Convert AJ-HDC27 Speed Ramp HDSDI Footage?

[Michael Krumlauf]

Major brownie points to whoever helps me with this one...

So as most of you know, the varicams are able to speed ramp in camera. I'm using a Varicam with an Atomos Samurai Blade recorder so i am bypassing tape. I am doing some tests to see if i can take advantage of speed ramping in camera, the only problem is how do i convert the prores file so it can playback the speed changes in real time? I've tried using Handbrake, Apple Compressor but no luck. Anyone able to help me on this one?

Thanks,

Mike

[Christopher Young]

The big question here is whether the "flagged" frames are detectable in the SDI feed from the camera to the Atomos in the ProRes capture. I never tried it but I would think not. The Varicams always recorded at 59.94p regardless of what frame rate the camera was set at. Although all the time code was 30 fps based regardless of VFR setting. With the Avid systems there was a "on or off" mode as to whether the system would capture the footage at 60p or capture just the flagged frames that represented the VFR rate that had been set on the camera at time of shooting. I can't recall the VTR models now but there were some specific Panasonic decks that with frame rate converters attached could detect the VFR flagged frames and play them back at the VFR recorded speed.

From an Avid paper from way back when:

"Using Variable Frame Rate (VFR) is very straightforward. The 720p format is always recording to a progressive 60 (59.94) frame tape format. The different frame rates are achieved by selecting the desired frame rate and the camera flags the "true" frames within the 60 frame sequence. When these flags are detected by the Avid editing systems, only those frames are captured and stored to disk. When played back at the project’s frame rate, either a slow motion or fast motion will result.

There is a "Preserve Varicam Frames" check box in the Capture Tool Interface. If turned off (the default state of the button), the capture will observe the flags in the video stream and only capture those frames. This type of capture will result in a slow motion or fast motion depending on original recording speed. If it is turned on, then every frame is captured (all 60 frames), essentially ignoring the flagged frames."

I recall we had numerous dramas with this around 2001 and at that time we were using Discreet Logic's Edit* systems that could not detect the flagged frames. What we had to do was grab a deck from Panasonic that could play back at the flagged VFR rate and capture from that. After that we just did our VFR in post.

The only way I have been able to capture VFR footage on the Atomos recorders has been when shooting VFR on the Sony cameras that have VFR modes and triggering the recording from the Atomos touch screen. For example on the FS700 when you are in VFR mode the signal you can record to the Atomos is at a normal 25/30 fps output while the camera is in "Preparing" mode. If you are running 'end trigger' when you hit the stop button the FS700 then starts to dump from cache the VFR footage at the pre-designated VFR speed and you see the VFR footage playing out in slo-mo and the Atomos records it beautifully. Same with the CD's Nanoflash.

If the flagged frames are identifiable in the ProRes recording you would then need NLE software that can capture just the flagged frames. And I mean capture as opposed to import because this detection in the Avid systems was by capturing the DVCPro HD information as an HD data stream via 'Firewire.'

Let us know how you go. Good luck!

Chris Young
CYV Productions
Sydney

[Michael Krumlauf]

It seems that the only way I can view the ramp in real time is by doing the flagging myself in post which seems fairly tedious. Maybe other high end SDI recorders besides the Atomos can do this with better luck.

[Michael Krumlauf]

After many months of trying to figure this out, I finally did and am very excited. I've always enjoyed the way speed ramping looks when done in camera and was told by multiple people that the varicams allow this, i figure out how to ramp months ago, but it took me forever to figure out how to get the KiPro to accept the ramp. I dont know how many of you this will help, but given my excitement, I thought I should share the steps incase someone out there was trying to do it. Better to have info like this sitting on the net so people like myself are not spending hours googling it.

First and foremost, I have used two external recorders with my varicam, the atomos Ninja Blade and the KiPro Mini. Its important you use a recorder that picks up the flagged frames in the SDI signal, the atomos does not do this but the KiPro Does.

1. Set the KiPro Mini to VFR mode and make sure its Timecode settings are set to read the varicam's timecode or else it wont pick up the 24p signal.
2. Always have your starting frame rate be 24. The KiPro must begin with the 24 signal to lock itself into a mode where it will always flag unneeded frames.
3. Once its recording, hit the JOG dial so the frame rate is flashing and then use the syncro scan buttons to toggle through the frame rates and preform your ramp.
4. Make sure you go back to 24 before you stop record. Once you play back the footage you will see not only do you have a 24p clip, but if you change frame rates it will slow down or speed up without any post work being done.

If you want a quick ramp, set the User 1 or 2 button to whatever frame rate you want to ramp to and once you run the camera (remember always begin at 24) and hit the user button it will jump right to the frame rate you set.

This is a very powerful feature and made me fall in love with my varicam all over again.