Video lag when seeking, audio keeps going, for only a certain file

[stevenroussos]

I have an mp4 video file, 1920x1080, data rate is 4968kbps (which is high compared to most files). The Input Codec says FFMPEG.

It starts playing after a 3-4 second lag which I can accept. But when I use the fwd arrow or click on the timeline further in the audio keeps playing continuously, but the video freezes then takes a very long time 5 seconds or more, for the video to resume.

This does not happen with most files.

I've turned off hardware acceleration, turned on Fast Seek, increased file and disk caching to 600, 1000 and 1500, tried changing FFMPG Thread count from 0 to 1, 2, and 4, set the Skip Loop Filter to ALL...

Nothing affects this lag.

When I play with Windows 11 "Movies & TV" or the excellent ExMplayer5.0 there is no lag whatsoever, the video and audio both jump to the seek point instantaneously andin-sync.

But I love VLC because of the advanced playback features like A-B looping, speed changing, etc which those other players do not have.

What the heck could be confusing VLC so badly that it does this to just certain files? Are there other settings to change? Is there a way to get a new CODEC pack and force VLC to use it? I suspect it is the build-in codec that for some unknown reason is not handling this file, perhaps the extremely high data rate so badly?

I might could run the file through a conversion with WinXDVD app, or perhaps windows build in FFMPEG utilities, or maybe with VLC itself, but I'd have no idea what to tell those to do to make the file more "normal." Or are there any mp4/FFMPEG video file checkers or optimizers I could use?

This is very surprising. Any suggestions or remarks appreciated.

[stevenroussos]

OK, so used a trial version of WinX HD Video Converter Deluxe to test a conversion (5 min only) to .mkv with h264 codec and the result works beautifully, seek was blazingly instantaneous so I purchased a license and converted to whole 20min video and it works great.

It went from 800,000 mb to 2gb though, which isnt really an issue. But is there another format using h264 that might be smaller?

Anyway, I'd appreciate any feedback on why VLC had such a problem with this file.

[Lotesdelere]

Please open Tools -> Messages (set Verbosity to 2) before you start the playback, and then paste the full resulting log here or on Pastebin.com or on Justpaste.it if it's too long.

Also upload a short sample of your original problematic file to WeTransfer.com or Disroot.org and then post the link to the file here.
https://wetransfer.com
https://upload.disroot.org