Audio drift using the Red in FCP

Robert Krupka · July 17th, 2008, 11:56 AM

I have a problem here that's kinda freaking people out.

I'm uncertain if this is a build 16 issue, but I'm finding that the audio drifts by as much as 2 seconds in longer takes. This is from syncing using the slate sticks only, not timecode.

I am observing this in FCP after using compressor to make Prores files out of the Redcode. Audio is being recorded at 48khz and 24-bit and the Red is shooting 23.98fps. The sequence settings in FCP reflect this. At times, we're recording sound straight into camera and this audio does not drift and appears fine.

If I'm leaving out important information to help solve this, please let me know. I'm no longer using compressor to make the prores files since the last firmware update broke that for me. I'll have to see if the problem persists with Redrushes.

Any thoughts on this? People are spooked.

Noah Kadner · July 17th, 2008, 05:06 PM

What are you using to record sound and does it have timecode?

Noah

Robert Krupka · July 17th, 2008, 06:51 PM

The sound guy is using one of those flash/hard drive recorders. I'll ask him what exactly when he gets back to set. It has timecode, but we're not jamming it to camera because there have been reported issues with it being out of sync, thus we used sticks only.

I found something out recently, however, that makes me think it's a FCP issue. I brought the footage into After Effects, synced the clap, and it looks fine. No drifting or anything wrong. What's going on here?

Steve Oakley · July 18th, 2008, 11:34 AM

are you sure the footage isn't 24.000 instead of 23.976 ? not sure if the FPS is embedded into the original r3d files, but if it is, I'd check there first and not assume anything.

and how long are the takes ?

last, what audio recorder ? the cheap ones can easily drift as you are seeing.

Robert Krupka · July 18th, 2008, 03:52 PM

The audio recorder definitely isn't a cheap one, that's for sure. But isn't it odd that it works fine in AE and not FCP?

The DP said he's shooting 23.98 .

The takes can be 3 minutes long. It really doesn't take long to begin to see the drift.

Meryem Ersoz · July 18th, 2008, 07:05 PM

you should still jam-synch, if you can. most of the audio drift that has been reported has been consistently 2 frames off, and it's a pretty simple procedure to adjust if you have consistency...

...that doesn't quite sound like the problem you are encountering, however.

it would definitely help to know more about the set-up.

other questions: how are you outputting sound? have you tried pulling in the proxies and rendering it straight out of the FCP timeline that you intend to use? or are you using compressor? or are you just pulling in files from the flash recorder and manually synching? are you recording double system, and can you get sound from both sources to align with each other?

Robert Krupka · July 20th, 2008, 06:58 PM

Thank-you for your help. We're shooting in a foreign country where the internet is scarce.

"how are you outputting sound?"

Through my MBP speakers.

"have you tried pulling in the proxies and rendering it straight out of the FCP timeline that you intend to use? or are you using compressor?"

Started with using compressor to make the prores files, but halfway through production the DP decided to update the firmware and now (even after updating my QT codec, etc) compressor outputs a garbled picture. I've been using Redrushes since then, but the drift still exists.

"are you recording double system, and can you get sound from both sources to align with each other?"

Yes, we're recording double system. In addition, sometimes the mixer will go into camera as a backup. In those instances, I can usually get the two sources to line up, but sometimes the in-camera audio is off by less than a frame.

Noah Kadner · July 20th, 2008, 07:48 PM

You definitely must jam sync the RED to your flash recorder- if you expect things to line up in post. I'd also go ahead and record into the camera too so at least you have something you know is being recorded at the same timecode and rate.

Noah

Meryem Ersoz · July 20th, 2008, 10:34 PM

Quote:

Originally Posted by Robert Krupka

I've been using Redrushes since then, but the drift still exists.

i still don't understand how you're outputting sound (by outputting sound, i didn't mean your speaker system, i meant how are you pulling sound files from the R3D files). you can pretty much render your sound out of the FCP timeline or Compressor, if your mixer or flash device is input into the camera at the line level. or you can pull audio files from your flash device into the timeline. if you're recording line level, double system...are all of your files drifting equally from both the in-camera system and the flash recorder?

Robert Krupka · July 21st, 2008, 01:00 PM

We're transfering the sound as files at the end of the day straight from the sound recorder (which is a Sound Devices 744T 4-channel recorder). The in camera sound stuck with the picture when I converted to prores through Compressor (Redrushes doesn't keep the sound, unfortunately). The in-camera audio actually isn't drifting.

Meryem Ersoz · July 21st, 2008, 01:14 PM

ok, now i get it. this is a known issue with the SD 744T. let me see if i can track down some data for you on how others have handled it. if you shoot me an e-mail, i'll send you some useful links describing it.

Jim Boda · July 21st, 2008, 07:22 PM

Quote:

Originally Posted by Robert Krupka

I have a problem here that's kinda freaking people out....

... Audio is being recorded at 48khz and 24-bit and the Red is shooting 23.98fps. The sequence settings in FCP reflect this. ...

Any thoughts on this? People are spooked.

Well, you can do a test recording at the 48.048 kHz sample rate to see if that syncs up better.

And make sure that TC is NOT set to DROP FRAME.

http://www.sounddevices.com/notes/re...sr-frame-rate/

Robert Krupka · July 22nd, 2008, 04:01 PM

I sent you my e-mail, Meryem.

July 17th, 2008, 11:56 AM	#1
Robert Krupka Regular Crew Join Date: Apr 2006 Location: New York Posts: 26	Audio drift using the Red in FCP I have a problem here that's kinda freaking people out. I'm uncertain if this is a build 16 issue, but I'm finding that the audio drifts by as much as 2 seconds in longer takes. This is from syncing using the slate sticks only, not timecode. I am observing this in FCP after using compressor to make Prores files out of the Redcode. Audio is being recorded at 48khz and 24-bit and the Red is shooting 23.98fps. The sequence settings in FCP reflect this. At times, we're recording sound straight into camera and this audio does not drift and appears fine. If I'm leaving out important information to help solve this, please let me know. I'm no longer using compressor to make the prores files since the last firmware update broke that for me. I'll have to see if the problem persists with Redrushes. Any thoughts on this? People are spooked.

July 17th, 2008, 05:06 PM	#2
Noah Kadner Better than Halle Berry Join Date: Feb 2004 Location: Los Angeles, CA Posts: 194	What are you using to record sound and does it have timecode? Noah __________________ Visit http://www.callboxlive.com/store/storemain.php for Final Cut Studio training DVDs from Noah! My RED Blog- http://twenty398.com

July 20th, 2008, 07:48 PM	#8
Noah Kadner Better than Halle Berry Join Date: Feb 2004 Location: Los Angeles, CA Posts: 194	You definitely must jam sync the RED to your flash recorder- if you expect things to line up in post. I'd also go ahead and record into the camera too so at least you have something you know is being recorded at the same timecode and rate. Noah __________________ Visit http://www.callboxlive.com/store/storemain.php for Final Cut Studio training DVDs from Noah! My RED Blog- http://twenty398.com

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July 17th, 2008, 06:51 PM	#3
Robert Krupka Regular Crew Join Date: Apr 2006 Location: New York Posts: 26	The sound guy is using one of those flash/hard drive recorders. I'll ask him what exactly when he gets back to set. It has timecode, but we're not jamming it to camera because there have been reported issues with it being out of sync, thus we used sticks only. I found something out recently, however, that makes me think it's a FCP issue. I brought the footage into After Effects, synced the clap, and it looks fine. No drifting or anything wrong. What's going on here?

July 18th, 2008, 11:34 AM	#4
Steve Oakley Major Player Join Date: Apr 2006 Location: United States Posts: 720	are you sure the footage isn't 24.000 instead of 23.976 ? not sure if the FPS is embedded into the original r3d files, but if it is, I'd check there first and not assume anything. and how long are the takes ? last, what audio recorder ? the cheap ones can easily drift as you are seeing.

July 18th, 2008, 03:52 PM	#5
Robert Krupka Regular Crew Join Date: Apr 2006 Location: New York Posts: 26	The audio recorder definitely isn't a cheap one, that's for sure. But isn't it odd that it works fine in AE and not FCP? The DP said he's shooting 23.98 . The takes can be 3 minutes long. It really doesn't take long to begin to see the drift.

July 18th, 2008, 07:05 PM	#6
Meryem Ersoz Wrangler Join Date: Jan 2005 Location: Boulder, CO Posts: 2,482	you should still jam-synch, if you can. most of the audio drift that has been reported has been consistently 2 frames off, and it's a pretty simple procedure to adjust if you have consistency... ...that doesn't quite sound like the problem you are encountering, however. it would definitely help to know more about the set-up. other questions: how are you outputting sound? have you tried pulling in the proxies and rendering it straight out of the FCP timeline that you intend to use? or are you using compressor? or are you just pulling in files from the flash recorder and manually synching? are you recording double system, and can you get sound from both sources to align with each other?

July 20th, 2008, 06:58 PM	#7
Robert Krupka Regular Crew Join Date: Apr 2006 Location: New York Posts: 26	Thank-you for your help. We're shooting in a foreign country where the internet is scarce. "how are you outputting sound?" Through my MBP speakers. "have you tried pulling in the proxies and rendering it straight out of the FCP timeline that you intend to use? or are you using compressor?" Started with using compressor to make the prores files, but halfway through production the DP decided to update the firmware and now (even after updating my QT codec, etc) compressor outputs a garbled picture. I've been using Redrushes since then, but the drift still exists. "are you recording double system, and can you get sound from both sources to align with each other?" Yes, we're recording double system. In addition, sometimes the mixer will go into camera as a backup. In those instances, I can usually get the two sources to line up, but sometimes the in-camera audio is off by less than a frame.

July 21st, 2008, 01:00 PM	#10
Robert Krupka Regular Crew Join Date: Apr 2006 Location: New York Posts: 26	We're transfering the sound as files at the end of the day straight from the sound recorder (which is a Sound Devices 744T 4-channel recorder). The in camera sound stuck with the picture when I converted to prores through Compressor (Redrushes doesn't keep the sound, unfortunately). The in-camera audio actually isn't drifting.

July 21st, 2008, 01:14 PM	#11
Meryem Ersoz Wrangler Join Date: Jan 2005 Location: Boulder, CO Posts: 2,482	ok, now i get it. this is a known issue with the SD 744T. let me see if i can track down some data for you on how others have handled it. if you shoot me an e-mail, i'll send you some useful links describing it.

July 22nd, 2008, 04:01 PM	#13
Robert Krupka Regular Crew Join Date: Apr 2006 Location: New York Posts: 26	I sent you my e-mail, Meryem.