Video/Audio Sync?

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01-06-2008, 03:14 PM
gazzer82

Video/Audio Sync?

Hello All

I have a show coming up that has a lot of video clips with audio, vox pops and interviews and such like. Some of the clips are quite long and i am worried about sync issues if i playback the audio and video from Catalyst, i have had problems in the past where they drift after a period of time.

So i am looking for suggestions as to a way to address this, either within catalyst or by using an external device for the audio playback. There will probably be a Q-Lab or SFX system used for other audio playback so the audio could be played back from those systems instead. But again we would still need to ensure that they stay in sync.

I had though of using MTC, but as this will be a cued show there will be no timeline to take the MTC from so i don't see how this could work. I guess i could create a separate cue list in Catalyst and set it to use the incoming MTC as it's clock source. But i still have to get that source from somewhere.

Would striping the audio to some kind of hard-disk playback unit that outputs the MTC and then triggering that from another cue list work?

Any help greatly appreciated!!

Cheers

Garet
02-06-2008, 06:51 PM
Improve

Quote:

Originally Posted by gazzer82

Hello All

I have a show coming up that has a lot of video clips with audio, vox pops and interviews and such like. Some of the clips are quite long and i am worried about sync issues if i playback the audio and video from Catalyst, i have had problems in the past where they drift after a period of time.

So i am looking for suggestions as to a way to address this, either within catalyst or by using an external device for the audio playback. There will probably be a Q-Lab or SFX system used for other audio playback so the audio could be played back from those systems instead. But again we would still need to ensure that they stay in sync.

I had though of using MTC, but as this will be a cued show there will be no timeline to take the MTC from so i don't see how this could work. I guess i could create a separate cue list in Catalyst and set it to use the incoming MTC as it's clock source. But i still have to get that source from somewhere.

Would striping the audio to some kind of hard-disk playback unit that outputs the MTC and then triggering that from another cue list work?

Any help greatly appreciated!!

Cheers

Garet

Don't see the big problem... playing back audio from any playback device and syncing the catalyst videolayer to MTC has worked for me before... With the in/outframe you can assign your MTC offset if needed...

So playback audio, playback video but with playmode => sync to MTC No need for timeline for the rest of the show :)
02-06-2008, 10:38 PM
Woodj32177

So, just for my curiousity,
How do you reference the video to the timcode?
I understand how you get the video into the catalyst, but where does the video get timecode? is it a part of how you encode it?
Joshua Wood
04-06-2008, 08:17 AM
SourceChild

Quote:

Originally Posted by Woodj32177

So, just for my curiousity,
How do you reference the video to the timcode?
I understand how you get the video into the catalyst, but where does the video get timecode? is it a part of how you encode it?
Joshua Wood

Every video clip has timecode associated with it. The same goes for every audio file.

You can reference from another machine playing an audio or video that outputs MTC (usually SMPTE). In Catalyst, you just plug in the SMPTE into the microphone input on your Mac or MTC into the MIDI port on your CIB (if you have one) or another MIDI interface. Then set it up in the Catalyst control.
04-06-2008, 07:55 PM
gazzer82

Aha, i hadn't noticed the sync to mtc playmode before you mentioned it. So odd that you can spend so long looking at an interface and never actually clock what's there.

Just need to persuade the venue to purchase the show control sfx license now so that i can actually get MTC from them to reference too.

Though in fairness i have done a lot of testing over the last few days and i haven't yet managed to get the audio/video to slip out of sync. So potentially this may not be required.

Thanks for the help!!

Cheers

Gareth
04-06-2008, 08:25 PM
Peter

Quote:

Originally Posted by gazzer82

Just need to persuade the venue to purchase the show control sfx license now so that i can actually get MTC from them to reference too.

We use Qlab instead of sfx but we started with sfx which by the way is for sale (educational version). If your interested please let us know?

QLab and motu are rocksolid on mac.
04-06-2008, 09:14 PM
SourceChild

Uh...

Just a suggestion guys but sometimes I will setup an extra Catalyst Machine as an Audio server and sync to it.
05-06-2008, 12:10 PM
samsc

Quote:

Originally Posted by gazzer82

Though in fairness i have done a lot of testing over the last few days and i haven't yet managed to get the audio/video to slip out of sync. So potentially this may not be required.
Gareth

thats because - it doesnt 'slip' if the audio and video are in the same movie.
quicktime keeps them together-

--

if the audio and video are on separate layers - then thats different...and depends completely on whether your hardware can playback those layers without dropping frames-
typically with sata discs arent good enough- to keep long term stability-
if you get a machine with an SSD then you reduce the chance of dropping frames by many times-
If you are doing audio and video - i would very very strongly recommend the use of SSD's - to minimise any dropped frames caused by rotational latencies.

---

in the most recent versions of catalyst- there is a smpte reader for the audio input - so midi timecode isnt required.
05-06-2008, 12:11 PM
samsc

Quote:

Originally Posted by SourceChild

Uh...

Just a suggestion guys but sometimes I will setup an extra Catalyst Machine as an Audio server and sync to it.

this is done in a lot of shows-

as professional audio gear does what it says on the tin-

using a mac to playback audio from the sound output - is buyer beware.
05-06-2008, 12:13 PM
samsc

Quote:

Originally Posted by gazzer82

Aha, i hadn't noticed the sync to mtc playmode before you mentioned it. So odd that you can spend so long looking at an interface and never actually clock what's there.

Just need to persuade the venue to purchase the show control sfx license now so that i can actually get MTC from them to reference too.
Gareth

you dont need MTC - you can input timecode directly into the audio port and sync a layer to the incoming timecode directly-
You can also set time offsets for the inframe for catalyst layers.

just been used on sinatra tour.
05-06-2008, 12:34 PM
SourceChild

Quote:

Originally Posted by samsc

using a mac to playback audio from the sound output - is buyer beware.

I am curious at your feedback. I've got three different venues that have been playing Audio off their Catalyst machines for years. Easily over 5000 separate instances of playback with audio and I've never heard of problems. (Granted I had a few bugs with V3.3 and older on the old G5 machines.)

Now I have done things in different cases. Sometimes it was literally the 1/8" mini phone jack connected to a stereo DI. Other times an external USB or Firewire Audio device. Most times using SDI audio.

Where have you seen problems occur most.
05-06-2008, 01:45 PM
samsc

Quote:

Originally Posted by SourceChild

I am curious at your feedback. I've got three different venues that have been playing Audio off their Catalyst machines for years. Easily over 5000 separate instances of playback with audio and I've never heard of problems. (Granted I had a few bugs with V3.3 and older on the old G5 machines.)

Now I have done things in different cases. Sometimes it was literally the 1/8" mini phone jack connected to a stereo DI. Other times an external USB or Firewire Audio device. Most times using SDI audio.

Where have you seen problems occur most.

it works - its used a lot -

but because using audio playmodes - as i have said before - apple makes the movies prioritise audio - not video- so when you do this the video sometimes does not playback as smoothly as without audio. if the computer is doing too much - apple skips video frames.
this is a bigger problem with systems with only sata discs - and people using lots of layers at the same time.
hunting around for audio as well as video - and they are often on different parts of the discs - within the same movies- makes the rotational latency issues more critical.
05-06-2008, 01:49 PM
samsc

Quote:

Originally Posted by SourceChild

I am curious at your feedback. I've got three different venues that have been playing Audio off their Catalyst machines for years. Easily over 5000 separate instances of playback with audio and I've never heard of problems. (Granted I had a few bugs with V3.3 and older on the old G5 machines.)

Now I have done things in different cases. Sometimes it was literally the 1/8" mini phone jack connected to a stereo DI. Other times an external USB or Firewire Audio device. Most times using SDI audio.

Where have you seen problems occur most.

a more general point-
multitasking general purpose computer systems do not prioritise the allocation of any specific system resources to a single task.

a standalone audio playback unit - because it will be designed with only one function - and system resources prioritised to that single function - will likely be more stable. though not always.

---

In the design of general computer systems - it does not matter if a program crashes - or the OS goes and does something else for a few seconds-
In audio visual applications running on general purpose computers - ths behaviour is not appropriate - and there is no means of controlling these things in the operating system.

We have been lucky that it mostly works - almost all the time. and testing on shows over many years has shown adequate performance under long and continuous use. but this is still not exactly how these things are designed.
05-06-2008, 02:46 PM
SourceChild

Actually Richard,

You're exactly right. I wasn't sure though if you had additional considerations I haven't considered.

I guess it's a good thing to point out that I run scripts after each big event that set the state of the computer back to the "out of the box optimized' state. I tend to take for granted that the majority of people don't Re-Image often.

On a thought though... I've tried in the past to play audio files in PLAudio mode on Catalyst. Is there a way to integrate an audio only play mode so Catalyst can play audio as well as video files? ...and is there a way to input/output the timecode of it?
05-06-2008, 08:01 PM
Peter

Quote:

Originally Posted by SourceChild

I guess it's a good thing to point out that I run scripts after each big event that set the state of the computer back to the "out of the box optimized' state. I tend to take for granted that the majority of people don't Re-Image often.

Could you explain a bit more on "out of the box optimized"? And do you want the share the scripts or i can try to write my own if i understand this a bit better.
18-06-2008, 10:08 PM
SourceChild
Quote:

Originally Posted by Peter

Could you explain a bit more on "out of the box optimized"? And do you want the share the scripts or i can try to write my own if i understand this a bit better.

Sorry it's taken me a while to respond, I've been busy.

One thing very important to a Catalyst server is the ability to run without unforeseen issues. Ideally, the best way to make a Catalyst machine is to do the following:
- Use a MacPro not a G5 (preferable a 2nd Generation Intel)
- Buy a new SATA disk (this becomes your installation source)
- Wipe and "Zero" your system hard disk using the Installation Disk Utility
- Install your Capture Card (LFG4 or Decklink or the new Phoenix once released)
- Install your Mtron SSD disk (I suggest 2 64Gb disks in a stripe)
- Assure you have at least (my recommendation) 8Gb of Memory
- Make sure you have an x1900 Video Card (or Geforce 8800 or Quatro FX xx00)
- Clean your fans and heat syncs and connectors
The new disk I talked about becomes your installer disk. First, go to x86 project and lookup instructions for creating a bootable installation disk out of your spare SATA disk. (I say x86 Project because I am a hacker and their forums explain this the best. Granted you won't be creating a "Hackintosh").

One you have the Catalyst machine ready to go and your new disk formated GUID with the proper EFI, copy all the following to your new disk.

(Make sure you have an installation CD for Leopard)
- Leopard Full install DVD
- 10.5.3 Leopard Update Package
- Drivers for your Video card (not the newest, the ones we've posted here that "work")
- Drivers for your video card (ONLY IF APLICABLE and "drivers" only, not software)
- Drivers for your USB card (some of us do the HES thing where we put our dongle inside on a PCI USB card)
- The drivers for the Aladdin USB Software Key
- The newest version of Catalyst (currently m165)
- Read-Only Folder with whatever you decide to be your "Stock Content"
- System initialization scripts which include:
- --Applescripts to wipe the System disk and write Zeros
- --Applescripts to wipe the Mtron disks and write Zeros 3 times
- --Applescripts to build an Mtron disk Stripe Set
- --UNXI Shell-scripts to automate install
- --Applescripts to update to 10.5.3
- --Applescripts to install drivers for video capture
- --Applescripts to install drivers for video card
- --Applescripts to install drivers for PCI USB
- --Applescripts to optimize Quicktime
- --UNIX Shell-scripts to remove Time Machine
- --UNIX Shell-scripts to disable ExposÃ©
- --UNIX Shell-scripts to disable Dashboard
- --UNIX Shell-scripts to halt .mac services
- --Applescripts to create a Catalyst folder system
- --Applescripts to copy Stock Content to the Mtron Disks
- --Applescripts to install Catalyst into directories based on show type
- --Applescripts to install dongle drivers
- --Applescripts to disable Screen Saver and Energy Saver
- --Applescripts to install your different versions of Catalyst into the Dock

Loosely, this is how I do it. I wrote all these scripts based on research I conducted into how to do them. All of the scripts are separate and independent of one another so as to prevent errors. I have a global scripts that executes all of the aforementioned scripts in a progressive order.

Basically, when I get a Catalyst back from a rental where someone other than me has used it, I stick in the Installation Hard Disk and run the first script. Then about 4 hours later, I walk back and have a clean machine.

If anyone is interested in these scripts, I will make them available for sale once I have tested them thoroughly to make sure they are solid. I will offer them at a nominal price and shortly I will be releasing a full application that does all of these tasks. The application will not be ready until mid fall but the Script package will be ready by end of summer.