Digital Recorder and Video Sync
 

I'm thinking about retiring my old MD recorder and using a digital recorder for weddings. I've been reading a lot about the Zoom H4's audio sync issues, but has anyone used the Sony PCM-D50 or the Tascam DR-1 with video and tested them for sync?

Basically what I want out of a unit is built in mics in case I can't plug into a board, mic and line level inputs, and decent sync over long periods with video. Hearing your experiences would be very helpful.

Depends on what you mean by "long periods." Even some of the most expensive professional recorders aren't able to maintain frame-accurate sync for more than 15 or 20 minutes unless there is some provision made to slave the clocks in the camera and recorder together.

We've begun to do more and more Catholic weddings so by "long periods of time" I mean like an hour or more.

Of the recorders I listed (or any I didn't) which seems to do the best job of keeping sync? Anyone know?

Without timecode sync connecting both devices, there will prety much always be a difference between the camera clock and the recorder.

One may be slicghtly slow and the other slightly fast, any way you won't have 'perfect' sync. Typically it is less than half a second/15 frames per hour.

At a wedding you won't be able to slate ;-) or even snap your fingers, so you have to eyeball it or find some common reference. Unfortunately I don't do weddings etc. so I don't have any tips/tricks that would work there.

George/

Not to hijack this thread too far but is that true of old school Nagras and film cameras? I was under the impression that they were not linked and stayed in sync forever.

They were linked and they always stayed in sync via a pilot signal between camera and recorder.

the least drift
 

Since we've established that the only way to hold sync past 20 minutes is to physically sync camera to recorder (via TC out) and this method is impossible for me, then which of the above recorders or any not listed with comparable options/quality/price seems to drift the least?

Or, to turn that question on its head, if all inexpensive digital audio recorders are going to have perceivable drift over an hour, how adept can you be at post sync correction?

My point is this - if you're going to have to do a correction anyways, does it really make a difference if its a 45 frame or a 180 frame correction?

(this is assuming that you have the capability to stretch & squeeze an audio track in your favorite post environment, you're not cutting and re-syncing every 10 minutes)

If all this sounds right for your situation, you'd then be thinking about which recorder in your price range has the features you want.

Yikes, 45 to 180 frame correction over an hour would be unacceptable. I've never had to compensate for clock differences in that range.

Less drift is better. But, there really is no known answer for the question which external recorder will be the closest match to my camera's clock...

There can be variances within brands. But, if there is a known problem w/ sinc with the zoom units...I would want to avoid going that direction.

I haven't used any of these units to make a recommendation: Looks like these are your options in the $300 - $600 price range. Choose wisely.

Tascam DR-1
Edirol R-09
Olympus LS10
Sony PCM-D50
Marantz PMD 660
Fostex FR-2 LF

Actually no, not by TC out (sorry George, but lack of timecode is not the culprit or its solution). Timecode performs the same function as a slate - it extablishes a single reference point in the picture and the sound so you can line them up in the editing timeline. The problem with sync is KEEPING them aligned for the duration of the shot. Even though they were recorded together, if their sample clocks deviate from each other they won't be the same length when they play back to a common clock in the NLE. Timecode controlled playback speed back in the days when audio was dubbed to magnetic perf for editing but it doesn't do that in modern file-based video workstations. So your timecode or slate lines up perfectly at the start of the clip but by the time it plays to the end they aren't lined up properly at all. To prevent that you need to take the video sync ("black-burst") from the camera and slave the audio recorder's sample clock to it. Or take wordclock from the recorder and generate video sync from it to feed to the camera's genlock input (if it has one). Or you use a common master clock or tuned Lockit boxes to feed genlock to the camera and wordclock to the audio recorder.

The least expensive solution I know of off-hand is to use the Tascam HD-P2 recorder. It accepts composite video from your camera output and slaves its sample clock rate to the black-burst sync signal embedded in the video stream. If you can't connect your camera to the recorder, it get's more dicey and none of the ones you mentioned will hold perfect sync for an hour or more. It may not be a total disaster - many NLEs allow you to make minor length adjustments without affecting pitch and if your audience is viewing the program on the small screen spot-on sync is less crucial than it would be for the movie theatre but it's definitely going to be a fiddly PITA to get it right.

If you can confidently sync the whole track in post, in one go, you don't really need to worry over small differences in the clock generators between models.
I posted a procedure for syncing in post here:

http://www.mfbb.net/myvideoproblems/...s-about25.html

a while back,using free programs.

If you have access to Audition, for example, it's even easier.

As the others have commented, the problem is likely to occur to some extent or another, whichever unit you go for.

Excellent article, Roger! As long as the correction needed is not too great, that's a good process. It is possible to avoid the problem in the first place but like many solutions to vexing problems, it ain't cheap to do it no matter which path you take.

Not so fast. My relatively inexpensive Sony MZ-M100 HiMD recorder holds synch with my cameras for over an hour. I know another frequent poster who has similar results with a different model Sony HiMD recorder.

On the other hand, I wouldn't personally guarantee these results for every Sony. I think that anyone who lays down the money for a digital recorder should plan on stretching or shrinking the audio file--and it's no big deal to do that.

My experience has been more positive. When I capture live events, I use Sony HDV cameras with up to 85-minute-long tapes. Sound is recorded to my Alesis HD24. Most of the time there is no noticable drift between audio and video. Sometimes (maybe 20% of the cases) I have to break a clip in multiple pieces and them of them around on the timeline, by ONE OR TWO FRAMES, to get them synch'ed again. Call me lucky, but the thought of having to deal with drift on the order of dozens or even hundreds of frames is just unbearable.

- Martin

Problem is, it's a crap-shoot. One day it'll be fine but another day it may be a problem. There are a lot of variables. Even the size of the screen where you viewing it effects the degree which it becomes an issue. There's an ad for a radio station I see on the tube almost every day that features short clips of several pop singers. In one clip, with KT Tunstall singing "Suddenly I See" while sitting on a tree branch, she's definitely out of sync by several frames - totally unoticable on a regular TV but glaringly obvious on the big screen projection set.