Converting, importing and working with H265/120fps footage in Premier Pro

[philvideofilm]

Hi all,

Ok so here is the step by step workflow so far

1: Shoot the project with a Samsung NX1, which yielded H265 files

2: Because Premiere/Vegas (my two preferred NLE) I transcoded those files into H264 with the Rocky Mountain converter.

Now something weird is going on, Mediainfo tells me that the original file is in 60P, even though we shot it in 120fps. Once I converted the file and kept the 120 frame rate through the converter's options, Mediainfo tells me that the resulted file is still in 60P.

3: I import the footage in Premiere and it tells me that the file is in 60p

What am I missing here?

-If I try to slow down the footage to 15-25 percent of it's speed it looks quite good and it wouldn't if the footage was indeed in 60p

-If I try to "interpret" the footage and conform it 120fps Premiere shrinks the duration by two and playback speed is doubled.

Here are two files, the original and the converted one, if you want to take a look at them

https://www.dropbox.com/s/97958mqqiwip9mt/Original.MP4?dl=0

https://www.dropbox.com/s/5ucjrg405tghwvb/Recoded.mp4?dl=0


Thanks for your input on this matter.

Phil

[poisondeathray]

It looks about right. Some cameras flag the recording a different frame rate for slow motion and various speeds. What is important is the actual number of frames recorded - you can interpret the framerate in your editor

This looks like a 120FPS recording flagged at half speed - so it plays back at half speed when played back at 60FPS in a media player

For example , if you have 30 seconds of actual time, it would be represented by 3600 frames if recording at 120 fps (120*30). The recording is flagged at half that for 1/2 playback speed, so it would be 60 seconds duration. In your "original", mediainfo says it's 31sec767ms - so the actual physical time of the recording was actually half that - a bit over 15 seconds

So if you use a 60FPS timeline in your editor and drop this clip in (or rather a digital intermediate of it), it will playback at 0.5x realtime speed (by this I mean actual recording time speed) , which is what you want because that's what it is. You just interpret the rate to whatever your needs are, keeping in mind that at 60FPS you're at 1/2 realtime . Or another way would be to change it while you're encoding to the proper 120FPS, then it would be "normal" in terms of playback speed (and you would still interpret it in the editor)

Most displays in North America only run at 60Hz - so if you played back at 120 FPS, you would drop 1/2 the frames anyways when played back at full speed

[racer-x]

Agree with PDR. Here is your source converted at 120fps.

[philvideofilm]

Thank you for your time gents, I really appreciate it.

Still, let me try to get this straight:

1: Indeed this camera can shoot 120fps but when it does so it, so to speak, wraps the resulted file in a 60p container

2: This file will be playable in a media player but will be so at 60p, thus at half speed AND the actual duration of the shot is also half

3: If I want to take full advantage of the 120fps I will have to interpret the footage as so in Premiere Pro

Am I in the right ballpark here?

Thanks

[poisondeathray]

1: Indeed this camera can shoot 120fps but when it does so it, so to speak, wraps the resulted file in a 60p container

Basically yes. Out of the camera, it's already 1/2 speed

2: This file will be playable in a media player but will be so at 60p, thus at half speed AND the actual duration of the shot is also half

Duration of the clip is double, because speed is 1/2. The same number of frames are just played back at half speed.

e.g. a 15 second real time recording will now be played back as 30 seconds, because the speed is half (slow motion)

3: If I want to take full advantage of the 120fps I will have to interpret the footage as so in Premiere Pro

You interpret the footage to whatever you want. You keep in mind that you're starting with a 1/2 speed clip. If you import it as 60FPS, you can think of it as already interpreted as 60FPS from a 120FPS clip. Assigned frame rate is mostly irrelevant, it's the number of frames that are important.

The most common use of 120FPS is Slow motion. Interpreting footage in a NLE doesn't add/drop or blend frames, it just plays back the footage (the same number of frames) faster or slower. That's why the duration changes - it's supposed to.

If you're using this NOT for slow motion, and the destination frame rate goal is lower, then you need to drop frames. That's not the same thing as interpreting footage which keeps the same number of frames. For example, if you wanted 60p at 60p (real speed) , you would drop half the frames and keep it at 60 FPS. (There are other differences, such as motion blur, shutter speed that you would have to emulate to make it look more authentic, because 120FPS aquisition would have been at a faster shutter than say, 60p at 60p , or 24p at 24p)

You might already know this, but but be careful of how assets interact with the timeline. If you have different settings for the timeline, it will conform the asset to the timeline settings. If you have clip blend on, it will blend frames (same with in vegas, with smart resample enabled) . If you have it disabled, it will drop or add duplicate frames to achieve the timeline FPS. In general you want to make sure you keep everything in evenly divisible integer multiples.

[philvideofilm]

Well ultimately the final edit will be rendered out on 23.94fps, and about 75-85% of the shots will be in slow motion.

Now I did some test with another file and found three ways to make it last 6800 frames
-Interpret the footage at 23.984
-Keep it at 60p but slow it down to 40%
-Interpret the footage at 120fps and slow it down to 20%

Two points arise from those tests:

Which approach is better?

What's important for me is to see the actual speed of how things unfold in each shot so that I can be sure if I want to slowmo it or not.

Thanks,

Phil

[poisondeathray]

Well ultimately the final edit will be rendered out on 23.94fps, and about 75-85% of the shots will be in slow motion.

Now I did some test with another file and found three ways to make it last 6800 frames
-Interpret the footage at 23.984
-Keep it at 60p but slow it down to 40%
-Interpret the footage at 120fps and slow it down to 20%

Two points arise from those tests:

Which approach is better?

What's important for me is to see the actual speed of how things unfold in each shot so that I can be sure if I want to slowmo it or not.

Is that a typo? Did you really mean 23.976 (24000/1001) ? Because "23.94" is a non standard frame rate.

Neither is "better" . Your test is showing the same thing, produces the same results. It's just a ratio relationship, that's all. As mentioned earlier, the interpretation isn't really that important - it's the actual frames that are important. You have to get that straight in your mind, otherwise how you use the clips later on might cause problems

Different people will have their own preferences as to how to do it. HEVC is going to be supported in the next update for PP, but for some people it might be better to use an intermediate as 120FPS (or 119.88) to keep things more straightforward. You said you used some converter and it produced 60 FPS when you specified 120 FPS . I'm not familiar with that software , but it's probably doing something wrong.

Keep in mind, when you use a 23.976 timeline, that's all you see. 23.976 samples per second. If you drop a 120p clip on it at normal 1:1 speed - you won't see all 120 frames/s, you will only see approximately 1/5 of the frames (even though the others are still accessible for speed changes). It' s just sampling about 1/5 of them ie. showing you approx. every 5th frame. I say "approximately", because 120.0 isn't evenly divisible into 23.976. Which leads to the next point:

Also beware of 23.976 vs. 24.0 differences when using it for Non slow motion sections - When you use non integer multiple, the editor will make up the frames by dropping (or blending if you have frame blending on) . This will cause glitches in the cadence unless you've accounted for them. The 120 FPS should be interpreted as 119.88 if you're using 23.976 (23.976 * 5 = 119.88) . Same thing with "60p" which is usually 59.94, not 60.0 . This also raises possible sync and audio issues that you should be aware of depending on how you use it.

[philvideofilm]

Yes it was a typo, and yes I do know the precise frame rate, I just use 60 or 120 to type faster

No need to worry about sync as there is no sound.

Well I guess, for this project, it boils down to the fact that I need to see things at their original speed if I want to make a proper edit. Problem is that if I interpret the footage all my "in" and "out" points will be messed up and I will have to start all over again.

Thanks for all your help, I really appreciate it.

[poisondeathray]

Well I guess, for this project, it boils down to the fact that I need to see things at their original speed if I want to make a proper edit. Problem is that if I interpret the footage all my "in" and "out" points will be messed up and I will have to start all over again.

I'm not sure if I'm understanding you correctly, but it's not a problem. You just make multiple instances or copies of clips in the project media clip bin. Each one can have a different FPS interpretation. (e.g. you might have a 120fps "normal speed" version, a 1/2 speed 60fps version, a 1/5 speed 24fps version, etc... They are not "physical" clips - they all reference the same "original". Make sure you get in good habit of renaming them and/or organization in folders - it will help with larger projects . If you need speed ramping (gradual changes over time), you will have more control in AE

[racer-x]

What I don't get is, why are you converting your hevc footage to a very lossy AVC format? I'm assuming this is production work? Why not use a lossless codec or at the very least a high quality lossy codec like CineForm, ProRes or Grass Valley HQX?

You can use Virtualdub via the latest ffmpeg input drive to load your hevc and export to any compression codec you have installed. That's what I used for the conversion I posted earlier...

Fortunately I have the means to edit hevc natively. I like the look of the Samsung NX1 footage, unfortunately I already have a lot invested in Canon lenses, otherwise I would consider buying one of these.

[poisondeathray]

I'm not sure how you have your project organized, but you can use time remapping to do the speed changes as well. The next update of PP will have optical flow, so it's going to be less important to go to AE for speed changes. I'm not so sure HEVC decoding will be very smooth in PP however...

The way I would do it is plan for the least amount of work. If most of the footage is supposed to be slow motion, that what I would have them interpreted it as. It's more work to manually interpret or modify clips than to import them at the rate they are going to be used at

+1 on racer-x's comments on using lower quality intermediates. At minimum, use a higher bitrate or I-frame only

[philvideofilm]

That's ok because I just finished trimming and didn't edit per say, I will just restart the trimming and organize it by bins for different speeds.

The converter I used offers to encode in ProRes but the files were HUMONGOUS!!!...I am ok with the lossy conversion because I love the quality already and the final output will be Vimeo at 720p

[poisondeathray]

Plan it ahead of time, if not for this project at least for future projects. If you are using slow motion - by definition it will extend the timeline (duration) by adding extra frames for those slow motion sections. So if you already had timed edits in place (especially with audio), it's going to be a problem. If you're using the same clip for normal speed and slow motion, then it might be a better way to use the time remapping method. You just adjust it "on the fly".