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Weird Black Slivers

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Derek Natzke
Weird Black Slivers
on Jun 24, 2008 at 7:16:40 pm

My name is Derek Natzke and I am currently working on digitizing BetaSP content with a SONY UVW_1800 deck into Final Cut Pro 5.1.4 thru a KONA 2 card. My issue occurs as I'm digitizing and appears to retain the issue after I have digitized the footage. Slivers of black appear on the left and right sides of the image (10-15 pixels in width), once it is loaded into the viewer they are seen. Now, when I Capture DV footage vis firewire, that doesn't occur. These black slivers reside outside of action safe and do not show up on an NTSC monitor. However, when I export the footage out as a QuickTime file, the bars are seen. QuickTime allows the viewer to see everything. I have digitized into the FCP as 8 Bit (720x486) and DVCPRO50 (720x480), and obtained the same results. From my understanding, the image on a BetaSP tape has more information recorded to it, so it confuses me as to why I am getting these black bars, instead of more image. Please explain. Is there a capture setting incorrect?


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gary adcock
Re: Weird Black Slivers
on Jun 24, 2008 at 7:51:28 pm

[Derek Natzke] " My issue occurs as I'm digitizing and appears to retain the issue after I have digitized the footage. Slivers of black appear on the left and right sides of the image (10-15 pixels in width), once it is loaded into the viewer they are seen."

My guess is what you are looking at is the LTC time code in the overscan area of your footage outside of the picture safe are, the reason you do not see this in DV footage as the frame size is smaller (720x486 vs 720x480 and the DV footage import does not allow you to see the overscan area.

gary adcock
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Carsten Orlt
Re: Weird Black Slivers
on Jun 25, 2008 at 4:23:01 am

what your seeing is what is called blanking. Basically it is the video beam being switch off at the end of a line to be able to jump to the beginning of the next line - making the picture black on the left and right (I'm no techo so this is a very simple explanation).

Different video formats have different blanking times and therefor have different size black on the left and right sides.

BetaSP has a larger blanking and there is nothing you can do about that!

For broadcast it doesn't matter because as you rightly say it is well within the safe areas. Some broadcaster though do not accept anymore the wider blanking of BetaSP and the only way to get rid of it is to slightly zoom into the picture until the left and right black sides disappear. Of course this will affect the picture quality but again nothing you can do.

If you just outputting to quicktime movies say for the web or CD-Rom you could try to use compressor and apply a left and right crop to to the output size of your movie. I haven't tried this so I can't give you specific instructions but it should work. Of course this will give the resulting quicktime slightly odd pixel x pixel dimensions, but because quicktime player adjust its window to whatever size the movie is it doesn't matter.

Hope this will give you some leads to evaluate your options.

Cheers

Carsten


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Carsten Orlt
Re: Weird Black Slivers ADDITION
on Jun 25, 2008 at 4:36:29 am

I should add to the statement that Broadcaster do not accept the wider BetaSP blanking:

This is only the case if your mastering to a format that has less blanking then BetaSP, e.g. Digital Betacam

If your mastering to BetaSP it doesn't matter because the recording machine will add the standard BetaSP blanking to whatever signal you will feed it, even if has less blanking (e.g. DV)

You can easily show the effect by playing out DV originated footage to the BetaSP and recapture it. Now it will have the same blanking as the BetaSP originated footage.

Carsten


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