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png files jump all over the place!
Here we go. I took an old home movie converted it to mpeg2 and have it in my timeline. I thought it would be fun to add ‘lightsaber’ png pics to the project to replace some sticks we were holding. I used pan and crop to move the png’s each frame and it seemed to work ok.
I can play the project and it runs smooth in the preview window, even full screen. When I render it is where the problem comes in.
It’s not high def or widescreen, I have it set at dvd architect ntsc video stream in the 4:3 ratio, 720x480x32, 29.970.
In some places, the ‘lightsabers’ are seen flashing in other parts of the scene for brief seconds. I check the pan and crop and everything is in order. Sometimes I see one ‘flash’ way to the left or to the right where I know for sure I never panned it there.
The scene is pretty fast so maybe it’s not keeping up somehow? All the other png pics I added to the film seem ok but they are in slower scenes with not a lot of movement.
Any idea’s guys?
Thank You. -
5 Replies
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What happens when you drag the playing cursor slowly along the timeline? Do you see the lightsabers move smoothly as expected?
I’m wondering if somehow your keyframing isn’t messed up…
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https://www.davelozinski.com
https://www.davelozinski.com/DemoReel/
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It moves smooth. The only time I see the jumping and flicker is when it’s rendered.I just tried re-doing a short scene and the same thing happened again. It’s like the ‘lightsaber’ is rotating or not keeping up in the scene between frames. there is a lot of movement in the shot so I had to do quite a bit of pan/crop and some resizing.
I see nothing wrong in the preview window and it looks good. It just seems that in the rendered film it’s like the png is trying to rotate every few frames and I’m seeing the flash of it doing that.
I’m running Sony Vegas HD PLatinum Production Suite and my computer memory is more than enough.
The process I use is to place my png picture file above the video track in a seperate track and stretch it the lenth of the clip, then I start at the beginning and pan/crop until say, it goes out of frame. I’ll split the png clip there, and remove that part until it returns to frame, and return to panning.
In my whole film I do have other png files on the same track a lot further along in the timeline, but they seem okay. Again, it looks good in preview. -
Your first problem is that you have MPEG2 on the timeline and you are trying to do frame accurate placement of objects. Unfortunately, only one out of every 15 frames in MPEG2 is accurate. The rest are only deltas which may display differently depending on if you scrubbed forward or backward through the timeline.
The first thing you need to do is to make a DV AVI file from you home footage and edit with that. You don’t want to be editing MPEG2 which is already highly compressed compared to DV and subject to loss when re-rendering.
The next thing that could be the problem is if you are rendering to a resolution that is different than your project. If you want everything to line up correctly, your render dimensions and aspect, and project dimensions and aspect must match exactly.
One of these or both are most likely your problem.
~jr
http://www.johnrofrano.com
http://www.vasst.com -
John,
thanks for the info regarding the MEG2 in this post. Interesting… I didn’t know only 1 out of every 15 frames is accurate. Good to know!
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https://www.davelozinski.com
https://www.davelozinski.com/DemoReel/
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[Dave Lozinski] “I didn’t know only 1 out of every 15 frames is accurate. Good to know!”
Yes. MPEG video is stored as a Group Of Pictures where one out of every 15 frames is a full frame. The other 14 frames are delta and predictive frames that only contain the information that has changed since the last full frame. This makes it difficult to track objects accurately.
~jr
http://www.johnrofrano.com
http://www.vasst.com
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