# Remux changes framerate?



## Jarod997 (Jan 15, 2018)

I'm recording at a fixed FPS (.mkv 30 FPS) and when I remux, OBS changes the file to a variable framerate (.mp4) file. Lightworks requires a fixed framerate (and the free version is quite limited to file formats). Thus, I have to use some third party program to do the conversions - which I'd prefer to not have to do. The other option (I suppose) is to record direct to .mp4 - but again, I'd prefer to not have to do that.

I'm wondering why doing the remuxing is changing the framerate type (from fixed to variable).

As some feedback (and perhaps a request), it would be nice if we could have an option (checkbox?) to enable something like "Keep original framerate".


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## dodgepong (Jan 15, 2018)

Remuxing doesn't change the underlying h.264 video file. Remuxing takes the video file and the AAC audio file and moves it from a MKV container to an MP4 container, which is why it is so quick.

How are you checking the framerate before and after the conversion?


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## Jarod997 (Jan 17, 2018)

A tool called Mediainfo: https://mediaarea.net/en/MediaInfo
It's quite handy.
Though, don't get me wrong, I really do like that the remux goes by quickly - and if all it is doing is changing containers, then yes, it should go by quickly.


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## Jarod997 (Jan 17, 2018)

Here's some clips from the program:

From an .mkv file:
Frame rate mode : Constant
Frame rate : 30.000 FPS

From the remuxed .mp4 file:
Frame rate mode : Variable
Frame rate : 30.000 FPS
Minimum frame rate : 29.425 FPS
Maximum frame rate : 1 024.000 FPS


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## Jarod997 (Jan 17, 2018)

Should I pop this into the Bug Reports section?


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## dodgepong (Jan 17, 2018)

OBS uses FFmpeg under the hood to do the conversion, so it might be an FFmpeg quirk. Feel free to submit an issue on the bug tracker here: https://obsproject.com/mantis/


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## Osiris (Jan 18, 2018)

This happens with command-line ffmpeg too, so I don't think it's some bug with OBS.


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## Jarod997 (Feb 1, 2018)

Actually, I'm now wondering how OBS is saving my .mkv file. Doing some more editing today and Windows explorer (bear with me here) is reporting that my .mkv files are 1000 FPS files. EyeFrame is saying that my files (when I import them) are 1000 FPS files (the "Rate" column initially says 1000 for each of the files I drop into it). MediaInfo says they're 30 FPS Constant files. I'm wondering if somehow OBS is saving the files as constant framerate files but somehow writing some "codec header" info saying they're variable rate files.
More info from various programs:

While playing in VLC it reports under Codec information "Frame rate: 1000" (it doesn't seem to report "live" info)
MPC-HC (x64) shows pretty much 30 FPS (+0.100/-0.005 ish) live while playing
ffprobe (from ffmpeg site) reports the .mkv file as 1k fps, report follows:



Spoiler



Input #0, matroska,webm, from 'test.mkv':
  Metadata:
    ENCODER         : Lavf57.84.100
  Duration: 00:00:00.97, start: 0.000000, bitrate: 375 kb/s
    Stream #0:0: Video: h264 (High), yuvj420p(pc, progressive), 1280x720, 1k fps, 60 tbr, 1k tbn, 60 tbc (default)
    Metadata:
      DURATION        : 00:00:00.966000000
    Stream #0:1: Audio: aac (LC), 48000 Hz, stereo, fltp (default)
    Metadata:
      title           : Track1
      DURATION        : 00:00:00.789000000


That was on a 1 second test file I made (purely for the small file size), but it reports the same on a 1 hour 23 minute video I made yesterday as well.

Something isn't being written correctly to the .mkv files methinks.


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## Jarod997 (Mar 5, 2018)

bump?


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