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Timecode Drift in Metacorder


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Hey there

Having a very weird issue that just came up in post on my show right now. Im running Metacorder on my macbook Pro and using OS 10.7.4. I know that Metacorder isn't necessarily supported to run in Lion but I've had no problems my past few shows with it. Im using a fire face 800 and an Apogee Big ben Word clock to clock the fire face and my DM1000. Running metacorder in monophonic mode with between 12 and 20 tracks per day (running 8-12 hours a day) to 2 G-tech Mini firewire drives (powered locally, not bus). Ingesting timecode either from a master clock from video when we shoot on our sound stage or from an Ambient Lock-It when we shoot in the field and I use my cart. So using different gear on my cart and at the stage too (the only constant is my macbook pro and my hard drives).

My problem is that no matter where we shoot or what we shoot, post has just informed me that my multi tracks are drifting and don't sync to cameras. Its not that my multi tracks are going longer than the cameras, but they are running faster so by then end of each of my wave files they are a few frames to over a minute (totally random, no pattern) faster than the cameras which are pretty close to sync with each other (Panasonic 900 cameras, 3-6 running 29.97 NDF which is what Im running). I usually break my files every hour to make it easier for post and when I do, the files are back in sync (which makes sense since metacorder time stamps the first frame of each file).

I've been using metacorder for years now and I've had a few hiccups in the past but nothing like this, and nothing that happened across every file I have been recording. Post is looking at me for an answer as they have to manually sync everything now (and they have no budget for this).

Any ideas out there? I know post is running Avid Media composer 5. I actually tried boom recorder 8 last shoot day since its made to run in Lion to see if that would make any difference. I know there is usually a little drift that occurs between cameras and metacorder but usually a few frames so no real syncing issues, but this has got me pulling my hair out.

Thanks in advance for any advice.

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I think the Mac OS has little or no bearing on the problem. Your setup is not relying on any clock within the OS. If Metacorder launches and runs properly with Lion, it is doubtful that Metacorder or your Mac are the source of the problem. If the tracks are consistently running long it must have something to do with how your files are being input into the Avid (or the manner in which they are being played out, possibly improperly being referenced to a different frame rate or TC rate).

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Are you using Fireface 800 interfaces in both setups? While the OS might not be the problem, not having the right driver for the interface/OS combination installed could be. How well did your Boom Recorder day stay in sync?

You mentioned that the Lion/Metacorder combo hadn't caused any trouble on previous shows which does point to editorial having some project setting or procedural problem with Media Composer 5.

Best regards,

Jim

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Wait--you are using a Big Ben to clock MC and your mixer, but taking TC from video? Are you clocking the Big Ben or whatever is clocking your MC rig to the incoming TC? If you aren't then there is a good chance you will have a sync issue re video.....the TC and the word clock have to be in sync with each other. Sorry if I didn't understand your rig correctly....

phil p

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Hey guys

Thanks for your feedback. Post assures me all there settings are correct, even though they won't go over them with me except to say that they are pulling in my MC data at 29.97 NDF. Last season there was a different sound supervisor on the show and he recorded everything with ProTools. They tell me they had no issues with those files and they haven't changed their settings. This job is a lot of run and gun between setups and I think a Protools rig would be a real pain in the field, and all I'm doing any way is recording time stamped broadcast wave files, so really can't account for why that would be any different. If there are any Avid settings anyone out there could send my way to send to post that would be appreciated as I really don't know Avid.

I am not sending video sync to the Big Ben but did consider that today since I am taking TC from the tech clock. If I do that, I would assume the cameras need to be genlocked to video sync as well to avoid a lot of other problems. Right now the cameras are just jam synced a few times a day to the master clock but don't have lock it boxes (but post assures me the cameras are in sync with each other).

No news on Boom Recorder yet as they only pulled the footage in today (they actually weren't even planning on testing the BR footage for another few weeks,,,,I argued that since I'm trying to fix the problem they need to give me some sort of feedback now, since we are partially through a new season of the show).

Thanks again. Any other suggestions would be welcomed.

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Im about to get a little long winded here. If you don't want to read it scroll down for what I think the problem is. I run a metacorder cart myself and am about 99% sure of my answer.

So first thing to mention, time code and clock source are two very different things independent of each other. The similarity between the two are that they both use a clock (does not need to be the same clock)

Lets start with timecode.

Timecode is little more than an arbitrary number that gets added to the meta data when you hit record. Syncing the camera and whatever devices does nothing more than to make this number the same across multiple devices. Time code drift should not do anything to the length or quality of a file.

Next is word clock.

A word clock is a device whose sole purpose is to control the frequency that a digital sample (or word) of audio is taken. at 48,000hz, this happens 48,000 times in 1 second. No clock is made exactly the same and all have some amount of jitter. (a slight difference in the amount of time from one sample to the next.) It is for this reason that when you try to connect two digital signals together (adat or whatever) you get clicks and pops. Those clicks and pops are the direct effect of jitter within 2 different clocks. Using a common word clock like a big ben runs the sample rate from one common device eliminating this process. A good quality word clock has very low amounts of jitter compared with a poor quality word clock. In all word clocks there will be some kind of drift. It is the length of the recording and quality of the clock itself that will dictate how bad your drift is.

With a poor quality clock, with an hour of straight recording, you will see about the amount of drift you have described.

Now on to your specific problem.

The big ben is a top notch / top of the line word clock. There is no reason for you to have any clocking issues at all with this device, so there are two possibilities here.

1. In the core audio driver (you see it come up when metacorder starts) there should be an option to chose which clock your device is running from. Just because the big ben is plugged in to your IO does not mean that is where the clock signal is coming from. This is an option you need to set. Next time you have the program open, open up the core audio settings. There will be an option called word clock. Select the input method you have used for your device. Im 99% sure this is your problem.

2. If your settings in core audio are correct my next guess would be that your clock is far superior to the clock in the camera you are using. this would be a job for a genloc device like ambient products have built in. an hour is a very long time to roll, and in this time you will notice the difference between a good clock and a bad clock.

as for the few frames of drift your files currently have, use something like the time shift adjustment in protools to adjust the few frames you are out. on an hour long recording, you will never notice any difference whatsoever.

Also edit to add that your computer, os, and anything else will not effect your clock. only the physical hardware IO will dictate clock quality. I switched to lion on my personal metacorder rig and have not had any issues with it whatsoever. It is an awesome program that is rock solid. I have been running metacorder for several years now as my main setup and have never had a single issue with it that wasn't some dumb user error.

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I agree with thesounguy's explanation of timecode and sync.

However, I suspect your problem is the Big Ben. It's a music grade clock, just like your FireFace and DM1000. By music grade I mean while it no doubt produces low jitter and perfectly formed clock signals, the oscillator was never designed to broadcast video specs of 1ppm or better drift. It could be anything from 10ppm to 1000ppm which means it might be fine for 10 or perhaps 20 minute takes and even then it might be a frame or more out of sync.

Apogee don't publish a ppm spec for the Big Ben but as an example of a music grade clock, Yamaha spec the DM1000 at 1000ppm. Not good.

Use the wordclock out of your Lockit to feed the wordclock input of the Big Ben. It's a 1ppm or better grade clock and can be tuned to 0.2ppm. The clock source on the Big Ben should be set to WC. Feed the TC to Metacorder.

On the stage, if you can get your video people to send you composite video from their sync pulse generator, you can use that as an external clock source for the BIg Ben. The Big Ben can't handle try-level sync.

I also wouldn't trust the cameras to be in sync over long periods despite what editorial tells you unless they have Lockits or Denecke Sync Boxes on them and are using both TC and Video Sync.

There's nothing like an old school clap stick at beginning and end of a long take to see who's in sync and who isn't.

David M

(Metacorder with a Metric Halo2882 interface. WC & TC from an Ambient reference tuned 744T = less than 0.04 frames drift in 10 hours against the best video sync available).

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I guess I'd want to know exactly what post means by "the cameras are in sync with each other". Do they mean dead frame for frame sync? One can cut together a scene from multiple cameras that aren't really synced to each other at all if you are willing to fiddle with the edits, which is done most of the time anyhow (ie DSLRs etc).. I think you may have to get much more into their business to find out what's going on, which will take some time and effort. As was said, just jamming TC on multiple devices is not really "syncing" them at all, it's just starting their counters at the same moment, after which they wander off on their own clocks. My take on your set up is that there are too many unreliable clocks working for long-term frame accurate sync to happen. The cameras should have lockits (unless they are Alexas) and you should have a similar master clock for your rig. I don't know if a Big Ben has the same level of accuracy of the clock in SD or Zax recorders, or Lockits. In any case you need something of that level accuracy to drive whatever audio interface you use for your computer. I'd start with making sure your own rig is really locked down, and then work on the cameras. I've had good luck post syncing unlocked camera footage to locked production sound files, a lot less luck the other way around.

phil p

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Hey guys

Thanks again for all your feedback. I have set my lockit box to send me bi-level sync into my big Ben. I had always assumed the big Ben was stable enough to handle the demands of my shows and didn't know that there was so much room for error when using it. I knew the dm1000 clock wasn't good enough to handle recording as I've had issues with it on previous shows. I will talk to my tech supervisor regarding your other camera suggestions. I only gt vague info from post about camera drift with each other and all they keep saying is that it's audio that the issue. Cameras are in sync according to them but they don't really give me a definition of what this means. All I get is on previous seasons of the show they didn't have drift issues. I'm also going to continue running boom recorder as I like the interface better and will hopefully hear back from post today regarding the first day I spent using it last weekend. I asked them to try syncing to one camera only instead of pulling my audio into a group of cameras to test at that level.

Please let me know if anyone thinks of anything else here. Been really frustrating, especially since I haven't come across this before. I know my takes are generally longer than when recording scripted shows but that's the nature of reality, and I would hope that these multitrack programs would record in sync no matter the length of the files.

-Danny M.

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Also. Just a side note to thesoudnguy's post. Thanks for all that info, but I was wondering what you meant by selecting "word clock" as your core audio device. Are you referring to the input device? If so, wouldn't I be selecting my fire face 800 which is synced to my word clock? Is there another option to select the word clock on top of this?

Thanks

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UPDATE:

Ran a full day with boom recorder 8 (18 tracks, 19 hours) and had no apparent drift. I also just used sync from the big Ben but have been sending word sync from my lockit all day today. I'm sold on boom recorder when running Lion.

Thanks again for all your help and comments

-Danny M

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Also. Just a side note to thesoudnguy's post. Thanks for all that info, but I was wondering what you meant by selecting "word clock" as your core audio device. Are you referring to the input device? If so, wouldn't I be selecting my fire face 800 which is synced to my word clock? Is there another option to select the word clock on top of this?

Thanks

It's not your input setting as your audio device. It is your wordclock setting inside your core audio device drivers.

os and program have nothing to do with the problem you had/have. It's a hardware problem.

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Some interesting clues here. I've never tried Word Clock as a source, but I have run Metacorder (similar to Boom Recorder) with an external Denecke GR-1, and it was rock steady. We had a few 10-minute scenes with zero sync issues. The Ambient Lockit is comparable and should work very much the same way.

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If you have the Lockit in your rig I don't see why you need the Big Ben at all. Can't you drive the mixer WC with WC directly off the Lockit (which you've jammed to the cameras and slates)? That would eliminate a whole variable, and the Lockits are very stable.

...and daisy chain the Fireface 400 WC input off the DM1000 WC out.

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On my fire face 800 settings I have had word clock set to external sync the whole time in its device settings. It sees word clock at 48k and is set to sync and lock so that was never the issue. Everything does work now though and the only change I have made is going from metacorder to boom recorder. Almost all of my takes are between 45 minutes to an hour and post said the drift issues didn't occur til about the 30 minute mark so I would suggest that if you're planning on long takes Boom Recorder is the way to go. Metacorder was functioning on shorter takes, but not on our show when I basically roll continuously all day long.

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Metacoder vs boom recorder was not the issue. No way, no how. The software will not make the recording drift. It is strictly a hardware issue, not software motivated whatsoever. Just because It is set to external sync does not mean you have properly selected where it is externally syncing from.

again, software will not affect how your hardware word clock works.

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Hey guys. For the test from post it was carried out on footage from Saturday before I fed my big Ben with word clock from my lock it box. The word clock was clocking my fireface from the big ben as the master And I know for a fact that I am getting the correct word sync to my input device from my big Ben. The only difference between metacorder no working and boom recorder working and syncing up is my software switch. I can't explain this other than metacorder is not supported to run in lion even though it does, and on all my takes it didn't start drifting until about the 30 minute mark. I am just telling everyone to be wary of this. I have used metacorder for many years now and have recorded thousands of hours in all sorts of environments but is is the first time I've had drift problems. Coincidentally it's the first time I've run it on os 10.7.

If anyone else can explain this any other way let me know. But I am definItely sold on boom recorder as my main recorder now.

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again, software differences would have no effect on how many samples of audio were taken within a file. It is driver/hardware driven. The same driver that runs metacorder is the same driver that runs BR - Core Audio.

It is in no way a software or os related. Also, where do you see that lion is not supported?

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Mark Gilbert said that he doesn't support running metacorder beyond os 10.6. Using the newest metacorder download (1.83 I believe). I have noticed that running metacorder vs running boom recorder is a lot more taxing on your CPU if you monitor your usage. Not sure if this has anything to do with it either. And as your takes increase in length, the CPU usage meter grows. Even when you have the flush the cache option enabled.

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Some interesting clues here. I've never tried Word Clock as a source, but I have run Metacorder (similar to Boom Recorder) with an external Denecke GR-1, and it was rock steady. We had a few 10-minute scenes with zero sync issues. The Ambient Lockit is comparable and should work very much the same way.

Hey friends,

Long time reader first time writer, I am currently building this exact set up with the exception of big ben, DM1000, to FF800 to Boom recorder or Metacorder, (been testing both, liking BR more) i was planning on using the Deneke GR-1 as the clock, my question to you, dspaceman, is are you using the timecode option on the Fireface 800? if so or not does any one know how that would work with the GR-1? could i use that as the "word clock" between all devices?

Any further information on this would be great as the rig is in the works.

thanks!

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