Frame Rate problem - Can Avid solve it?

J

jjethree

New member
So I was just handed about 1.5hrs of footage shot on the HVX. I brought it into my Avid Xpress system and it is saying that is is 720p/60. It was shot with the conventional film thinking that you shoot at 60 and playback at 24 for slow/smooth motion.

However, you probably know where this is going, the Avid will not let me playback the footage in a 23.976 project. My guess (I'm an editor not a DP) is that the footage should have been set at 24pn with the vfr done in the camera. I can obviously cut this in a 720p 59.94 project, but it will be playing back in realtime. After hours of research, it seems like my only option might be exporting to sorenson and compressing all the media. Or (gasp) moving to Final Cut? Is there anything that I might be missing?

(According to an Avid document at:

http://www.avid.com/resources/whitepapers/Q2_06_hdcameras.pdf

"Footage recorded at 720p 60 on the camera and played back in the 720p 23.976 Avid Project will result in a smooth 2.5x slow motion effect.")

Any help would be greatly appreciated. I need to find a solution asap.

John
 
Yeah, you've hit the nail on the head. Avid makes no provision for working with offspeed media in a 720p/59.94p project. As you surmised, if the footage had been shot in 720p/24pN mode with an overcrank of 60fps, then yes, you could bring the footage into an Avid 720p/23.976p project, and it would plays not back with the 2.5x slower effect that you expect. However, there is no frame rate converter as there is in FCP.

There might be a solution, though, albeit not the most elegant one. What sort of project are you cutting this project in? 23.976? 59.94? Because...

If you're cutting it in a 59.94p (60p) project, and you want the 2.5x slower speed, just apply a 40% motion effect. It will duplicate and pad out frames to create the speed you want (I'm assuming the footage was shot with a 24p timebase in mind, with a VFR of 60, so 24/60=.4=40%). This is basically how the Varicam works (always shooting in 60p), and how the HVX works when shooting in non-native 720p/24p mode (which is what I'm assuming was used to shoot this footage). You're not going to get interlacing artifacts or anything like that, as you're working a progressive project anyway. You're essentially inserting 2:3 pulldown to pad the media out to play back at 24fps with the slow motion effect.

If, however, you're cutting the project in a 720p/23.976 project, you would follow all these steps above with the 40% slowdown, and then do the following:

1) Export your clip/timeline with the slowed down clips to a Quicktime reference. Use the "same as source" settings, blahblahblah.

2) Open up your 23.976p project, and import the QT reference clips. The Avid will strip out all those duplicate frames that were added in the 59.94p project, but the slow motion will still intact and you'll now have true 24fps media. You can step through the footage frame by frame, and you'll see that each frame is discrete from the previous and the next.

Hope that makes sense, and again, I'm making a couple of assumptions here based on what I gleaned from your post. Reply if you need any other info.

Good luck!
 
Thanks cbrougham & DC, my concern with the method you suggest is - will the quality be affected? I was hoping that the Avid/AE wouldn't have to create extra frames. Rather I want to use the exact amount of frames - but available in a 24p project. I will test out your method as well as conforming the frame rate in AE and rendering there to see which is faster and produces better looking results.

My question now is... given that the footage was shot 59.94. Would Final Cut be able to play this back at 24.976 in real time? Or would I be in the same boat - rendering the footage with the built in Frame Rate Converter.

I guess Avid's statement above is deceiving - the footage needs to be recorded at 24pn in order to play in a 23.976 project. Hopefully they will be adressing this soon or there will be an aftermarket program that can handle this efficiently.

Every MXF / P2 project I have worked on has been a struggle. Avid and Panansonic need to develop a rock solid workflow. A workflow that doesn't involve consolidating or transcoding. A workflow that allows a project to easily be rebuilt in the future. And a workflow that allows for the open timeline that Avid has been boasting about for years. Phew, rant over - I had to get that off my chest.

I just want to edit...

John

PS A workflow that provides a fast and efficient backup of the media (ON SET) so that the production company can have a "hard copy" to put on the shelf - immediately. That would be nice too.
 
Ran the tests and found that the AE render results were much better. The avid motion effect(ed) version had a noticeable strobing where the After Effects render was very smooth and rendered faster. It is possible that AE is just altering the timebase vs. Avid doubling the frames.

Here is the method I found. Load footage to 59.94 project. Export Quicktime Reference movies. Import into After Effects. Interpret Footage / Conform to Frame Rate / 24.976. Create Compostion. Render to DNxHD 90 Codec. Fast Import to 720p 23.976 project.

Still waiting to hear if Final Cut Pro can do this in realtime?? Anyone?
 
Avid can take the 720p/59.94 as a signal based capture and play it back as 23.97 for a 2.5x slomo. When using the HVX200, the camera needs to be in the 720p/24pN mode and then set it to cinema and frame rate of 59.94fps. This will record all 59.94 frames with the intent of being edited and played back at 23.976 - resulting again in that 2.5x slomo.


Michael
 
jjethree said:
Still waiting to hear if Final Cut Pro can do this in realtime?? Anyone?
Click to expand...

Haven't used it, but my understanding is that the Frame Rate Converter in FCP can be used to do exactly what you're suggesting. Basically, you'd open your 60fps footage in a 23.976p (24p) project, run the FRC, and it would conform the 60fps media to the 24p timeline--giving you the 2.5x slow-down. We're talking about using 720p/24p (ie. "over 60") footage here--not 720p/24pN footage.

Avid works great with native 720p media in a 23.976 project--but the problem comes in when using something like the Firestore FS-100 in order to record offspeed media. At present, the Firestore doesn't record offspeed in the new native modes--only in "over 60" mode. As such, you can't use offspeed clips recorded this way easily in the Avid. Ideally, you'd only record offspeed effects to a P2 card, where you can record VFR in native mode--but I know that I'm not always in a situation where I can easily deal with the limited times offered by P2 cards--I'd much rather use the longer times of the FS-100 and its ability to record VFR.
 
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