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Old May 30th, 2009, 12:02 AM   #1
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Time Accuracy of Small Recorders?

Hello,

I used to use a M-Audio microtrack to record audio from mixer boards for plays and such, but when I went to align the audio in post, the audio would eventually go way out of sync. So my solution was to get an Apogee Mini-me A/D converter with spdif out to the microtrack...thus using the better clock in the mini-me and that solved the problem. But ofcourse getting the mini me and microtrack was over $1000...so the question is, has anyone recorded long venues with the $300 or so recorders and experienced the time drift? I'd love any feedback on which ones have this drift and which do not, if any? Thanks in advance!

Bill

Last edited by Bill Brock; May 30th, 2009 at 12:03 AM. Reason: clarity
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Old May 30th, 2009, 12:47 AM   #2
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I can't answer your question, but I would like to ask a couple:
How long does it take the Microtrack to go out of synch? How is the MicroTrack synch for 5-10 minute takes?

I'm going to use a MicroTrack on an actor instead of a wireless, and I'm wondering if I can get 5-10 minute takes to synch. Obviously, I can resynch between cuts in the final video, but I would still like to get an idea how long I might expect to go without problems.
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Old May 30th, 2009, 01:16 AM   #3
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Time accuracy issues

You should be fine with short runs. My sync issues were really apparent with 40+ minute runs. I could probably use the time stretch functions of some DAW's to fix it, as you could if you have issues with sync, but I like it right from the start.





Quote:
Originally Posted by Jack Walker View Post
I can't answer your question, but I would like to ask a couple:
How long does it take the Microtrack to go out of synch? How is the MicroTrack synch for 5-10 minute takes?

I'm going to use a MicroTrack on an actor instead of a wireless, and I'm wondering if I can get 5-10 minute takes to synch. Obviously, I can resynch between cuts in the final video, but I would still like to get an idea how long I might expect to go without problems.

Last edited by Bill Brock; May 30th, 2009 at 01:19 AM. Reason: removed unsolicited advice
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Old May 30th, 2009, 03:11 AM   #4
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It depends on the camera used as well as the recorder. The idea is that their clocks must run at the same rate and unless you are able to use a common timebase, something difficult to do with consumer recorders and cameras, the degree to which the two clocks match is a going to be a matter of luck. Variables include the mix of camera and recorder makes and models, the specific units that came off the assembly lines due to manufacturing tolerances, and even their different drift with changes in the ambient temperature at the location.
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Old May 30th, 2009, 08:48 PM   #5
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As Steve says, there are a number of variables involved.

I posted a possible way of trying to help the situation a while back
My Video Problems :: View topic - Synchronise external and camera audio tracks.
for a friend who was using a separate audio recorder, for his wedding work.

Obviously not as good an option as using a common timebase, as Steve mentions, but it can help if the budget doesn't quite stretch to full pro kit!
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Old May 31st, 2009, 11:00 AM   #6
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Time sync

Thanks Roger,

That's a great workflow you have there and easier than figuring out the time stretch coefficient for each item recorded.


Quote:
Originally Posted by Roger Shore View Post
As Steve says, there are a number of variables involved.

I posted a possible way of trying to help the situation a while back
My Video Problems :: View topic - Synchronise external and camera audio tracks.
for a friend who was using a separate audio recorder, for his wedding work.

Obviously not as good an option as using a common timebase, as Steve mentions, but it can help if the budget doesn't quite stretch to full pro kit!
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Old June 2nd, 2009, 12:08 PM   #7
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This is something I've experienced with every long recording I make. I record church services, beauty pageants, and such. I've used an iRiver H120, H320, Sony PCM-D50, and line in to my laptop so it's not an isolated issue.

I leave the recorder running from start to finish, use LP setting to record, and then sync. For a 60-90 minute segment I'll be about 1 second off by the end. With Vegas it's a breeze to correct.

Even though you're recording the same event the separate devices you are using have different internal parts made by different manufacturers. It's not any surprise they might drift some.
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Old June 2nd, 2009, 12:58 PM   #8
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I use a Sony PCM-D50 along with my Canon XL H1A and XH A1 to do dance recital, plays, etc. It pretty consistantly is off by just over 3 frames each hour. I've got the cameras set to 30p and the D50 is recording at 48Khz 24bit.

I've also recorded sound directly to my laptop using a mixer with a firewire port and Vegas as my capturing software. That set up yields a little more time shift to the amount of about 6 frames every hour.

I use Vegas as my NLE and as Stan said it is a breeze to correct.
Garrett
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Old June 2nd, 2009, 09:36 PM   #9
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I came up with a little rick of going to the last part of the audio tracks and creating a loop region between to spots where it drifts. Then I drag the loop region to the end of the track and use it to stretch/shrink the exact amount I need.
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Old June 6th, 2009, 12:19 AM   #10
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Going back to your original question, we have had remarkable success with the Edirol R09 --now succeeded by an upgraded model at the same price --- keeping perfect synch with Canon HV20's over a 10-minute or so interval. Sometimes a reporter will do a press conference and set the Edirol on the podium, then record with a small Sennheiser shotgun on the camera as well. The tracks align perfectly in my experience, aided by some key event to synch to --- a loud "accidental" cough seem to help ;)--- I dont' know how long this close tracking will keep up as we haven't had occasion to test if for long intervals, but in the course of a single clip it works a treat. HTH / Battle Vaughan/miamiherald.com video team
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Old June 6th, 2009, 01:44 PM   #11
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I second that vote for the Edirol H09. I have the HR model. and it has kept perfect sync up to an hour for me as long as I use 16 bit 48khz WAV. It also has a great limiter that works well for unexpected loudness.
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