Speed change doesn't work for Prores encoding

[Prince7]

When encoding using the "Speed change" filter, the "change speed" one does not work using Prores as a codec. Tried on all three Prores encoders.
"Scale output framerate" works however so the issue probably isn't the whole filter, and "change speed" does work properly when using the x264 codec.

Is this normal or is that a bug ? As using Shutter Encoder I am able to change the speed to a different framerate while encoding Prores, so this should be possible to do.Please, read the 'Infos needed to fix&reproduce bugs,..'-sticky before you post about a problem.

[Selur]

That's a bug, I usually use either Vapoursynth or Avisynth not ffmpegs filter for speed changes.
=> will look into it. (probably tomorrow evening)

Does this only happen if you only use video, without audio, or also when using video&audio? (I suspect it's a bug in the 'video only' handling when ffmpeg is the encoder.

Cu Selur

[Selur]

Had a quick go at it and send you a link to a dev version which might fix the issue.

Cu Selur

[Prince7]

Hello, I was using video + audio (to be precise, I was doing a conversion from 23,976 to 25 on both the audio and video), I'm also on Windows 10, latest Hybrid build.
The dev build you sent me works when it's the video alone, but doesn't when doing video + audio.

[Selur]

Will need a debug output to know whats happening.

Cu Selur

[Prince7]

Sent you the debug and mediainfo files in PM

[Selur]

Strange thing is according to the debug output:

ffmpeg -y  -r 25/1 -i "C:\Users\rapha\AppData\Local\Temp\Interview 2_Couper_new_1_2023-09-21@14_28_51_2810_06.mov" -i "C:\Users\rapha\AppData\Local\Temp\iId_2_aid_0_lang_en__2023-09-21@14_28_51_2810_04.aac" -metadata encoding_tool="Hybrid 2023.09.19.1" -c:0 copy -c:1 copy -map 0:0  -map 1:0  -aspect 1920:1080 -r 25/1 -f mov "C:\Users\rapha\OneDrive\Bureau\Interview 2_Couper_new.mov"

is used, so the output fps should be 25.
=> will have to do some testing

Cu Selur

[Prince7]

Yes, but the mediainfo states

"Frame rate mode : Variable
Frame rate : 23.976 FPS
Minimum frame rate : 11.996 FPS
Maximum frame rate : 1 422.222 FPS"

So there's something wrong going on here

[Selur]

That's why I will have to do some testing.

[Selur]

Seems like ffmpeg can't change the speed for prores when it's passing through the video.
-> adjusted Hybrid to add 'fps=XX' when reencoding ProRes, which should cover your use case.
(send you a link via pm)

Cu Selur

Ps.: btw. I would advise to:
a. clean
and
b. change the temp folder to a folder outside the normal Windows path to allow settings exceptions to virus scanners and thus speeding up file handling. (under Config->Paths)