Improve High Frame Rate Handling

[thermidorthelobster]

I'm just imported a clip in HFR (shot at 100fps in a 50fps project). BRAW Toolbox imports it quite happily but the sync clip has the video playing at 50fps, so the video is double the length of the audio.

I'm not sure the ins and outs of how FCPX deals with HFR in sync clips, but to my mind it would make more sense if the sync clip had the original video retimed to double speed so it the video matches the audio duration, but with the option to then slow down the sync clip once it's edited onto a timeline without dropping frames.

Difficult to explain, but the logical way seems to be for the 100fps RAW clip to be conformed into a 50fps sync clip so that it plays normally, but if the sync clip's then slowed down by 50% you'd get the original 100fps shooting framerate back; or if FCP won't go looking for intermediate frames from a 50fps sync clip, for the sync clip to be 100fps so that it could be sped up once edited onto the timeline, or left at the normal speed, without losing frames. I know what I mean, but I'm struggling to communicate it!

[latenitefilms]

Are you able to share with me the BRAW clip by any chance?

You can upload here:

https://latenitefilms.digitalpigeon.com

I'll have a play and a think too about how best to handle it, and see what it looks like when you import the same BRAW file into DaVinci Resolve.

[thermidorthelobster]

On its way now. Please disregard the subject and quality, it’s not indicative of my normal canon of work :)

[latenitefilms]

I wonder if you can just slow down the audio by 50%, then create a new compound clip, then speed it up by 50%?

[thermidorthelobster]

I’ll try that; the only thing is, creating CCs in FCP only gives access to regular frame rates, whereas shooting HFR in BRAW can create odd frame rates such as 53fps. Does BRAW Toolbox have access to arbitrary frame rates when it sends the XML back to FCP?

[latenitefilms]

Correct me if I'm wrong, but my understanding is that Blackmagic cameras only support a project/base frame rate of 23.98, 24, 25, 29.97, 30, 50, 59.94 and 60 fps? However, the sensor frame rate can then be any number in-between? I believe you can only setup Final Cut Pro can only create projects and compound clips with these standard frame-rates.

Assuming that's the case, we'd keep the Synchronised Clip/Multicam Clip the same project/base frame rate, and then use a speed effect in Final Cut Pro to do the "adjustment".

My current though is that maybe if project/base frame rate doesn't match the sensor frame rate, then all we do is add a speed effect to the audio and trim accordingly. That way the Synchronised Clip/Multicam Clip that comes from BRAW Toolbox is always in the project/base frame rate, but plays at the sensor frame rate, with "stretched" audio. If you then want to play it back at "real time" you can just add a speed effect and adjust accordingly. It's also possible we could automate this with BRAW Toolbox, so that when you import HFR clips we import this stretched audio clip, along with a Compound Clip that automatically does the conversion?