Event Pan/Crop: "jerk" at end of motion

john-beale wrote on 10/30/2007, 9:04 PM

I'm using Vegas 8a. When I use the Event Pan/Crop control to do a slow zoom into the frame and slowly come to a stop, there is a small sudden jerk at the very end of the movement. It is small, maybe only one pixel, but it is quite visible and is not acceptable- how do I fix this?

It looks like some kind of round-off issue, eg. the last frame of the movement is not "anti-aliased" and jumps one full pixel.

(WOW! quite a litle earthquake here in Mtn.View CA 8:06 pm PST)

Comments

john-beale wrote on 10/30/2007, 9:46 PM

solved it. The motion was a zoom and a rotation from -11 to 0 degrees. Rather than ending at a rotation of exactly 0.0 degrees, I set it to end at -0.1 and now it is smooth.

Note to Sony: it would be nice if this kind of workaround wasn't needed.

xberk wrote on 10/30/2007, 10:01 PM

Can't reproduce this problem. What's the interpolation curve of the keyframe on your zoom ? Linear? Fast? Slow? - Anything else going on? -- My zooms seem to stop without any "jerk" .. Maybe I'm just not seeing it.

Serena wrote on 10/31/2007, 12:12 AM

Did you set to "smooth" and adjust "smoothness"?

Grazie wrote on 10/31/2007, 1:01 AM

Make very sure you don't have any "rogue" K/Fs lurking under or very near to the issue? - I've overlooked this at times. Also, confirm you don't have any wayward Track Motion acting on the Event.

I was concluding a piece yesterday, and for the life of me, I couldn't identify just why I had a set of 4 - 2x2 - videos seemingly stubbornly refusing to centre themselves. Took me at least 20 minutes to pin it down.

Reason? I had a ONE residual Track Motion Keyframe from a previous experimental "sketch-out" I had introduced. Removed KF and the Event's 2x2 centralised.

Reason? Pilot Error! - not SONY's

Regards,

Grazie

JJKizak wrote on 10/31/2007, 6:51 AM

I made a suggestion to Sony about the "rogue key frames" to have some kind of indication like "blinking", "color burst", "symbol change", etc to show that you have something behind your key frame.
JJK

john-beale wrote on 10/31/2007, 10:43 AM

Thanks so much to everyone for the comments and suggestions. In this case, I do not think my problem is a "rogue frame" or pilot error. Can you please try this sample .veg (for Vegas 8) and see what you think? The zip file contains one sample bitmap PNG as well as the veg. The motion definitely jerks at the end, at least on my system.

http://www.bealecorner.com/D30/misc/Jerky-Stop.zip

If you preview at full resolution, the jerk may be hard to see unless your preview window is maximized. At draft resolution, the jerk is very big, 20 pixels or so.

Serena wrote on 10/31/2007, 11:49 PM

Yes, there is a vertical shift (or near vertical). Can't see any reason for it.

john-beale wrote on 11/1/2007, 11:09 AM

Thanks for confirming Serena! glad to hear it's not just me.

xberk wrote on 11/2/2007, 5:16 AM

>>glad to hear it's not just me.<<

I see it -- especially in Draft mode -- But don't you get this same little "jerk" at the end of any rotate for any video image as those little jagged (or fuzzy) edges snap into place on the horizontal? I think the lower the resolution, the worse it gets. I don't think it's Vegas .. wouldn't you get this with any NLE or program that rotates an image or text when viewed at low resolution (like draft mode preview?) ..

Serena wrote on 11/2/2007, 6:19 AM

It's there at high resolution. The very last frame (at the key frame) after the rotation is finished. The figure does a little translational step. Step through frame by frame. Having said that, I'm wondering if this is an interlace artifact. The last step is to the last field rather than the last frame. Sounds a bit unlikely.

farss wrote on 11/2/2007, 6:56 AM

It is quite annoying.
I think I can see what's happening and I've had a similar problem.
Vegas calcluates the interpolated values in event pan/crop to only 1 decimal place. In this case you're using X and Y scale and rotation. Vegas has to do some maths on all those values to determine the position of each pixel, notice have the vertical line don't quite stay straight either, the lines sort of wobble around, most noticeably when they're almost vertical, I think here we're seeing the effect of all the rounding errors adding up and there's no anti-aliasing.

One solution I found was to not use even pan/crop to do both rotation and movement or scaling. This might or might not solve your problem. Use event pan/crop to do the zoom and use track motion to do the rotation, see if that help.

Bob.

john-beale wrote on 11/20/2007, 8:59 AM

Just a followup. After some back and forth, Sony agreed there is an issue, and is apparently working on it. Got message below from Katy T. at Sony today:

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Thank you for contacting Sony Creative Software.

Thanks for your very clear and concise description, it was most helpful in getting the problem identified and escalated.
Because this incident involves very detailed technical aspects of the programming and design of our software, I will be consulting with our Development and QA team to try and resolve this issue.

Please understand, that because this issue is so technical in nature, and because these other teams have a rather large workload, it may take some time to solve this problem. I will be setting this incident to development status during this time and will update this incident once I have further information from them. Thank you for your patience while we continue to research this matter.

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craftech wrote on 11/20/2007, 10:23 AM

Way to go John. Thanks.

John