Editing slow motion videos

Any idea how to solve this?

1) Are you opening these files in the QT X Player?

Only certain player apps are programmed to display the secondary slow/normal motion control bar. (E.g., QT 7 and VLC won't.)

2) Do all of the files that don't display the secondary control bar still have a frame rate greater than 60 fps?

Display of the secondary control control bar is only triggered if the files are recognized as high speed recordings. Any editing, export, or conversion workflows that lower the encoded frame rate below the critical limit would disable this control.

These are normally the two biggest problems.

Here is one of those I'm having trouble with:

Thanks for posting the sample file. It saved a lot of time exchanging questions and answers.

Any possible explanation?... I don't remember, maybe instead of transferring them with the "Image Capture app", I used instead the new Photos.app and it messed with my files? It never happened before with iPhoto or Aperture.

The basic answer is...

At some point in your workflow the original file (with the secondary slow-motion slide control) was saved (read as "exported") with the normal motion and slow motion segments set to the positions as they are currently rendered during playback. This operation used a "Frame Rate: Same as original" strategy which preservered the "playback" frame rate of the various secondary control defined segments creating a file with a total average recoded frame rate of 43.65 fps—a frame rate below the critical threshold required for the QT X player to now display the secondary control.

MORE BACKGROUND: While your original files have a recording frame rate on the order of 240 fps, the QT X player achieves the slow motion effect by "playing" all or a portion of your 240 fps file back at a much slower rate as defined by this secondary slide control. And, even though the QT X "Inspector" window reflects the "effective playback" frame rate as the combined total average frame rates of your "normal" motion and "slow" motion segments, the actual "recorded" frame rate of the original file remains unchanged. Unfortunately, your workflow as explained above, re-stores the "effective playback" frame rate as the permanent total average frame rate—basically locking in the "effective playback" frame rate as the "recorded" frame rate for the file.

To demonstrate the change on your computer, simply open and compare the frame rates of an original and "re-saved" file in both the QT X and QT 7 (or similar) media player apps:

In the case of your sample file, both QT 7 and QT X players reflect the same 43.65 fps frame rate meaning that the effective playback and recorded frame rates have the same value. On the other hand:

In the case of my own 720p120 sample file, QT 7 Inspector window indicates the file's actual recorded 119.88 fps frame rate while the QT X Inspector window reflects the current "effective playback" frame rate of 40.87 fps as currently defined by the QT X secondary motion speed slide control. This is a quick test that should easily identify and confirm which files have been "modified" somehow on your system.

Now, my question is how that happened?

Do you think it has something to do with how I transferred the clips from the iPhone to the Mac?

I'm suspicious of the Mac "Photos.app".

I really can't say for sure without knowing your specific Photos workflow for both the working and problematic files. If all files are processed in the same manner by Photos but some are problematic while other are not, I would logically look elsewhere in my workflow for the cause of the problem.

I use a completely different workflow. I copy my high-speed raw recordings directly to a RAID unit for non-linear editing. Basically I pre-edit these files using the free GoPro Studio app to create intermediate content with applied fast, normal, and slow motion effects targeted at a specific frame rate for mixing with content from other sources using traditional NLE video editors like iMovie or FCP. In this way I can more easily create fast-fowarding effects between normal playback sequences, add "instant slow-motion replays" or apply similar motion-based actions in the main video editor without modifying or damaging my master raw files.

Any idea why?

Based on the image you included and the stated 230 fps frame rate I'd say the in and out values (not displayed in the bottom bar) were lost. If the pointer were at the very beginning and end of the bottom bar then you would normally expect the "playback" frame rate to read 239.76 fps. Since the stated frame rate is on the order of 230 fps (i.e., not in the default no "sidecar" range), my guess would be that either the video file or the associated AAE file is corrupted. If the "sidecar" (AAE) file is corrupted, I would probably delete it and the video file should normally fall back to its default slide "in" and "out" settings for the central slow motion playback segment. If the video file is corrupted I'm not sure what you can do as I've not run into such a situation. (I.e., I would probably go back to my original raw footage file and use the "Save" option to create a new copy of the "sidecar" and video files rather than trying to re-export the "corrupted" file to the original frame rate even if the file were otherwise playable.)

So where is this solved? I have the same issue and I can't see any fix in one of these posts.

It's quite annoying to stumble google for hours to find this single post where someone has/had same issue like me and didn't getting any fix.

Please send some help.

Greetings

So where is this solved?

The "solution" depends on your goals. If you want to view a file with some or entirely in slow motion, then use a media app like the QT X Player. If you want the video to to be treated as a "normal speed" 240 fps file, then use a media player that does not include "slow-motion" recognition features. In a similar manner, if you wish to edit the file with and/or without slow-motion segments, then use an editing app like the free GoPro Studio or buy Apple's iMovie app. Again, if you wish to edit without slow-motion segments, then use a video editing app that ignores these capabilities. Basically, some apps recognize high-speed frame rates and allow the user to play, edit, and/or export these recordings at a fixed frame rate other than that used during recording. For instance, a 240 (or 120) fps segment played/exported at 30 fps plays the original data at 1/8th (1/4th) normal playback speed. Using an editing app compatible with such high-speed recordings allows the user to mix and match frame rates during editing to provide special effects to enhance video content. Using a dedicated video editor here is much easier than creating and merging segments exported as individual files using an app like the QT X Player which I assume is what you are trying to do sans the segment export workflow.