Time code float at 29.97?

taudronis

taudronis

New member
Alright, I think everyone can agree that audio leaves a bit to be desired from the 7D, so I ordered a Zoom H4N.

In researching it though, I came across this:

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I AGREE


Ok, so 7 frames after 10 minutes... you may say, "not that bad." But hey, we're not in analog land anymore. That shouldn't happen.

So, I look down a bit to the comments, and see this:

I did the same test with the Canon EOS 7D shooting with 25 fps and the Zoom H4N recording with 48 kHz 24 Bit. Over a 11 minute duration it was in perfect sync, not 1 frame was shifting! Lucky me! :o)
Click to expand...
(posted by "doowatchalike"... nice name by the way)

If that's true, that would mean that the problem isn't the H4N... it's the 7D!!! That would mean that the timecode when running 29.97 is really more like 29.969.

Sound picky? Well, it's just that it kind of freaks me out that it just isn't quite right. I haven't received my H4N yet, but once I do, I intent to test out every resolution and framerate the 7d has to offer.

I'll keep you posted.

My question though is... has anybody else run this test?
 
testing timecode drift on the Canon 7D

testing timecode drift on the Canon 7D

I did this test by putting LTC (out of a running smart slate) on the audio track of the Canon 7D. I then shot video of that smart slate with open sticks (displaying timecode) for the longest take possible (12 min I think). I downloaded the footage and took the audio output of the computer (containing the recorded LTC) and fed it back into the smart slate (using it as a TC reader). I froze the moments in time by snapping shots of the computer screen and smart slate while playing back the footage at beginning middle and end.

Conclusion: The audio was immediately 4 frames off from the video. This offset was consistent throughout the duration of the clip with <1 frame drift in that room temp. setup.

Summary: The slight timecode drift is good enough for government work.
 
My test was done at 23.976.. sorry I missed that little detail. Attached is a screenshot.
-RK
 

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Cool. So at least it's consistent at that framerate. Thanks for the post! (and I'm jealous of your smart slate... been aching to get one)
 
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