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Cassette Tape Recording sync with Video Issues

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Drew Angle
Cassette Tape Recording sync with Video Issues
on Feb 26, 2012 at 11:55:35 pm

I'm currently shooting a documentary on 7D (1080p 24p) and as an artistic choice to suite the subject we are capturing audio externally with a Radioshack Cassette Tape Recorder (CTR-122; CAT. NO. 14-1129).

We shot slates with claps for every video clip as a way of syncing in post, but after our first test we realized that there is an issue of timing and frame rates between the tape recording and video recording. The footage is being edited in a 23.98 timeline in FCP. The audio was digitized in .aiff files. I'm assuming this has to do with the recording speed of the cassette player - which I'm unable to find in terms of frame rates. Any suggestions for a way to convert the tape recordings to something that would sync with 24p?


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Steve Kownacki
Re: Cassette Tape Recording sync with Video Issues
on Feb 27, 2012 at 12:37:28 am

Are you simply looking for that "cheap cassette recorder sound"? Why not record with a proper recorder and then cheese it up to sound the way you want?

I can tell you that consumer cassette players, especially when using batteries, will MAYBE play back at the same speed and if you are recording on one machine and playing on another, you will have significant drift and you will have many edits to bring it back into time.

2nd suggestion is to come out of the headphone jack & into your mac and capture at the same framerate as your sequence.


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Andrew Rendell
Re: Cassette Tape Recording sync with Video Issues
on Feb 27, 2012 at 11:04:26 am

A big part of the sound of a compact cassette is precisely the speed instability which leads it to not be able to stay in sync with a video feed. IIRC, Sony did make a crystal-locked cassette recorder at one point (sometime in the mid 1980's) which would stay in sync.

Once you've recorded it into the computer, that audio will always play back at the same speed, as you've basically frozen the speed variables of one particular playback.

There's not much you can really do apart from play the tape back in the same machine that recorded it and perhaps do it a couple of times to see if one playback runs at a closer speed to your video than another. As Steve says, you'll probably have to do quite a lot of editing to get it to track the way you want it to.

ETA: I see that the Sony WM-D6C does still come up on ebay. I guess that would be better than the Radio Shack recorder if you can find one in very good condition.

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Richard Crowley
Re: Cassette Tape Recording sync with Video Issues
on Feb 27, 2012 at 4:01:20 pm

Cassette machines (well tape of ANY kind) were NEVER capable of what we think of as "sync sound". Extraordinary (and expensive) means were taken to synchronize tape to film/video. Most of that technology doesn't even exist anymore because use of analog tape for production recording has essentially gone extinct on this planet.

You must choose between your "artistic choice" of using a cheap, primitive, antique recorder vs. synchronized sound. It is as simple as that.

Digital recording technology, in addition to being "cleaner" than analog, also has the advantage of being much more STABLE, making the need for gen-lock, time-code, etc. not as mandatory, especially for shorter (<10min) shots.

Yes, there are probably still people using Nagra reel-to-reel machines for sync recording, but that audio solution probably costs more than your camera. And, of course, there is no sync capability in your camera. And it doesn't sound like a cassette machine, either.

IMHO, your desire to use a cassette machine for sync production recording is simply not practical.

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