Off Speed

Hello,

First time shooting with BMPCC6K yesterday. I want all my footage to be slow motion at 50fps. I was unfamiliar with the Off-Speed Recording function. I set the Project Frame to 50fps, but it seems the off-speed recording was on and set to 25fps. Luckily, I noticed a few shots in (I saw on the display in the top corner: 25/50fps and changed to 50/50fps. I was too nervous to turn off the off-speed entirely at that point as I didn't know what it was).

I'm editing in FCPX. All of my shots that were in 50/50 are perfect - they play back at 25 and I slow them down 50%. The first few shots that were 25/50fps seem to play back at quadruple speed. When I slow them to 50% - they are playing at 25fps. I have tried on a timeline set to 25 as well as a timeline set to 50 and it seems the same. The info on the clips say they are 50fps which is odd. Just wondering if there is a way to fix this? A few people have suggested getting the footage into Resolve but I've never worked with resolve so kind of looking for a FCPX option.

Thoughts?

Not sure you fully understand how frame rates are set on Blackmagic cameras. Just in case there’s some confusion, let me quickly summarize:

The Project Frame rate is the frame rate that your video uses to playback video. Normally that might be 25 fps or could be 50 fps if you want that. This is typically also the frame rate of your timeline in your NLE.

The off-speed frame rate is controlled in two ways. You can define a rate that you wish to use which is slower or faster than the project frame rate, but it’s not actively controlling frame rate until you change the setting to turn off-speed On.

For example: you normally might set project frame rate to 25 fps and off-speed to 50 fps but have off-speed turned Off. In that scenario, you record a playback at 25 fps and motion looks real.

If you want something to playback in slow motion at half speed, you would set the project at 25 fps and turn On off-speed recording set to 50 fps.

If you want something to playback with faster motion then you set the off-speed lower than your project frame rate such as at 12 fps.

If you want more extreme slow motion, set the off-speed frame rate to much higher values such as 100 fps with a project frame rate of 25 fps for playback.

Some manufacturers will not record audio in camera if you are using off-speed recording. BMD cameras will record audio using the project frame rate so it won’t match the off-speed frame rate. In situations where off-speed is used the final deliverable audio is often from another source, not the camera audio tracks.

Thank you this all makes a lot more sense.

Having never seen the off-speed recording function, I didn't even take note of it until I was a few shots in. What I did was set the project frame rate to 50fps and the off-speed was ON and set to 25fps. When I noticed the error, I changed the off-speed rate to 50fps.

What I'm dealing with now: all of the clips that were shot at 50/50 are perfect. I put them in my timeline and slow them down 50% and they play in slow motion. The clips that were shot at 50/25 however are playing back very fast and when I put them on the timeline and reduce speed to 50%, they are playing back at what appears to be a normal speed (25fps).

What I would like to do is have all of these clips in slow motion. If I try to drop the speed down less than 50%, they obviously drop frames. It's just odd that all of these clips are still identified at 50fps when I check the clip info ... so I'm just hoping the info is there and there is someway to get them playing back at 50fps.

With the off-speed set On at 25 fps, you’re not going to see those frames in slow motion unless you interpolate frames in the software to insert a calculated frame between each recorded frame (optical flow). I’m not using FCP X to know if that is an option for you.

Cheers Rick. Is this something that is possible in Resolve? I've just downloaded it so I'm going to have a play now and see if I can sort it.

Take a look at Optical Flow in Resolve.

Take a look at Optical Flow in Resolve.

Since he's using Final Cut anyway, worth noting that it also has optical flow.

That was a really clear, succinct explanation of "off speed".

Take a look at Optical Flow in Resolve.

Since he's using Final Cut anyway, worth noting that it also has optical flow.

That was a really clear, succinct explanation of "off speed".

Thanks for filling in my lack of knowledge on FCP X!

I had off-speed turned on and shot in 24fps with 50fps playback. Would optical flow work to playback the 50fps at 24fps? The audio is for 24fps so it's killing me. Didn't mean to have slo mo. Any fixes for it for Resolve or Premiere would be great. Thanks.

Some manufacturers will not record audio in camera if you are using off-speed recording. BMD cameras will record audio using the project frame rate so it won’t match the off-speed frame rate. In situations where off-speed is used the final deliverable audio is often from another source, not the camera audio tracks.

I accidentally recorded in OSFR and I'm missing 1/2 my audio. when you say final deliverable audio is from another source... what do you mean by that?

the goal obviously is recovering the missing audio, more so, the "missing" audio, assuming it is indeed that.

I accidentally recorded in OSFR and I'm missing 1/2 my audio. when you say final deliverable audio is from another source... what do you mean by that?

the goal obviously is recovering the missing audio, more so, the "missing" audio, assuming it is indeed that.

Apologies for the lack of clarity. If I had the camera, for example, set to a project frame rate of 30 fps, but wanted to record offspeed at 60 fps, one method might be to record the audio on an external recorder at 60 fps and see if that matches the length of the offspeed video when playback is 30 fps.

I’ve never tried this though to see if it works. Are you able to test this? If I tried it, I would include Timecode on the video and the external audio to see if that helps. Unfortunately at this time I have a couple of rush projects to complete so I need to keep my nose to the grindstone.

Audio will never be fully in sync with off-speed (aka HFR) recordings. For short takes, it should work.
But people have been bitten even when recording at the project frame rate, using HFR.

Audio will never be fully in sync with off-speed (aka HFR) recordings. For short takes, it should work.
But people have been bitten even when recording at the project frame rate, using HFR.

This is what I'm coming to find.

I'm looking for a way to permanently disable this feature as it creates way more havoc than it's worth. Doesn't even seem to provide any benefit when filming anyway. I'm just beside myself because I never use it yet somehow it was on before I recorded an event so I did something wrong somewhere and I don't even know where hence wanting to perm disable. I will get with someone on the blackmagic team to talk about that.

Thanks for trying guys.

If you own one of those cameras where it's too easy to touch, just tape some hard sheet of plastic over it.
Seriously.
It has its uses if you want to play an intentional off-speed recording back immediately in the camera to show to the team. Other than that, it's dangerous and the same effects can be realised in post.