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Chroma key green screen, fast motion, and rendering in Sony Vegas
Dear all,
I’m experimenting with Sony Vegas (Pro 10) and a green chroma key color that I painted on a white surface. I’m having trouble with the rendered result though. I’ve uploaded a small video on Youtube with the result:
https://www.youtube.com/watch?v=slxWwP-v3-E
Everything looks fine in Vegas preview window when stepping through each frame (with the arrow keys), but the rendered file ends up with a kind of trailing green after-image of my hand when moving it in front of the green screen (pause the video a few times and you’ll probably see it, or watch it in 1080p). Sometimes it looks kind of like those old 3D-movies where the image is doubled and one of them is green.
This is not a shadow from the lighting, the green screen is properly lit. Rather it seems that I have a faulty setting somewhere when I render, but I can’t figure out what. English is not my primary language, thus searching for an answer has been fruitless so far (probably using the wrong words).
The project setting I am using is “HD 1080-60i (1920×1080; 29,970 fps)” because my camera, the Panasonic HDC-SD60, outputs 1080-60i. I’ve tried multiple rendering settings all with the result shown in the video. In this particular instance I used “Sony Vegas AVC” and “Internet 1920×1080-30p”, but I’ve also tried “Internet 1280×720-30p” and various other 1080i, 1080p, and 720p formats. Any ideas what the problem could be?
Sincerely,
Linus Leonard -
3 Replies
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First, double check that you dont have any extra keframes
at the bottom of the chroma keying window.
And using the chroma blur filter can also help reducing that trail,
along with smart color correction.Steve Rhoden
(Cow Leader)
Film Maker
Filmex Creative Media.
1-876-832-4956 -
I think that you are looking at encoding artifacts. You likely have a ring of green around the hand in the foreground because there’s no spill suppression in the Vegas chromakeyer. Frame-by-frame on the timeline doesn’t introduce encoding artifacts, but when you have a GOP of frames in the encoded video the decoder has to guess what to put in the predictive frames based on the last i-frame.
If I am right, go to the “render as” custom settings and set the encoder to i-frame every 1 frame. The file will be huge, but it would verify my guess.
Steve Mann
MannMade Digital Video
http://www.mmdv.com -
Try setting your project settings to progressive, de-interlace method, interpolate. Also render as progressive. It may be a little stuttery due to the fast motion of your hand. I always de-interlace when keying. It looks like your shutter speed is to slow, causing some blur. Blur doesn’t key very well.
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