How to set the playback framerate to 24fps for a 240fps video?

polarapfel wrote on 1/2/2018, 6:42 PM

Hi there,

I am new to Movie Edit Pro.

Here's what I am trying to do:

I created a new project in Movie Edit Pro and set it to FullHD and 24fps in the movie settings.

I imported a single clip recorded with an iPhone 8 Plus, using the native iOS camera app, recording 240fps slow motion in Full HD.

I want it to play back in whatever play back speed it plays back on the iPhone. Imported in Movie Edit Pro, it plays back at 240fps.

How do I correctly set it to play back at the slow motion speed, assuming that's 24fps?

I tried using the speed effect under "Effects", setting it to 24fps manually, but the playback quality is so bad and choppy, not at all comparable to how smooth it plays back slowly on the iPhone itself.

Any advice how to deal with that?

thanks,

Tobias

Comments

RogerGunkel wrote on 1/3/2018, 4:50 AM

Hi Polarapfel,

It's impossible to answer your question without you first giving some information on your editing system.

What version of MEP are you using, is it up to date, what is your editing computer spec, is it a Mac or a PC? What processor and graphics, how much Ram memory, what O.S. are you working on? All of these things are relevant to the performance.

Roger

johnebaker wrote on 1/3/2018, 6:05 AM

Hi and welcome to the forum.

. . . . I want it to play back in whatever play back speed it plays back on the iPhone. Imported in Movie Edit Pro, it plays back at 240fps. . . . .

This is an issue with iPhone slo mo video - quoting from Apple support - 'Slo-mo movies don't include speed variations in Windows. The speed they play depends on the app you view them in' and presumably import into as well.

Use MediaInfo to analyse a slo mo clip from the iPhone and post the results from the Tree view in MediaInfo.

When you imported the clip into MEP which option did you click when this message appeared?

Please read this topic and put this information in your profile signature so we do not have to keep asking for it:

Computer specification - processor make/model, graphics card or chipset make/model, audio card or chipset make/model, RAM, hard drive configuration, sizes and free space?
Windows version and is it up to date? Press and hold down the Windows key and the R key - in the dialog that opens type in winver and press enter.
Software full name and version number - as found under Help, About . . .

Also when posting please include the following where applicable:

Format and resolution of the video on the timeline or being imported
A screen shot of the timeline may help.

Also add any other information you think may be relevant.

John EB

polarapfel wrote on 1/3/2018, 6:02 PM

Hi,

I added my work environment details in my signature.

This is what MediaInfo shows for the file straight out of the iPhone 8 Plus.

In Movie Edit Pro, I chose PAL FullHD 24p 16:9 (1920x1080; 24fps) when creating the project. I tried going with both options when importing the video. In both cases, it plays back at 240fps. In both cases, when I apply the speed effect to slow it down, it plays back choppy.

thanks for the help!

polarapfel wrote on 1/3/2018, 6:17 PM

Hi John,

I also looked into that hint you gave me regarding Apple Support's feedback on their native camera app slow motion output files.

Instead of recording slow motion files with Apple's camera app, I tried Filmic Pro. There, I chose the proper record frame rate and playback frame rate. That file shows the correct information via MediaInfo and plays back correctly and smooth in Movie Edit Pro at the playback frame rate I set in the recording app. So from now on, I'm only going to use Filmic Pro to record slow motion on the iPhone.

However, I wonder if there's any way I can salvage the older slow motion footage I did in Apple's app so it plays back correctly.

thanks!

johnebaker wrote on 1/4/2018, 3:49 AM

. . . . I wonder if there's any way I can salvage the older slow motion footage . . . . .

Thanks for the MediaInfo data, the issue looks like it is caused by either the frame rate mode not being constant or the MOV file metadata is incorrectly set.

It may be possible to recover the clip by running it through a video converter changing to file format to mp4 and constant bitrate - I use MovAvi, paid for, which does a very good job of conversion.

It would be interesting to compare the MediaInfo from Filmic Pro to the Apple app data.

HTH

John EB

polarapfel wrote on 1/4/2018, 11:52 AM

Hi John,

this is the MediaInfo output for a file recorded in Filmic Pro, using the highest bitrate available and setting the recording frame rate to 240fps and the playback rate to 24fps.

thanks,

Tobias

johnebaker wrote on 1/4/2018, 3:09 PM

Hi Tobias

Thanks, it confirms my suggestion that the frame rate mode causing the issue, in the Apple clip it is Variable in the Filmic clip it is Constant.

Thanks

John EB

polarapfel wrote on 1/4/2018, 5:54 PM

Hi John,

I use MovAvi, paid for, which does a very good job of conversion.

I'm trying ffmpeg for this right now and it looks promising.

I converted the clip from mov to mp4 without re-encoding, only changing the container.

I stripped away the audio track (as ffmpeg can't deal with the aac encoding in the audio it seems).

Now, it's still running with the setpts filter to slow down the video by a factor of 10. This ffmpeg filter is supposed to not manipulate any frames, so it should result in equal quality to the input file. I can see that it still will have a variable framerate though. Let's see how that turns out. If that works to salvage those clips, I'll share the ffmpeg workflow here. I don't quite understand why, but this workload takes a long time to execute. On my machine, it goes through roughly 30 frames per second it can process.

Tobias

polarapfel wrote on 1/4/2018, 8:36 PM

OK, I found a way to make the native iOS camera app footage usable.

I'm using ffmpeg for this.

First, I convert the container format from mov to mp4:

ffmpeg -i IMG_0116_39B3F328.MOV -c copy converted_to.mp4

My example has been recorded at 240 frames per second. I want it to play back at 24 frames per second for that cinematic look. With footage that slow, I am not interested in the audio, so I'll remove that first:

ffmpeg -i converted_to.mp4 -c:v copy -an slow_motion_input_no_audio.mp4

Now, I'll run this through ffmpeg again, applying the setpts filter to slow the video down by a factor of 10. This will give me 24 frames per second.

ffmpeg -i slow_motion_input_no_audio.mp4 -vf "setpts=10*PTS" slow_motion_24fps.mp4

This can take quite some time to process depending on your hardware.

Done.

To avoid going through this trouble, I'll exclusively shoot using Filmic Pro from now on, setting the footage properties correctly in there.

johnebaker wrote on 1/5/2018, 4:09 AM

Hi Tobias

Thanks for letting us know you rescued the original footage. Variable framerate is a common issue with recording on mobile devices.

John EB

polarapfel wrote on 1/5/2018, 3:23 PM

Hi John,

While I found the solution with some digging into ffmpeg, I recon the popularity of the iPhone as a consumer video device and Movie Edit Pro with its moderate price point being aimed at the same target audience, it does make sense for Magix to invest some time and make sure they have built in tools into their enthusiast grade products to deal with the mobile footage from iPhone as such.

Not everyone has the patience and abilities to figure out ffmpeg on the command line...

Just a thought directed at Magix.

thanks for your pointer about the video properties, it led me into the right direction!

Tobias