Merging Video Files

[ozanarslan]

Hi all,

when I try to merge my 1 minute Viofo A329's videos using the "MKVToolnix" program, no matter which format I convert them to (mp4, mov etc.), i lose the embedded GPS data that was present in the original files in the merged file. For example, when I open the original 1-minute videos using the "Dashcam Viewer" program, I can access the GPS data, such as speed, altitude, my location.. However, after merging the videos and open it with Dashcam Viewer, these datas are no longer visible/available.

Remember, when i use merging with MKVToolnix software, i'm not encoding or re-encoding them. Just merging with such as "Mkv Muxer" output format.

Has anyone here successfully merged these files without losing the GPS data?

 

[lufa6977]

I would expect this to be related to MKVToolnix and not the VIOFO file stream. May be a limitation of the tool or you may need to look at command line options and adjust to
capture embedded metadata.

MKVToolnix FAQ

 

[DT MI]

when I try to merge my 1 minute Viofo A329's videos using the "MKVToolnix" program, no matter which format I convert them to (mp4, mov etc.), i lose the embedded GPS data that was present in the original files in the merged file.

I would expect this to be related to MKVToolnix...

I would agree. Have you tried any other video editing programs to merge the files? There are a number of free ones as well as paid programs that have free trial periods.

 

[Nigel]

Has anyone here successfully merged these files without losing the GPS data?

Not that I am aware of, must be possible though!

 

[DT MI]

Have you tried merging the videos using Dashcam Viewer? I believe all versions of the program have that function.

 

[ozanarslan]

I would expect this to be related to MKVToolnix and not the VIOFO file stream.

Yes lufa6977, exactly it's related to MKVToolnix software. While merging, somehow program not copying embedded orginal Viofo files' metadata to the merged new file.

Have you tried merging the videos using Dashcam Viewer?

DT MI, i didn't know that Dashcam Viewer had such capabilities. I’ll give it a try as soon as possible.


Thanks for your answers. When i find the right software, I’ll let you know. 👍

 

[Alex93]

Hi,

Previously, I had tried using losslesscut and ffmpeg, but the GPS data was lost.
I was able to extract the GPS data with exiftool, but so far I haven't been able to combine it with ffmpeg...

I finally found a small utility program that can merge multiple viofo's videos without losing GPS data.
However it's only in command line software and it's very basic but it works.
It is available here:

GitHub - gyroflow/mp4-merge: A tool and library to losslessly join multiple .mp4 files shot with same camera and settings

A tool and library to losslessly join multiple .mp4 files shot with same camera and settings - gyroflow/mp4-merge

github.com

The versions for your OS are available here:

Releases · gyroflow/mp4-merge

A tool and library to losslessly join multiple .mp4 files shot with same camera and settings - gyroflow/mp4-merge

github.com

Example: To merge these three files in Windows:
c:\tmp\viofo\2025_0727_143048_000973F.mp4
c:\tmp\viofo\2025_0727_143048_000975F.mp4
c:\tmp\viofo\2025_0727_143648_000973F.mp4

We download mp4_merge-windows64.exe and we put in c:/tmp/viofo
We launch ommand line prompt.

cd c:\tmp\viofo
mp4_merge-windows64.exe 2025_0727_143048_000973F.mp4 2025_0727_143048_000975F.mp4 2025_0727_143648_000973F.mp4 --out merged_video.mp4

The merged_video.mp4 file keeps the telemetry and it can be be viewed in the ViofoPlayer application.

Until something better comes along, it's a free solution that works.

 

[Alex93]

Hi,
I finally created a GUI in Python to control mp4_merge.
It was a good opportunity to practice using FreeSimpleGui.py 😉
For example, in this screenshot, the merging create à 20 Go viofo video file.

If you want to try it,, two options:

1/ An executable file
I created an one-file executable file called "GUImp4merge.exe"... But you will need to disable your antivirus because it may be detected as a virus, but it is a false positive.
the link is here and It's compressed in .rar format. You need to "unrar" it with 7zip, for example, which is free.
guimp4merge_v1.rar
rar file SHA1:
Size: 9813718 octets (9583 KiB)
SHA1: 3f6713245af1fb8fdc172397d7f0840cc8bb3791
Edit 2025/08/25:
Too many problem with the PyInstaller with the false positive virus detection!
So i've recreated a new package with the nuitka compiler that avoids this false positive issue!
You can download the package here and this time in ZIP format:
GUImp4merge_v1.0.zip
Once downloaded, unzip it, go to the subfolder GUImp4merge.dist.v1.0 and run GUImp4merge.exe

2/ to run the source python file (version 3 minimum)
If you prefer the Python source file, here it is:
GUIp4merge.py
To run it, you will need to have previously installed the FreeSimplegui.py library.

*** HOW TO MERGE WITH THIS APP ****
You will need to indicate where mp4_merge.exe is located on your system, which you will have previously downloaded in the post above.
Next, Once you have selected the files and chosen the destination directory, you can click on the ‘merge’ button.
Of course, you can modify the merge filename and/or the output folder.
A progress bar will show you the merging in progress.
A final pop-up will tell you if everything is OK or if there has been a problem.

 

[ozanarslan]

Hi Alex93. Thank you for your very detailed and informative message. I'm sure it will be very helpful for those who are experiencing this issue or might encounter it in the future.

 

[kamkar]

I do not mind loosing embedded data so i just use a regular video editing program, all the data i would need is there on the screen embedded in the video, so speed / time and date.
I lost interest in the dedicated dashcam softwares a long time ago.