Trancoded prog. 59.94fps files to 30p "shutters"

indyman777 wrote on 1/5/2011, 1:55 PM
I've been trying for days to figure this one out... I have a bunch of video files filmed at 59.94 fps (progressive). They are a resolution of 1920x1080. I first run default stabilization on them to smooth out the camera's deficiency. When I transcode the files to 30p, they seem to "shutter", for lack of a better term. It's not a playback issue as both computers I've tried them on are extremely fast (4 to 6 processors with high-power CUDA video cards). It looks similar to a video displayed at a low frame-rate.

I disable resampling to eliminate "blending" that appears on the frames, since the 10-second clip I'm using for testing has some motion panning in it. Other than that, everything seems to be set at their defaults. It doesn't seem to make a difference what I set the project frame rates to, 29.97 or 59.94.

If I transcode them to 60i, they look good...nice and smooth. What am I missing? Any advice would be appreciated!

Comments

Eugenia wrote on 1/5/2011, 2:57 PM
Try the same exporting, but without the stabilization process. If it doesn't happen on a plain 30p without stabilization, then it's a Vegas bug of stabilization of high frame rate sources. Sony might have been optimizing their stabilization algorithm for 24p or 30p and forgetting 50p/60p. In that case, you would have to make a formal bug report and wait for a fix. Or, get a tripod. :-)
indyman777 wrote on 1/6/2011, 8:38 AM
Good idea! However, same results.

One thing I notice is that when it renders to 30fps , the preview screen shows the frame count going up. However, as the count increases, it shows the same frame for three frame counts. Is that normal, or should it show every frame as it is being rendered?

I'm really at a loss on this one.
indyman777 wrote on 1/6/2011, 8:49 AM
So, I tried something out. I took the transcoded clip that shutters and dropped it into the timeline. Then, I step through each frame, one by one. Sure enough, every two frames are identical. What would be causing that?

I verified that the source file has unique frames.
magillagorilla wrote on 1/6/2011, 9:31 AM
Sounds like some kind of weird pulldown issue like 2:2 (but that would be a PAL 24p to 25i) . Are you sure all your sources are progressive and that your target render is progressive? It just seems like the software is trying to do a frame rate compensation for what every reason.
indyman777 wrote on 1/6/2011, 10:14 AM
First, thanks to everyone who is trying to help me. I didn't expect quick responses to my post.

The source file is progressive, and the target render is progressive as well. The project is set as progressive. The camera was panning, so there is motion.

I've saved the file as both a 30p progressive file and as a 60i interlaced file using the Sony AVC option (both mpeg-4). Both files end up being just about 25MB in size, within .5MB of each other. The 60i has MUCH less jitter. Do you think it could be an issue with motion being displayed interlaced versus progressive?

UPDATE: The more I look at it, the more it appears that all frames are being transcoded in to the new file (all frames are unique). I think what I was earlier looking at an older test file when I said that every other frame was unique.

Do you think it could have more to do with how the file is displayed on my LCD (maybe how the codec handles it)? When I compare each frame side-by-side and frame-by-frame, they look pretty identical.
magillagorilla wrote on 1/7/2011, 12:16 PM
What is your target output? Why are you throwing away half of your frames? What camera are you using to get 1080p 59.94fps?

Also, I think you know this, but make sure when you transcode you choose 29.97fps and not 30fps for your 59.94fps footage.

I would definately suspect the monitor. Stuff like refresh rate and pixel speed have a lot to do with shutter. Can you hook you PC up to a good HDTV? If you have a BR burner can you burn a sample to BR and play it on your good TV?

Progressive 30fps and 24fps can look a bit shuttery no matter what you do. Interlace will smooth out your temporal motion but can degrade your frame resolution.

The best option is to keep it 59.94fps progressive unless: Your camera only allocates 17mbps (for instance) to 30fps or 60fps. In this case the camera allocates more bits(quality) per frame at the lower frame rate. But if "smooth action" is what you are after then stick with 60i.

As a videographer know your scene when you are shooting. A kids soccer game; go with highest frame rate, ducks on a pond; go with highest resolution. (sorry if you are already fimiliar with this).

Just wondering why you would shoot at such a high frame rate only to cut it in half. And computer monitors come in a wide variety of quality. Mine is cheep and does not have fast pixels (this ghosting). Many monitors are built to display a web page or email and therefore cannot handle fast motion.
indyman777 wrote on 1/11/2011, 7:45 AM
My target output is 29.97. I wanted to reduce the number of frames to conserve space while keeping an acceptable frame-rate. The video was shot with a Sony Xacti VPC-FH1a.

I wouldn't mind keeping it at 59.94fps. However, I cannot seem to save it in that format. Every time I try it with Movie Studio, it gives me an error, no matter on which computer I try it. I don't see that they even have a default setting for that mode. The only way try to do it is to manually change the settings, but then it throws up an unspecified error message at when the transcoding begins. Have you been successful transcoding it to 59.95fps progressive?

It would seem to me that the monitor should display at 30 fps progressive. It's only two years old at the most. I remember considering the speed rating when purchasing it. However, I do have an LCD television connected to a HTPC. I'll try putting it onto a thumb drive and try to play it on that screen.

I originally noticed that the video seemed quite juttery when recording at 30fps, so I recorded the next batch of videos at 60fps (I'm using round numbers, here), hoping that it would help. I had hoped that by running software stabilization on a higher fps source, I would get even better results that could be transcoded down. Maybe keeping it at 60fps is what I'll have to do, if I can ever figure out how to make Movie Studio do it.