Incredible shrinking track matte key

Question

Hi,I have 3 layers of the same video aligned on: video 1 (background), video 2 (track matte key) and video 3 (HSL secondary).  My goal is to be able to make Lumetri color changes to video 2 "sandwich filling layer" which  will be viewed through the masked off portion of the top layer.  On the top layer, I keyed out the blue sky using White/Black masking in HSL Secondary.  On the "filling" layer, I added the track matte key set to Video 3 and Matte Luma.  For this demo, I set the exposure way down on this layer in the basic Lumetri control. Result:  if I leave the scale of the top (mask) layer set to 100%, the track matte key is quite a bit smaller than it should be.  If, however, I set the scale of the top layer to exactly 102.1%, the matte looks much better.  I am using the 102.1% scaling of the top (mask) later as a workaround and it works pretty well.  The keying holds up while playing a test clip and even matches if I scale up the test clip.  Please see attachments.  Any observations or advice on this phenomenem will be greatly appreciated.  ZafferTop layer scale set to 100% Top layer scale set to 102.1% Ivy walk test video_01 (day) Ivy walk text video_02 (night)

Michael Grenadier · Accepted Answer

Hi Neil,News Flash!  I tried the same stacking/matte track key procedure with another movie clip.  This one was recorded live (don't know what camera) of people dancing, and it came to me as MP4.  The clip I'm having the trouble with  was a screen capture made with Snagit -- also an MP4.  Do you think that could have made a difference?  Screen capture vs recorded live? This might also be of interest.  I tracked down a video by someone who also had the shrinking track matte key problem.https://www.youtube.com/watch?v=T1XnJmUfI_M. In his his video he recommends putting a Turbulent Displace on the track matte key layer and setting the amount down to zero.  This worked on my clip, but the Turbulent Displace effect used a lot more computer resources than just increasing the scale of the top clip.  Any thoughts will be appreciated.Zaffer  just a shot in the dark, but screen capture clips are often variable frame rate which can cause all sorts of weird issues.  use mediainfo to determine whether your source is variable or constant frame ratehttps://mediaarea.net/en/MediaInfo/Downloadif it's variable use handbrake to convert to constant frame ratehttps://handbrake.frand here's a tutorial on how to use handbrakehttps://www.youtube.com/watch?time_continue=34&v=xlvxgVREX-Y

R Neil Haugen · Answer

I always Alt/drag the clip up to V2, then Alt/drag that to V3. I've never had a scaling issue, like what you seem to have, and that puzzles me. Neil

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