Tuesday, February 14, 2017

Re: [Avid-L2] Re: QC Flipped Me Off!! Uh QC said my Flip Is OFF!!!

 



Meanwhile I've had a look at the images too.
The original is fine.
 
When I apply a 180 degrees Z rotation in FrameFlex,
the image gets 2 pixels shifted to the top and right. No scaling is applied, it's just shifted by two pixels.
(Or even 3 when I set it to Pillar / Letterbox)
 
Removing FrameFlex and adding a classic Flip-Flop from the Effects does give the expected result.
 
IOW, remove Frameflex in the bin, refresh sequence and add Flip-Flop, problem solved...
 
hth,
 
 
Bouke
 
VideoToolShed
van Oldenbarneveltstraat 33
6512 AS  NIJMEGEN, the Netherlands
if you want to send me big files, use this:
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----- Original Message -----
Sent: Tuesday, February 14, 2017 4:30 AM
Subject: [Avid-L2] Re: QC Flipped Me Off!! Uh QC said my Flip Is OFF!!!

 

Upon further investigation if I export a still of the flipped and the unflipped shot and then make them layers in Photoshop I can clearly see the black edge on the left and right when I put the flipped shot on the top layer and vary opacity and zoom in on the left side or bottom.

Not the question is does this indicate a broke in Frame Flex Rotation or is it an indication that active video line ends early relative to the SAV.  Perhaps the camera might have an issue but I think it's the flipping that causes the discrepancy. 

Tomorrow I will do the same stills export with a different camera to see if it behaves the same way.  If it does then it points to the flipping in frame flex.  This is Panasonic 4096x2160 material shot AVC Intra 4:2:2 YUV.



---In Avid-L2@yahoogroups.com, <bigfish@...> wrote :

On two of my recent 4K shows QC has flagged Framing Errors at the left and bottom of the screen.  I was thinking there was one bad camera but I realized today the shots being flagged were on a jib and the camera was mounted upside down.  The shots have been flipped 180 degrees in Frame Flex.  Unflipping the shots and the left and bottom show no framing error. 

The issue is really small like a line or two at most on the bottom and even slighter on the left.  I don't really think its a viable issue but blowing the shot up 1 Pt makes the edges match.  I think the only reason QC flagged it is the comparison between un flipped shots and the flipped ones.  At the cut point you can just make out the slight change.  These images are 4096x2160 so they appear as letter boxed on my 4K OLED LG panel.

In the old days I would call it a slight difference in horizontal and vertical blanking where there is a bit more blanking at the end of the scan line but now with SAV and EAV shouldn't everything just flip perfectly.  This is really a small difference but QC has flagged it on two shows.

I've set my LG OLED panel to the "Just Scan" setting that shows more picture.  I would call it underscan mode but this is a consumer monitor so I'm wondering if the "Just Scan" might be one of those modes that keeps the center of the picture normal but stretches out the edges.  I've seen Married with Children SD reruns that have been scaled that way. The picture doesn't seem to be distorted like that so I think the setting is just showing the edges of the frame.

The bottom line is why is the end of the active line to EAV different from the SAV to beginning of Active line and the loss of a line or two in 4K at the bottom of the screen points to a lack of symmetry in the vertical blanking area.  I'll have to look at how the top of active video can be different than the bottom of active video.

Am I wrong to thing the 180 degree flip should be perfect and undetectable without a blow up?
 
John Moore Barking Trout Productions Studio City, CA bigfish@...




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Posted by: "Edit B" <bouke@editb.nl>
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