Shaky videos on macOS but not PC

[MisterE]

Videos downloaded utilizing premium on macOS (currently on 11.5.2 Big Sur) are shaky or jittery.  I saw the workaround in the FAQ, however this is odd to me.  If I do this on a PC (Firefox, PC, Premium) and transfer it to my Mac, I do not have the problem of shaky video.

It isn’t just Quicktime, but viewing the videos in an app utilizing AVPlayerView (interface for viewing  the outcome is the same as Quicktime, shaky video.  So anyone looking at a video using Apple's built in viewer will see shaky video.

Yes, re-encoding did take care of the shaking BUT there must be some solution other than having to re-encode every video downloaded on a Mac.

macOS (11.5.2 Big Sur)
Video DownloadHelper 7.6.0
Platform Mac x86-64
Browser Mozilla Firefox 91.0.1
Companion app: VdhCoApp 1.6.3
Companion app binary: net.downloadhelper.coapp-mac-64

Reference AVKit :
Apple's built in control for viewing media content (iOS and maOS)

Create user interfaces for media playback, complete with transport controls, chapter navigation, picture-in-picture support, and display of subtitles and closed captions.

https://developer.apple.com/documentation/avkit
https://developer.apple.com/documentation/avkit/avplayerview
https://developer.apple.com/documentation/avfoundation/media_playback_and_selection/creating_a_basic_video_player_macos

Thank you.

[Wild Willy]

What happens when you take one of your video files that is shaky in Quicktime & play the
same file in VLC?

[MisterE]

I should have said that I did this and it plays normally.

[Wild Willy]

I've never used a Mac but since VLC can play your sample clips just fine, VDH must not
have done anything to the clips to make them, as you put it, shaky or jittery. I don't
see any conclusion but that Quicktime is somehow faulty. I must say that I have seen
Jerome mentioning in here numerous times that Quicktime should be ditched in favor of VLC
on Mac. I think you've proven to yourself that this advice is useful. If you like, I
could test a couple of these videos on Windows 7 with VLC & see what I get. I would
expect I would not see anything untoward about the clips. Just post some URLs & I'll
check them out.

[MisterE]

I didnt draw the same conclusion.  When I use VideoDownloader on my PC and transfer the file to the Mac, I do not have issues using with shaky video.

If I download a video on the Mac, it is shaky, whether on Quicktime, Preview or I programmatically view this in Apples AVKit -- ( I do development), which is why I mentioned it.

So, if I were I or another developer were utilizing the video on iOS or macOS, the end user would see shaky video.

I also re-encoded utilizing HandBrake (a program that encodes videos, which utilizes FFMPeg as the engine for reencoding), which worked.

FFMpeg is complaining about duplicate frames and missing frames.

The conclusion that I drew is that VLC is more tolerant or adaptive to what may be going on with the video.  If there wasnt something different about the video, why would it need re-encoding?

[MisterE]

I just started looking for commonalities between the VLC and FFmpeg, to see why VLC manages very well.

"The libavcodec library from the FFmpeg project provides many of VLC's codecs, but the player mainly[17] uses its own muxers and demuxers."

VLC is using libavcodec components on which, so VLC is built  on this coded as a player application.  They share a common codec.

Re-encoding fixes an issue, whereas utilizing VLC masks the issue.

Reference https://en.wikipedia.org/wiki/VLC_media_player