Author Topic: How to convert "Saved File Framerate" on an existing mp4 file?  (Read 6942 times)


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Can the chronos 1.4 take an existing mp4 file and save it back out to the SD-card at a *different* "Saved File Framerate"
than the mp4 was originally saved as?
« Last Edit: May 21, 2020, 01:21:56 AM by hsmore »


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Re: How to convert "Saved File Framerate" on an existing mp4 file?
« Reply #1 on: May 21, 2020, 07:58:15 AM »
Hi, without starting up my Chronos, I don't believe this is possible, you can't open a video file nor convert it with the camera itself, I think..?
(Just confirmed it, I see no tool to convert, much less even an option to open a file. The Chronos is a single purpose tool, never forget :) )

You'd need to edit the (playback) frame rate on the video file itself.

I did understand correctly, that you just want to change playback speed of a Chronos capture?
E.g. you saved the file in-camera with 120fps playback speed and now want it to playback with 30fps? Just by changing some detail in the video file structure (lossless) without the need to recode/recompress the file (lossy)?
And you are on Windows?

If all of this can be answered: yes > read on :)

If you are fine with remuxing into another container (mp4 > mkv), use MKVToolnix GUI it's very easy:

Add the file (see 01_MKVToolNix GUI.png), then mark the video part, set the new playback fps, rename the output and then re-multiplex (see 02_MKVToolNix GUI.png)

If you absolutely need to stay with mp4-container, there are a few solutions, but as far as I know, you always need to extract the raw parts first and then remux into a new mp4!

I tested a few options already (avidemux, ffmpeg GUIs like: FFWin, Avanti, QWinFF, FFMpegYAG and finally Losslesscut and XMediaRecode RESULT: Won't work like intended) and besides using ffmpeg via CMD-line (with varying degrees of complexitiy), just try this:

Use MKVToolnix GUI again ;D to change the playback fps and then convert to mp4 using AviDemux

Just open the mkv with changed fps and copy into mp4 container, see 03_Avidemux.png. That's the fastest way using windows video tools I know of, atm. And using still supported/maintained, free software. I also tested with mp4box/YAMB but the result needed a fix from avidemux, so, I skipped explaining that route.

Good luck!

All the best

PS: The Chronos itself does not allow for audio recording, the example file for MKVToolnix GUI is not a Chronos file.
« Last Edit: May 21, 2020, 08:38:30 AM by Martin »