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Old February 13th, 2010, 09:17 AM   #1
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DvcAM50SQ and Dvcam25SQ. Differences?

What is the difference between Dvcam50SQ and Dvcam25SQ?
I have ex1r and i have record a wedding with Dvcam50SQ format.
I have a problem in the editing suite(AvidMC 4.0.3). In the timeline preview window everything is ok.
But on the output the picture is shaking!!!! It is something like watching one layer and after the other.
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Old February 13th, 2010, 04:29 PM   #2
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50 probably means 50i - i e interlaced video. Possibly you could be seeing quick movements of the camera on the interlaced output to the monitor that are not noticed when watching only 25 fps ont he computer monitor.

How would you describe the "shaking"? I don't understand what you mean when you say "watching one layer and after the other". Could you possibly be outputing the fields in reverse order?
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Old February 13th, 2010, 06:12 PM   #3
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fields reversed?

The difference is that 50 means 50i indeed and 25 means 25p (progressive). In SD they are both saved as interlaced, but 25 looks like progressive because both even and uneven lines are captured the same time.

The '2 layer look' you discribe, sounds to me as if the interlaced fields are reversed. Upper field first instead of lower field first makes footage look shaky, because instead of 1,2,3,4,5,6,etc you see 2,1,4,3,6,5 (uneven numbers are uneven fields, even numbers even field).
I've seen this once years ago during my internship.

Good luck & let us know how you solved the problem!
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Old February 13th, 2010, 07:33 PM   #4
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PAL DVCAM is lower field first - the format the EX1R records SD video in - when you import into Avid make sure you set the the field order to lower field first. Please ensure your encoder that you use to encode to DVD compatible files is set correctly as well. You won't see field errors on the preview window because a computer monitor is progressive and the NLE only plays every second field or combines the fields into full frames.

You can easily determine if this is the problem in Avid - map the 1 field advance key from the command palette to a source monitor button - call up a source with lots of movement in it and step through the fields one field at a time - the movement will go forwards but then reverse on the next field for each alternate field if you have the wrong field order. Correct field order movement will all be in the right direction.

Do not record in 25P unless you know what you are doing. 25P requires attention to pan and zoom speeds etc or you will see progressive "stuttering".
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