Auido Drift Zoom & DSLR

[Ana Conlon]

I'm experiencing a big audio drift with footage about 45min long. I'm using 2 canon DSLRs and 2 zoom H1 recorders. It's really weird because I've used this method before with no issue. I'm syncing the audio using Pluraleyes and FCP. The footage was recorded at 25 frames.

the drift is big is massive the auido start to echo at 30 sec and its way off by 2 min's in. It very strange as I haven't experienced this before and I've used this method for years??. I create my prores files with MPEG stream Clip. And I pull my mp3 from my Zoom's and convert them to .aiff files using a switch (a free auido converter)

The 2 canons are syncing up no problem and the 2 zoom's but not everything together?

[Ty Ford]

Ana,

Thanks for reporting this. I keep telling people it happens and some refuse to believe me.

Did your previous successes have long clips too?

Interesting that the recorders are in sync and the cameras are in sync.

Regards,

Ty Ford

[Rick Reineke]

Interesting that the recorders are in sync and the cameras are in sync.
> Indeed..
PS- What's the sense (or lack thereof), recording to the inferior data compressed MP3 format.. then converting to PCM? It won't make the quality better.

[Ana Conlon]

Right well it’s getting weirder....!

In an effort to isolate the problem, I've gone back to a previous project from last week where everything synced as normal with no problems.

I have all the same files I used last week and when sync and these same files its now not working. Again it’s all way off! This is really strange because these same files worked perfectly a week ago. So now I can only assume it’s an issue with Pluraleyes or FCP.

I then aligned my audio and footage by eye. The audio is a perfect fit at the start and then again very quickly starts to echo and goes way off. So now I can only assume something has gone screwy with FCP. I'm very confused now????

I'm going to try an auld restart see does that improve anything! LOST

PS I record in mp3 because the quality is sufficient and the file size is small but I have to convert to aiff to work in FCP

[Richard Crowley]

I would recomend AGAINST using a compressed codec (like MP3). The risk of conversion artifacts is significant enough all by itself. But then when you are having sync problems also, it is another REALLY REALLY GOOD REASON to NOT use MP3.

Unless "file size is small" is more important to you than sync???

[Ana Conlon]

I've been at this problem all day and as it turns out it has nothing to do with the file formats or conversion. Its a new problem that developed within my FCP in relation to the sequence settings. I've done lots of digging around and experimenting today and I fixed this with the tutorial I found below. I'm still not sure how the problem suddenly appeared but the following work around has everything back in running order.

Fixing Assets in FCP using XML : Apple Final Cut Pro Tutorial

it may help save someone time. The tutorial is old and for much older versions of FCP but I think the main thing is making sure you create a new default sequence with all the correct settings you need for your particular project and exporting that XML file.

[Marco Leavitt]

Interesting. I regularly sync hours and hours of footage and have no problems at all.

[Richard Crowley]

Originally Posted by Marco Leavitt

Interesting. I regularly sync hours and hours of footage and have no problems at all.

Yes, it is the "luck of the draw". Some people are fortunate enough to have camera(s) and recorder(s) that keep excellent sync (or very good sync).for 5 or 10 or even 30 or 60 minutes at a stretch. But unless you are using equipment capable of syncing with genlock, it wouldn't be logical to DEPEND on such transient luck.

And, of course, some material doesn't demand millisecond sync accuracy, and some audiences don't perceive or care about exact sync, either.

[Paul Mailath]

Originally Posted by Ty Ford

Ana,

Thanks for reporting this. I keep telling people it happens and some refuse to believe me.

Ty Ford

I've had problems with long speeches and ran a test
http://www.dvinfo.net/forum/wedding-...dio-drift.html

no doubt in my mind that different recorders won't match over time

[Gary Nattrass]

You are bound to get drift on most sep systems as their timing clocks are not running in true sync.

The only way to do this is to drive one clock from another so they both have the same reference but as most domestic kit will not allow you to do this you will be stuck with the drift and it is best to run for short periods and to make sure that establish a sync mark at the head of each shot.

You may be lucky that two devices are closer than others but it is purely luck and it is like having two identical cars and running them down a hill. it will be highly unlikely that both cars will reach the bottom at the same time.

Systems are more accurate these days but the only way to get true sync would be to jam the clocks together as mentioned or to record a common sync reference such as timecode that can be used later to ensure that each source is transferred to the edit with reference to this common sync source ensuring that both systems are running to true sync speed.

DSLR and small video cameras are not designed to be used with sep sound systems such as zoom devices that in turn are also not designed to run in perfect frame sync with video cameras which are internally locked to frame rate.

[Daniel Epstein]

Sounds like Ana has traced it to an FCP Sequence Settings issue more than the cameras or recording drift we all know takes place.