[FFmpeg] Re-encoding VFR, stuttering output

[izbop]

Hey all,

I have been trying to re-encode a VFR video, but the resulting output looks like a stuttery mess and I'm not sure how to fix it.

I've attached a 15sec cut of the original file, along with my attempt to re-encode it. Here's what I used to re-encode:-

ffmpeg -i "original.mkv" -fps_mode passthrough "output.mkv"

...also tried -fps_mode vfr along with the -copyts/copytb parameters without success.


Appreciate any help, thank you!

[ProWo]

Your original.mkv is constant framerate progressive.
Encode it without

-fps_mode passthrough

and there will be no mess anymore.

btw:
your original.mkv is a failed reencode, it has 26.203 fps

[izbop]

Your original.mkv is constant framerate progressive.
Encode it without

-fps_mode passthrough

and there will be no mess anymore.

I'm not sure what the best way to determine if a file is VFR, but I was certain it was.. here's a probe of the original file if that's of any use.

Regardless, simple dropping the the fps_mode did not fix the stuttering output.

btw:
your original.mkv is a failed reencode, it has 26.203 fps

Yeah I thought that fps was weird too, though I assumed it was due to the source being VFR, watching in mpv I can certainly see the fps fluctuate.

[ProWo]

the best option is to look for another source...

[izbop]

This is subjectively the best source available that I am aware of for this particular content.

All I'd like to do is re-encode the video without causing the output to stutter... aaaaah it's so frustrating...

-edit-
I've just tested re-encoding with Handbrake, and surprisingly there's no stutter in the output.. which is great! though I wish I could figure out what's causing the ffmpeg output to stutter.

[izbop]

Just a quick update, the 15sec cut I made is CFR, I don't experience any stuttering re-encoding @ 23.976 fps. FFmpeg appears to be duplicating frames when I tried to preserve the source framerate which was causing the stuttery output.

The full file is mostly 23.976 with an ending credits @ 59.94 fps, which I'm not too concerned about.. so I'll proceed with 23.976.

Would still be great to figure out what Handbrake is doing differently to preserve the source framerate, but that's an adventure for another time.