Jittery Slow Mo?

[gvsuk]

Hi Guys, sorry if this has been covered but I cant get my head around this?

I have Sony A630 and am now trying out the HFR side of recording. I have it set to record 1920x1080 100fps, 200 shutter speed, 60mbs.

I can record and play back fine in Premiere on my 25p timeline in real time.

However, when I change speed of clip to say.... 50% or 25% it becomes very jittery and no smooth slowmo?

Can you please tell me where I am going wrong?

Thanks guys.

Alan

[DavidTeubner]

Try right-clicking the video on your timeline, and then select Time Interpulation > Optical Flow. Render it out. It should smooth out. Also, I made a video about this: How to fix 4k jidders/stutters using Premiere's Optical Flow - YouTube

[James_eater · Accepted solution]

You have to interpret your footage into the correct frame rate. If you don't and say drag a 120fps file into a 25p sequence and just ramp down the speed, all you're telling Premiere is how fast your want that footage to play in a 25p sequence not that the footage is actually slower.

- Select all your HFR clips in your project
- Right click > Modify > Interpret Footage
- Select "Assume this Frame Rate:" in the top menu section
- Enter the frame rate of your sequence, 23.976/25/30
- Click OK

Now when you drag your clip into your 25p sequence it will be buttery "slow motion".

[excited_Genie16B8]

Search the PDF for "Interpret"

https://helpx.adobe.com/pdf/premiere_pro_reference.pdf

[gvsuk]

Thanks guys really helpful.

So basically I can just record everything in 100fps and only need interpret when I need SloMo?

Thanks

[James_eater]

It depends on what look you're going for. If you do not interpret the footage and just drop it in your 25p sequence, it will look "hyper real". Meaning it will have a very odd "video" look (think soap operas).

What you need to do is interpret your 100fps footage to 25p. Put that in your sequence, and then speed it up by 400%. This will bring the footage up to "normal" speed and also keep a filmic look.

[gvsuk]

Thanks James,

Yes I understand what you are telling me but can I assume that audio would be ok? Apart from when I use slow mo obviously.

Up to now I have been using only video camera's with standard 1920x1080 25fps so I am venturing into the HFR world and not quite understanding how it all works. I am assuming that I can just record in HFR 100fps at all times?  I now also have a Sony FS5 with HFR upgrade and am hoping to maybe record everything in 100 fps and just interpret for slow mo when required. I do appreciate you guys helping here.

Thanks Alan

[James_eater]

You can always just pull the audio track from the uninterpeted footage. But in general I personally capture audio in a separate device when shooting HFR

As for shooting HFR all the time, you certainly could. And it’s woulf be a creative choice for sure. But you may want to do research on how frame rate and shutter speed effects how the camera captures a moving image and how light can be effected.

Another thing to consider is how HFR impacts the camera. You’ll be eating through batteries and storage, and some cameras don’t sample from the full sensor when in HFR mode and limit your ISO leading to noise

[gvsuk]

Thanks James, really helpful

Alan