7D Problem with slow motion from 7D (Converting 60p to 24p)

Hawk Teflon

Hawk Teflon

Veteran
We recently shot some footage with the 7D at 60p. We did this to put into our 24p timeline at a slower speed. We pushed the shutter from 50 to 125 for those shots. I ingested the footage using FCP Log & Transfer. From there I opened Cinema Tools, and converted the footage to 23.98. Unfortunately, it now looks stuttery. Here is a clip of what I'm talking about (it's no compressed, so it's about 80MB):

http://www.mediafire.com/?kc0kh0i48072g6r

This is the same process I've used on my T2i, and there was no problem. I CANNOT confirm my shutter speed on the T2i footage, though. Is that the wrench in the machine?
 
I'd guess the stuttering is more due to compression than to frame rate issues. Try doing an export to ProRes Proxy from QT player of that shot and see how smoothly it plays.

Noah
 
Hi Hawk, I have seen this and run into this exact problem and I have not found a solution. Here are some 'clues' or 'observations' that I have noticed
in your footage as well as in my own on various projects

1. The stutter is always related to a panning shot.
2. The stutter occurs at different points on the timeline during playback for each time you play.
3. The stutter occurs randomly and has nothing to do with shutter angle (although this can soften the effect)
4. The stutter can be lessened by dropping the bitrate.
5. The stutter effect can be stronger or lesser depending on the combination of codec vs. bitrate. vs player
for example try dropping the bitrate to 2mbps in h264, in mp4 container and playback with vlc and you are fine

The first time I saw a lengthy thread on this topic was RU
http://reduser.net/forum/showthread.php?28219-Stuttering-image-while-Panning&
 
Thanks for that link. I spent a good portion of this morning reading through that. I guess it's good to know I'm not the only one, but it still doesn't ease my pains. I'm going to do some testing in the coming days I think.
 
Hello Hawk,

I have the same issues with the 7d, but it is not exclusive to this camera. The 5D has it, i just seem to notice it in my own vids more than in others. I had to look at your footage twice to notice it.

I have been trying to do a smooth pan with the 7d, but that seems nearly impossible. you have to go extremely slow and speed it up in post. (not always feasible).

It is not as noticeable in shots with shallow DOF, or when the camera is following a subject.

If you look for the stuttering you will se it in all videos shot with the dslr's. In fact it shows up in live view as you do your pan or dolly. All CMOS cameras seem to suffer from this.

Adding motion blur helps a little but that defats the purpose of wanting to do a slow pan or doly shot.

Very annoying but a lot of people do not even seem to notice it?
 
Have you tried putting the 60p footage in a 24p comp in AE or Premiere? If your system can't handle the original files, you can use Mpeg Streamclip to transcode them to dnxhd. Just be sure to access the drop-down list of frame rates and sizes by clicking on the mostly obscured arrow in order to maintain 60p.
 
I've tried in AE, but even with time remapping and time warp I can't get anything like I feel I should (though I didn't plan to use TW, so my shutter simply wasn't high enough for that). It's been many many moons since I've used Pr, but I'm willing to give that a try.
 
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Just an update, I feel a lot of this might have ALSO been resolved had I turned the IS off on the camera.:crybaby:
 
I don't know if you are still looking for an explanation but I recently did a lot of slow motion on a short I shot, this is what i did and it worked very nicely. First shoot your footage at 60 with the proper shutter speed. Then re compress it to pro res with the same frame rate. Now you have your footage ready to edit, this is where I think you went wrong. What you did was drop 60fps footage into a 24 fps timeline, essentially making it play in 24 which negates you shooting it in 60. What you need to do is this, make a new sequence. Drag the 60fps clip into the time line so it will now ask you, do you want to change the sequence setting to match the clip? Click yes.... Now you have a properly formatted timeline for the 60fps clip. Now you have to do some math to make the clip slow motion and 24, the equation calls for the clip to be slowed to 40 percent the speed and turn off frame blending. Now export this clip as a quicktime movie, THEN import into your 24fps timeline. Perfect slow motion.

i did do this from memory, I am at work if there is a problem message me and ill try to figure it out. This should work though??
 
So what would be the plus side of that as opposed to putting it into Cinema Tools to conform to 23.98? That's the route I followed. I didn't insert 60p into a 24p timeline.
 
From what I understand what your doing is just re compressing the footage back into 24. I can't really wrap my brain around why I think it is different, but I think my way takes the clip and compresses it into 24 without dropping the frames. Your way I believe, is dropping the frames and keeping the clip the same length. Give my method a shot, it worked nicely for me and I got some pretty fluid slow mo. Obviously not as smooth as the phantom but pretty fluid.
 
Since I'm waiting on transcoding anyway, I'll give your method a shot.

However, Cinema Tools won't keep the footage the same length with drop frames. It extends the footage 250%. So a 1 second 60p clip will now be 2.5 seconds of slowed down footage at 24p.
 
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