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Ruby Gold
"blemish" on footage
on Apr 6, 2005 at 11:50:43 pm

I'm looking at interview footage I shot with my GL2 in PPro 1.5. It looks good, but in one scene in one frame a blemish appears that looks sort of like a small circle of "fried pixels." Viewed close-up it's an 8 x 8 square of black, white and grey pixels incongruent with the rest of the image. It's only on one frame.

Does anyone know what this is--what caused it--and how to avoid it? Thanks-


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Matte
Re: "blemish" on footage
on Apr 7, 2005 at 4:23:30 am

It sounds like a "drop-out" and you avoid it by not using video tape.
Drop-outs are just a fact-of-life with magnetic media.

Most of them these days are completely masked by error-correction in digital formats, but very occasionally one will be severe enough to show.

Just be happy you're not shooing on analog BetaCam.


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Matte
Re: "blemish" on footage BTW
on Apr 7, 2005 at 4:26:13 am

BTW, you can "fix" this in editing by covering the "blemish" area with a matching section of the previous frame (or next frame) that is "clean".


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Ruby Gold
Re: "blemish" on footage BTW
on Apr 7, 2005 at 4:45:32 pm

Thanks for the response--your fix was just what I had in mind--I just didn't understand why it was on there in the first place--hadn't experienced it in other shoots.

Also, no dropouts "registered" when I was capturing in PPro 1.5--is that a different kind of dropout? And, there's absolutely no way to avoid them, eh?



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Ruby Gold
Re: "blemish" on footage BTW
on Apr 7, 2005 at 4:50:09 pm

Thanks for the response--your fix was just what I had in mind--I just didn't understand why it was on there in the first place--hadn't experienced it in other shoots--and if there was some thing I could do to avoid them.

Also, no dropouts "registered" when I was capturing in PPro 1.5--is that a different kind of dropout? Lastly, what did you mean when you said that most of them are "completely masked by error-correction in digital formats?" And, there's absolutely no way to avoid them, eh? Damn...

thanks again-



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Matte
Re: "blemish" on footage BTW
on Apr 7, 2005 at 9:34:26 pm

[Ruby Gold] "what did you mean when you said that most of them are "completely masked by error-correction in digital formats?""

It means there are AWAYS drop-outs over the course of virtually any tape.
In analog systems, the "mask" is usually very visible, in digital formats the error-correction completely covers maybe 99.5% or more, so they go unnoticed.

As to the software "registering" a drop-out:
At the digital import level, unless the TimeCode stops or the entire image is lost to a head-clog or severe tape problem (i.e. a crease) the computer doesn't even "know" there IS a drop-out.
Only to your EYE might there appear to be something amiss in the video.

And, trust me, if its just a frame or two with a "blemish", do the "dance of JOY"!

We who have come from analog BetaCam (and earlier) know what simple tape drop-outs can truly "do" to a video image.

Again, without actually SEEING your "blemished" tape image, I am only speculating about it being a drop-out... but it sure sounds like that's what it is.


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