easiest for the editors.

 

I'd like to be able to take footage from each camera and recorder, throw it in a NLE, and have everything line up via TC regardless of if the clips are contiguous or not. It seems to me like there should be a way to do this, but I haven't found it yet. A verbose explanation of the problem, better than what I can write, can be read here.

 

To reiterate, if I let TC coming from the central generator free run starting at the beginning at the day, all the recorded media from that day will be stamped with a version of "time-of-day". I cannot, however, find a software solution to interpret multiple cameras and audio streams and place them into one timeline based on that time-of-day stamp.

 

What's worked for you? Thanks for the help.

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You aren't going to like my advice much: I had terrible luck with WiFi TC to i-devices in a concert setting.  You are on a good track with thinking of trying to get TC (and hopefully genlock) to all those cameras and recorders, but for it to actually work reliably in this kind of setting you probably will need to go a little further.  Favorite is TC boxes (Lockit/SBT etc) that make both TC and Trilevel sync for the cameras, are very stable long-term and very reliable.  If you use current pro-type audio recorders (SD, Zax etc ) then the audio will stay in sync with those boxes.  If you use a computer based or other type digital system (like JoeCo) then you need to provide the recorder with word clock and TC in sync with those TC boxes on the cameras.  This is the tried and true way to do this work, the best way I say.   I would strongly suggest looking into rentals for what you need if you can't afford to buy them.  

 

How can you economise on this?  Some cameras you might use won't take external sync (or TC), what then?  What then is that you make more work for post, since all the devices will not stay in dead sync with each other over a day for sure without ext clock, so they will have to resync fairly often, by eye, regardless of your TC, since all the devices are not clocked together (making video frames and audio samples at a locked common rate).  If you can't go with real TC boxes w/ trilevel for the cams for whatever reason, then doing something re TC only will put you in the ball park re sync.  I would lock down the audio sync for sure (pretty easy, really) whatever the recorder is--eliminate one variable.  I would still not try to rely on transmitted TC of any kind for what you are doing: using cheaper (but solid) TC boxes like TIG or Tentacle would be good.  In any case I would strongly recommend getting some audio recorded on the cameras, even if it is just an onboard mic, to use for dailies viewing as well as as a sync ref (re pluraleyes etc).  The cam mic won't be great for this at a concert, but is better than nothing if you have no other way to get audio to the cameras.  Least fave method (but much used) is to either just jam-sync the camera (if that's possible) or get the onboard TC gens to some agreed-on value and then start all the gens (camera and audio) together: what we refer to as "3,2,1,GO" sync.  Rough ball park TC only, no common clock to fix drift, but with onboard audio (and good notes) a fighting chance for editorial to figure out the mess…and it WILL be a mess.   Good luck!

 

p

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What have been the hiccups you've noticed when using Wifi TC? Not that I don't believe you, I just want to understand fully what the limitations are.

 

Second question, a tad toward the n00b side: How important is genlock/trilevel in addition to TC? I understand its application in a live-switch situation, to ensure all cameras capture a frame simultaneously. Am I correct in thinking that regardless of TC sync between cameras, without a common frame clock one camera has the potential to drift out of sync from others, just like two un-synced audio recorders might?

 

We will be certainly capturing the best audio we can on each camera, so we'll always have that as a backup to throw into Pluraleyes. My concerns with audio sync, which very well may be unfounded (and I can't know at this point, because I have little idea of what situations we'll encounter) are:

  • Mobile cameras might be in a location with unclear audio (ex. next to a PA, if there is one), or audio not loud enough for a reliable sync (many of these festivals may include acoustic/folk performances)
  • Sheer distance between cameras/recorders introduces delay, so sync is off a bit (also possibly caused by reflections in large, loud indoor venues)

I'll have a better picture of the problems I'll encounter once we get on the road. For now, I'm just brainstorming solutions so I don't have to worry, and because I can convince the team to spend a little grant money on infrastructure that will make our jobs easier. That being said, we're not rolling in cash; I doubt we'd be able to purchase more than 2 lower-end sync boxes, so your comment regarding rentals is highly valid and something I'll be looking into more.

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What cameras are being used?  That would highly tailor my advice.

 

Audio inputs - can be used to send audible timecode or a mono reference track.  Final Cut X actually does a pretty outstanding job of making multi-cam clips out of field recorder files along with camera clips, as long as a good common reference track is sent to all cameras.  Doesn't matter if clips start / stop, contiguous, what have you.

 

Timecode - many cameras don't have any timecode facilities at all, and some do, but cannot be jammed to an external device at all, effectively making it the same as no timecode at all for our intents and purposes.  The thing about timecode, is that it has nothing to do with synch, but simply stamps the metadata at the beginning of the recorded clip.  If there are long takes, cameras may drift, because timecode has nothing to do with keeping the camera "on time".  For most jobs, however, simple timecode is enough, and any NLE can drop in clips and spot them to the proper point on the timeline fairly painlessly.  If there needs to be a minor editorial nudging here or there to correct camera drift, no biggie (depending on how resilient your editor is in dealing with his natural OCD).

 

Genlock and tri-level synch.  Here is the professional way to approach it, albeit expensive.  Timecode is used to stamp the clips at the head, and genlock is used to force the video generator to synchronize with the house synch.  Studio cameras would be hardline to house synch where EPK units would use something like an Ambient lock-it equipped with Tri-level output (the modern ones can be in turn wirelessly synched up too, although I think that is overkill as any Ambient product I've ever used has run flawlessly on time for hours and hours).

 

Then there are the old fashioned ways of doing it.  You could put a master clock running TOD timecode somewhere visible that cameras could point to at the head and / or tail of each clip they shoot.  You could put multi-pattern tones in the PA that would give audio reference points that every mic in the house would pick up and record.  Same could be done with a high power strobe or flash (gives a nice little pop when a mic is right next to it).  Ultimately, if absolutely nothing was done at all except set cameras to more or less TOD free run, some poor AE could make it right, so determine if they want to pay for an AE to fix it or if that equivalent amount of money can go to renting the correct gear, and in no case can I see an iDevices solution being realistic for a typical production environment, either good idea that won't be able to be implemented as fully as it needs to, too high risk of failing in real world field conditions, or simply making the process too complicated when it could have been done in a simpler / low tech fashion.

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I had terrible luck with clocks etc that cameras were supposed to shoot.  A few film camerapeople back in the day were disciplined enough to shoot the big Denecke "concert" slates or the CRT monitors in the old Panavision concert system, but usually their average was a lot less than 50% of camera starts slated in my experience.  The long-lens guys blew it off right away.  Shooters today don't understand the TC display thing, and in outdoor concerts they never worked that well anyway.  I also have experienced the need for far more than minor editorial nudging re sync in situations where the TC is not regulated and consistent across all devices.  It all can be done, but eventually and with much detective work and time spent.  Is it ok to shove this much extra work downstream to editorial, in this case?   Multicam live-concert sync is expensive, and savings in production usually result in more expense in post just to get the footage to a cuttable condition.  

 

p

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What Phil said. ^

 

I see no good solution except to get Lockit/Denecke SBT boxes on every camera, jam them at the beginning of the day, then assume it'll be within a couple of frames of audio sync throughout the event. It'd help to have a scratch track on the cameras if possible. 

 

I have done at least five or six major concert projects on film where we wound up having to do a lot of eye matching and guesswork in post. Eventually, it all worked but it was very tricky in the bad old days. Famously, when Martin Scorsese and Thelma Schoonmaker edited Woodstock, it took them and a staff of six people like 4 months, working 7 days a week, just to sync up all the footage. And that was before they could start to edit it.

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What cameras are being used?  

We have one Sony PMW-300, one PMW-200, and another broadcast Sony slightly older/lower than that. The 300 and 200 will be the standard cameras to use. They both have TC and Sync input.

 

So to sum up what I've heard so far:

  • Get good reference audio if nothing else
  • Best solution would be TC/Sync boxes
  • Second best would be just TC with some added work in post

I haven't heard a definitive answer on why TC via Movieslate/WiFi absolutely won't work, but comments on potential unreliability and over-complication are noted.

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Re the wifi issue, the problem was that the range was too unreliable and unpredictable when used all around a big venue with lots of people, structures etc in the way, esp when cameras were roving and there were many other very strong WiFi transmissions in the air.  We can't expect that the shooters will contantly monitor the state of the TC reception or if the TC they are seeing makes sense for that moment, and they don't.   It has to be much more set-and-forget.  I myself am not very interested in solutions that work only part of the time, esp if I don't know which parts of the time that will be.

 

Re sync + TC vs TC by itself: it's important to remember that TC input to a camera does nothing at all about real sync to anything else, right?  All it is doing is labelling the frames, not controlling the speed at which the frames are being made by the camera.  Controlling that, and thus the real duration of shots, has to be done by controlling the sample clock of the camera.  If you don't do this, the sync of camera and sound recordings will drift.  You can end up with sync that is correct re a numerical TC address (ie they are the same on pix and sound) but NOT in sync, because the two recordings were made under different clocks at different speeds.  This is often not enough of an issue in shortish takes to worry about, but it can be a factor in long-roll concert shooting.  I usually want to eliminate as many variables re sync as the producers can afford to, thus I like TC boxes (and cameras) that allow for ext TC and TriLevel sync.  Meanwhile, all the other "partial" sync scenarios can work too (and I've used most of them at one time or another), they just cause more work to be done downstream, usually.  One producer I did a great deal of concert work for decided that it was ok that his sync was approximate across a very mongrel and changing assortment of operator-owned cameras on his funky shows because he always wanted to touch up the apparent sync of shots in post anyway (by moving pix relative to sound).  He was willing to put the time into that, so he got away with just doing locked down audio and simple "3,2,1 GO" camera TC sync.  

 

p

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I'd think that various delay issues caused by actual distance would make frame accuracy and genlock somewhat irrelevant.

I watch concert videos all the time. They cut between venues on the same song, requiring slipping sync and or/changing speed. The editors will deal with little changes.

Wifi would be wholly unreliable, but an SB3 or equivalent (very cheap to rent - your camera house might even throw them in) would do the trick. Camera house might even throw in Ambient boxes, if that's what they have, and you can genlock if you want to.

Get good sound and almost frame accurate TC, and they'll be just fine. Your biggest problem will be keeping the camera people from taking off or unplugging the boxes. They seem to do that. Or bad cables.

My 2 cents.

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I'd think that various delay issues caused by actual distance would make frame accuracy and genlock somewhat irrelevant.

I watch concert videos all the time. They cut between venues on the same song, requiring slipping sync and or/changing speed. The editors will deal with little changes.

Wifi would be wholly unreliable, but an SB3 or equivalent (very cheap to rent - your camera house might even throw them in) would do the trick. Camera house might even throw in Ambient boxes, if that's what they have, and you can genlock if you want to.

Get good sound and almost frame accurate TC, and they'll be just fine. Your biggest problem will be keeping the camera people from taking off or unplugging the boxes. They seem to do that. Or bad cables.

My 2 cents.

Frame accuracy and genlock are far from irrelevant in this context, as someone who has had to do the post sync on many of this sort of shoot I can assure you.  The closer to sync, and more importantly the more consistent you can make the sync, the better off everyone downstream is.  In any concert or event multicam shoot there is a certain level of chaos built-in, unforeseen issues that will need fixes in post.  There is no reason to add to these unnecessarily by using sloppy technique in production to the degree that good technique and technology can be afforded.   The OP may be "just fine" with inaccurate and inconsistent TC and camera audio, but the people downstream from him in post may not be so happy with this method.

 

In 40 years of concert shoots I have never had a camera operator remove the sync box or the TC/genlock cables from their camera, they are usually paying not attention to that kind of thing at all.  A concert shoot is a very different animal from a normal dramatic shoot.  The cables?  Things one checks out in the prep?

 

philp

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I had terrible luck with clocks etc that cameras were supposed to shoot.  A few film camerapeople back in the day were disciplined enough to shoot the big Denecke "concert" slates or the CRT monitors in the old Panavision concert system, but usually their average was a lot less than 50% of camera starts slated in my experience.  The long-lens guys blew it off right away.  Shooters today don't understand the TC display thing, and in outdoor concerts they never worked that well anyway.  I also have experienced the need for far more than minor editorial nudging re sync in situations where the TC is not regulated and consistent across all devices.  It all can be done, but eventually and with much detective work and time spent.  Is it ok to shove this much extra work downstream to editorial, in this case?   Multicam live-concert sync is expensive, and savings in production usually result in more expense in post just to get the footage to a cuttable condition.  

 

p

 

True story...  Back in the mid-1980's, Jeff Wexler was doing a concert shoot for a new up and coming rap / hip-hop group, Public Enemy.  Jeff and the boys were back stage smoking the ganj when some tussle broke out - something about touching someone or others girl, or maybe it was the girl that was touching Jeff, anyways, the camera guys jumped in to break it up and their tri-sync level boxes got broken while pulling Jeff away from his victims.  It was at that point Jeff had to help camera fix the synch issue and since he had just demonstrated his beastliness to the performers, they were in no position to argue with Jeff "pre-fade listen b*$ch" Wexler - using the only thing that he had at his disposal, the green room wall clock, he put a chain on it - and at that point, history was made...

 

post-1336-0-84812400-1431466207_thumb.jp

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Tom said: "True story...  Back in the mid-1980's, Jeff Wexler was doing a concert shoot for a new up and coming rap / hip-hop group, Public Enemy." Is this someone else named Jeff Wexler because it sure wasn't me in this "true story". What's the deal, Tom?

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True story... Back in the mid-1980's, Jeff Wexler was doing a concert shoot for a new up and coming rap / hip-hop group, Public Enemy. Jeff and the boys were back stage smoking the ganj when some tussle broke out - something about touching someone or others girl, or maybe it was the girl that was touching Jeff, anyways, the camera guys jumped in to break it up and their tri-sync level boxes got broken while pulling Jeff away from his victims. It was at that point Jeff had to help camera fix the synch issue and since he had just demonstrated his beastliness to the performers, they were in no position to argue with Jeff "pre-fade listen b*$ch" Wexler - using the only thing that he had at his disposal, the green room wall clock, he put a chain on it - and at that point, history was made...

attachicon.gifFlavor.Flav.jpg

Hahahaha. Great origin story Tom.

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