rendered mask doesn't line up.

paullinstrot wrote on 1/22/2006, 6:45 PM

I worked hard cutting out a person from one shot using mask in "Even Pan/Crop", however when I render the video, the area I cut around applies to the frame before or after and theirfore the movement is including some of the shots backgrond which is ruining the shot. Does anyone know what is causing this and how I can get it to render right. thanks.

Comments

PeterWright wrote on 1/23/2006, 12:45 AM

If the person is moving, the only way to keep the mask fitting the person is by keyframing the mask on a frame by frame basis.

Depending on the amount and type of movement, this may not be practical - better to use After Effects or similar that has motion tracking.

paullinstrot wrote on 1/23/2006, 12:53 AM

I have already keyframed the animation, and spent many hours working on this one shot. The shot it complete, and looks the way I want it to in the preview window when I use the arrow keys to go through it frame by frame. However, when I render the clip as an AVI file, and then open it up, the mask/keyframe animation is a step behind or ahead, so that when I look at a frame with the mans arm moving, there is a cutout of where his arm should fit in but with only half of his arm and the rest being the original backround that was behind him.

Sol M. wrote on 1/23/2006, 2:08 AM

I honestly haven't done much rotoscoping in Vegas, but at least with compositing apps like After Effects, Combustion, Commotion, etc., if you can ever avoid it, don't rotoscope frame-by-frame as it can introduce jitter. Keyframe interpolation (when keyframes are spaced apart) helps to smooth out the movement of the mask, so starting by keyframing the on the large movements and then working down to the finer movements from there is recommended. However, depending on the footage, frame-by-frame rotoscroping is the only way to achieve the effect.

As for your problem, what is your Video Preview Quality on your Video Preview window set to (Preview, Good, Best, etc.)? I've noticed fairly large variances in mask placement when working in one quality mode and then switching to another (e.g. working in Preview and then switching to Best).

Are you seeing this offset only when rendering, or also when you change Preview Quality?

Grazie wrote on 1/23/2006, 3:13 AM

Paul?

Is none of it in step? If some of it "appears" to be in step, and as you say the "arrow" keys shows you are on-beam, then I'll have a stab at this one.

RATES of CHANGE: The "RATE" Vegas - quite rightly - allows us to get through a set of keyframes can be pre-set: Linear; Fast; Smooth; Slow, Sharp and Hold. Now each of these "Rates" do have a dramatic effect on the way anything starts, moves, continues and finally stops at the other end.

2/- SAMPLE: I've driven myself nutz with a perfectly composited list of 100 rolling names, horizontally rolling across the screen. The only problem was, I was picking up an acceleration to the middle of the run - and yes around the 50 name marker - then they would decelerate to towards the end and then finally be back on sync.

3/- PROPOSITION: I bet your movements have a different rate of move. And this is what is being "uncovered" when you see some of the footage you speak of. AND just by going through frame by frame you wouldn't pick this anomaly up. Well, it aint an anomaly, it is Vegas DOING exactly as it should.

4/- SUGGESTION: My advice would be to experiment with the "other" rates of movement. See if this will help. You need something to keep your Mask in "step" with the underlying actual video.

Possibly when you "arrow" preview you DON'T see the keyframe to keyframe RATES of change. Thinking about it, Vegas would be a bit silly if it did! So my guess, at Keyframe level, you aren't/wouldn't be made aware of the differential in the rates of change of Linear; Fast; Smooth; Slow, Sharp and Hold rates - yeah?

Hope this helps,

Grazie

songsj wrote on 1/23/2006, 3:21 AM

I ran into a similar problem however I was working with a Quicktime slide show a friend gave me to play with. I split each picture carefully then stretched them to fit my time line and everything looked fine in ALL preview modes. However when render to .avi or any other format I got part of the quicktime slide show bleeding through the main track. I posted here for suggestions here and got none. I have not gone back and played with it much but I never did get it figured out. If you do please post as even though our situations are different, I think the cause and solution may be the same.

thanks