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24p footage slowed down in Vegas becomes interlaced in render
Hi guys,
I shot a video in 24p, which is true 24fps progressive on a Canon Vixia HF S21. I’ve done several videos like this and the footage comes out fine.
I slowed down some footage on my timeline and it looks fine when I’m previewing it. I’ve got all my properties of the video set to what it was in camera, so progressive, 23.976 fps, and same high definition resolution. I used a shutter speed of 1/48th.
But when I render to mp4 at 23.976 fps, progressive, or wmv at the same settings, the slow motion footage shows a lot of ghost frames, as if the video has been interlaced.
What’s going on? I right clicked the clips and went to the properties to make sure nothing changed, and it all looks fine-23.976 fps and progressive scan.
Also, a larger part of the video is footage from the same shoot in real time and it plays fun, so I’m sure slowing down the footage is doing it somehow, but I can’t find anything that would make ghost frames show up and interlace the footage when nothing about my camera or the project settings should be making extra fields. Again, in the preview monitor it’s fine, but even though I’m using the same settings to render the progressive footage that I always do, only the slow motion footage has bad interlacing.
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4 Replies
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I’m getting one more weird problem. I’m using the cookie cutter and pixelate plugins along with keyframes to pixelate someone’s face. I went through three clips to do it, and in each one it worked fine except when I went back to the video and increased the amount of pixelation to make the face more indistinguishable. The rendered video never shows the new change. I adjusted the cookie cutter keyframes to stay over the person’s face better and it renders all those.
I tried rendering in mp4, wmv, and rendering to a new track, but it’s all the same, though in my preview monitor it plays fine. I tried closing and restarting Vegas and still have the same problem. I also tried moving the clips to a different track on the timeline in case it was a setting on the timeline, but it still doesn’t render the changes.
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[Angelo Mike] “the slow motion footage shows a lot of ghost frames, as if the video has been interlaced.”
Don’t confuse ghosting with interlace artifacts. The ghost frames are caused by you slowing down the footage. The footage still plays back at 24fps. If you tell Vegas to slow down to 20fps, then 4 frames must be synthesized out of “thin-air”. The way this happens is two frames get blended together to form a third. This is the ghosting you see.
The only way to avoid it is to use a better plug-in for slow motion like BCC Optical Flow or Twixtor, which are smarter about synthesizing the new frames. Otherwise you should not try and slow down 24p footage. You really need to shoot those scenes at a higher frame rate and then slow it down to 24p.
~jr
http://www.johnrofrano.com
http://www.vasst.com -
Oh. Thanks. Is Twixtor available for Vegas 9? I’ve read that it’s only available for Vegas 10.
By the way, the pixelation problem sorted itself out, basically. What I realized is that even though the changes I made to pixelation look bigger in the preview monitor, it doesn’t look as dramatic a change in the finished video, so I had to bring the pixelation way up to make a noticeable difference.
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[Angelo Mike] ” Is Twixtor available for Vegas 9? I’ve read that it’s only available for Vegas 10.”
I believe it’s only available for Vegas Pro 10 as is BCC Optical Flow. You need to keep your software current in order to use the latest plug-ins.
~jr
http://www.johnrofrano.com
http://www.vasst.com
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