Cannot activate "fractional fps" option

Fabrizio Lorito

New Member
Hi
I want to make a timelapse screen recording and to this purpose I'd like to use the video setting "Fractional fps value
However, this option is present but not selectable
Can abybody help me?
Thanks
/Fabrizio
 

ModernManuh_

New Member
First time I see this but I can't understand why you would do a timelapse with fractional recording. That option should only be used for old TV services if I rember correctly and even if I'm wrong about it, I'm sure you don't need it. I suggest using integer value and then speed up the clips in a video editor (like Premiere Pro for example).

This doesn't answer to your question, but I can't figure out the problem without a log file!


EDIT: Just for curiosity, are you italian too?
 

koala

Active Member
@Fabrizio Lorito Many settings are locked as long as you have an active output such as a recording, a stream, the virtual webcam or some plugin as the NDI plugin. Stop that output and the setting becomes editable.

@ModernManuh_ Timelapse mean speed up the recording, so you want to record only very few frames per second. For example you might want to record only 1 frame in 2 seconds (0.5 fps), so you configure a fractional fps of 1/2.
 

Fabrizio Lorito

New Member
@koala Thanks. There was probably an active output. Now the fractional fps is available.

Is there any way to timelapse sampleing 1 frame each n with fractional fps but create the output file at say 24fps?
I can solve this in a video editor but this would ghelp me skip one processing step...
 

koala

Active Member
You cannot create the timelapse with OBS directly. You need a postprocessing step to actually speed up the video. If you record with 1/2 = 0.5 fps, OBS actually writes only 1 frame every 2 seconds, resulting in very compact files. However, the fps is recorded with the video file, so the media player knows that it should show every frame for 2 seconds, so the display time of the video is exactly the recording time.

If you want to speed this up to 24 fps, you need to apply a postprocessing step that speeds the video up by a factor of 48, so 0.5 fps becomes 24 fps. You can use ffmpeg for this, see this post of mine and the follwing post:
 
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