timecode for big multi-stage live broadcast (ambitious)

[lorenz]

Hi there!

I am looking for the best way to provide wordclock and timecode for audio and video for the following project:

We are planning a live broadcast of a 6 stage festival. We have a madi network that will give us a 56/64 channel feed from each stage into the broadcast console. (ie digico d5 console)

At any given time we will make mixes of two of the six stages with the broadcast console. One is the active broadcast mix, one the next act to be broadcast. we will use the rme madi bridge to choose which two stages out of the total six.

At each stage multiple cameras (up to 10 per stage) will be switched live for the big screens, this feed will be sent via sdi to the broadcast room.

Since the distances between stages and broadcast room are fairly large we use optical sdi and madi. We will send an sdi broadcast signal back to the big screens at all stages and other locations on the festival site. This will be used during the break when bands do their changeover.

Would it be possible to have a master clock in the broadcast room and use this last mentioned broadcast sdi signal to provide wordclock and timecode to the sound consoles as well as the cameras at each stage?

Or should we have a separate network for wc and tc? it's over 1000 meters between all the stages and the broadcast room.

How about redundancy? I really hate to think what happens if a connection fails or someone unplugs our master clock ;-)

[huub]

When we connect different trucks, usually one truck is the master (videoref), but for safety,important videosources go through a synchronizer, so if synch is lost, video remains stable..(frame synch takes 1 frame, so delay audio).. now for digital audio.. jeeez, running different stages *and* the broadcast from the same clock?? I personally would never want to do that.. AES sources can be reclocked by most big consoles.. Madi can't.. Or maybe it can..I'm not sure..
Anyone??

huub

[Jim vanBergen]

I'd get your broadcast tech manager involved. Make a SMPTE TC network hub with line amps and reader/regenerators and ADAs where they are needed. You want to use video black as the reference clock, not WC. Thats' simple using VDAs, again, make a hub and distribute.

How do you intend to seamlessly switch MADI on the DiGiCo, when it only takes three 56 pr boxes at a time? That's a cool trick, to swap from one MADI to another!

JvB

[fifthcircle]

Originally Posted by Jim vanBergen

How do you intend to seamlessly switch MADI on the DiGiCo, when it only takes three 56 pr boxes at a time? That's a cool trick, to swap from one MADI to another!

JvB

This is the RME box he mentioned: RME: MADI BRIDGE

I would think that if everything is clocked externally, you wouldn't have to deal with the clocking issues of resyncing when switching sources...

--Ben

[HughH]

Hello,
If it's really 1000 meters distance that you need to go, you shouldn't try to ship vid black or tc that far.
My suggestion would be to rent from Bexel a Telecast fiber system that has both analog video and audio, like the Viper, or the Cobra - they have several models that do just fine. Ship your analog video and TC to each stage, then convert to wc as needed. We've done this many times and it works well. Emmy's, Grammys, Oscars, and many more shows we've done have Telecast systems doing the sync distribution. I wouldn't suggest using them for critical analog audio paths - they sound ok, not great. Fine for average use and TC.
H

[lorenz]

Thanks for your replies!

Originally Posted by HughH

...rent from Bexel a Telecast fiber system that has both analog video and audio, like the Viper, or the Cobra ... then convert to wc as needed.
H

This sounds promising, now i'd like to know some more details. My background is audio, so I need some explanation with the video stuff...

1. can u name some devices that would sync to the signal sent to the stage but also continue to produce stable wc when sync is lost? If syncronised timecode could also be provided, everything would be perfect for the video guys.

2. instead of the telecast system (which might be difficult to come by where I am) couldn't I use the sdi signal to do the same thing that the Telecast system does?

btw, I am looking for the most cost-effective practical solution (otherwise i would probably simply get one evertz 5600MSC at each location and sync them via GPS)

Thanks again everybody!

Loz

[huub]

1: Rosendahl nanosyncs HD, produces wc even after losing videoref.. BUT not sure what will happen then, as the wc from the nanosyncs becomes different from the wc of your source (the other stage) then..

2: not sure what you mean, The telecast is basically an analog device (modulates the signal, then converts this modulated signal to fiber).
I'm sure there are digital devices that do this? The telecast is old technology, and, as stated before, sounds, well.. kind of crappy-ish..

huub

[lorenz]

Ha great, very quick reply!

Thanks, Huub. Interesting question about loosing sync... would it resync without nastiness... with audio it should work... does anybody know more about this?

what I mean with 2. is that we will have an optical sdi line going to all stages... (or can the telecast stuff be used to carry sdi? sorry i didn't look very closely at the specs) so I wonder if THAT could be used instead to extract wc etc...

Greetings,
Loz

[HughH]

Hello,
There's very little fiber gear that will carry wc unless it's audio-specific like RME.
Telecast makes modules that carry sdi as well.
The Rosendahl HD (not the old one) will gracefully resync to restored vid sync.
If you're shipping optical sdi around you can mux the tc in the sdi, then de-mux it on the other end to analog. You'll also have to convert sdi black to analog black for your video>wc converters, whatever flavor you are going to use.
Keep in mind I've suggested things that would "normally" be done in a large scale tv production. If you don't have that gear there are certainly workarounds. One example is if you demux your sdi to aes, you have a built-in sync source right there. The problem is if you lose sync then your recordings will stop. That's why a vid>wc converter is recommended.
H

[lorenz]

Thanks HughH,

...the nanosyncs look like the way to go on this project.

Originally Posted by HughH

Hello,
If you're shipping optical sdi around you can mux the tc in the sdi, then de-mux it on the other end to analog.

We have asked a company to provide analog-to-sdi-optical converters, but I don't know what kind of boxes they are.

Could you suggest some brands that could take analog video and wc (even tc) and turn it into an optical sdi muxed with tc like you mentioned above?

My understanding now:
we ship otical sdi muxed with hd/sd video sync to each stage where it will be demuxed and converted to coaxial sdi (and possibly analog video). the tc (hd/sd video sync) signal will be fed to nanosyncs at each location to provide reference for digital consoles and cameras. Right?

So, how do we mux sdi and hd/sd video sync? Which machine does this?


Regards,
Loz

[lorenz]

Hi again,

I have attached a diagram which shows my (lack of) understanding so far.

One thing that I am not very clear about is the video sync... do the video sync outputs of the nanosyncs include timecode? or is it just to sync the framerates etc.?

In the diagram i only drew 2 stages... and it all looks a bit crap. We would probably need two nanosyncs per stage if we have more then 6 cameras is that correct?

Nagging,
Loz

[huub]

time code is separate.. video sync makes sure every location shows every frame (well, line) of video at exactly the same time, audio sync ensures every sample is heard at the same time, timecode is a separate audio signal with hour/minute/second/frame information..

[HughH]

Hello,
You really need to pay for the services of a local video engineer on this one - your questions indicate you need one. It's nearly impossible to specify a complete multi-camera video system infrastructure build via a forum. That said, I'll attempt to clarify a little.

If you're doing a shoot with multiple sync'd cameras then the Nanosyncs would not be your video sync source - the camera system will have a master sync generator and da's to distribute to your cameras and any local record decks. From this video black da you'll feed the Nanosyncs to derive wc for your local audio devices. The multiple video black outputs on the Nanosyncs are a convenience for an audio setup, but the video folks won't use them. They'll use a master sync source like a Tektronix Master Sync Generator or similar.
The video master sync generator for each stage should be fed black from the main video black of the broadcast room. If this signal goes away then the local Master generator takes over so the cameras can keep going.

LTC (linear time code) is inherently an analog audio signal even though it has bits. Distribute it however you need to - fiber, embedded, whatever - from the broadcast room to the stages.

H

[lorenz]

Hi HughH,

thanks for your patience and for trying anyway to shed light into the darkness

Ok, I recap:

local master sync source such as the tektronix to sort out cameras and nanosyncs (nanonsyncs might not even be necessary cause D5 has video sync input, but certainly convenient)

local master syncs get video black from broadcast room via a fiber cable product that can carry sdi and video black such as the telecast viper.

The LTC isn't really a big issue and I think it's probably enough if each stage use their own timecode for the local cameras.

Well, one thing I am trying to establish is how many fiber lines we need to put in the ground. I am hoping that 2 fiber lines from and to every stage will be enough.

Of course we have video engineers - a whole team, but they r Chinese with bad English and, for me at least, even in english it seems rather complex.

Since I am responsible for the audio network and broadcast I want to understand better the video people's needs. I wanna understand how video setups work in principle so we can make sure all keeps working during the event... so I'd like to know the key components for video and example models. Call it a personal quest for better understanding.

You all have been very helpful already and actually I have a much better picture of te setup now.

best,
Loz

[Jim vanBergen]

All good stuff so far!! (and I like the MADI interface you're using!)

Just another quick opinion:

If each stage has its own truck or broadcast suite with their own ENG department, tape ops, etc sending a line cut to master control, then they can each run on their own TC, usually TOD military (24 hour clock SMPTE, 29.97df).

If you have ONE master control (which I suspect, as each stage is running to your master audio mix position) then each stage should be run from master controls' Video Black and TC master. If you run TC down fiber that's fine, ultimately you are still making a TC hub and providing star distribution for code to each location. I'd still make sure each stage has a reader/regenerator in case of a timecode dropout in the fiber somewhere.

The standard for Adder/Viper when I have used it (about fifty times in the last ten years) is two optic runs (main system & backup systems, with a backup head).

I have done large events like this where the tech manager provided fiber and that's great, but I always demand a copper backup be available (hopefully run & in place)- I have ended up using copper in several instances, even over a mile with audio and video amplification to make the levels work, on live broadcasts for sports, concerts, parades, etc. Better safe than sorry. If a copper backup is simply not possible, run additional fiber lines. We're putting in a huge system right now that is all running DiGiCo with MADI, and we ran three sets of spares for each stage rack. You can't be too careful, and cable is cheap compared to failure on a live broadcast. That's why most events have TWO satellite transmission trucks and TWO birds.

Hope this helps!

JvB

Originally Posted by lorenz

The LTC isn't really a big issue and I think it's probably enough if each stage use their own timecode for the local cameras.

Well, one thing I am trying to establish is how many fiber lines we need to put in the ground. I am hoping that 2 fiber lines from and to every stage will be enough.

[lorenz]

Hi Jim,

Originally Posted by Jim vanBergen

If you have ONE master control (which I suspect, as each stage is running to your master audio mix position) then each stage should be run from master controls' Video Black and TC master.

...You can't be too careful, and cable is cheap compared to failure on a live broadcast. That's why most events have TWO satellite transmission trucks and TWO birds.
JvB

You are right, it would be great if timecode could also be run from a central location but I think the hassle introduced by doing so possibly outweighs the benefit of having two stages run exactly the same time code, as long as all stages use the same wc/sync and can safely loose sync and resync. And, yes, each stage has their own video suite.

The production room will only get the big screen cut of each stage. We were considering to remotely control editing at each stage by sending the lower-quality preview versions of each stage's 10 camera signals via fiber to the control room and do the switching via remote control from there... but we decided not to try too much this time (and i thought it is not even a very great idea anyway)

As far as the technical setup is concerned the event is a bit of a showcase of the organiser's abilities, however the broadcast is not 'mission critical' therefore we don't run full redundancy. But of course you are right if it was there would be no question about doubling up whereever possible.

Onother reason why i don't want copper cables (which are more expensive than fiber) is because some stages use their own generators and the production room is on grid power... I have had serious line potential issues in previous years and going optical is a great way to solve these issues (basically i'm scared to get electrocuted!)

Greetings,
Loz