Join two MP4 video files & include embedded subtitles.

[Seven37]

Hi all.
I have two mp4 files, each one has its own embedded subtitle, is there a way
to join both mp4's, keeping both subtitles for each mp4?
To be more specific, the videos are from a DJI Mini 2 drone,the subs embedded in the videos is drone telemetry info.

Thank you.

[Tom Saurus]

I think you should have a back up copy of these two files just in case. But I think you try Losslesscut it has the ability to merge files. The thing to remember is the specs have to match up for each file. It is a terrific program. I can't speak to subtitles though as all the files I have worked with so far haven't had any.

[Subtitles]

If by embedded subtitles you DON'T mean hardcoded or burnt-in subtitles, then you should be able to extract both subtitles using Subtitle Edit or ffmpeg.
Notice the time length for each subtitle, as you are going to need this later on.
Join the two parts using ffmpeg and command line.
ffmpeg -i "concat:input1.mp4|input2.mp4.mp4" -c copy output.mp4
Check to see if you have subtitles in the combined mp4 file.
You can disable the subtitles while playing the final combined file later on using VLC.
Now we go to the extracted subtitle files.
In Subtitles Edit, navigate till the end of the first part. It should be in sync but after that you will probable get out of sync in the second part.
Using Subtitle Edit, combine both subtitle files. It is probably easier to use Note Pad for this if you are not familiar with Subtitle Edit.
click on Synchronization in the top menu
Then select all the subtitles that belong to the second part and use
Adjust all times. Add the length of the first part and use Selected lines only and Show later.
Save the file as combined.srt and check that it is in sync this time. If not, make a note of how much time the second part is out of sync and repeat.

Hope that this wasn't too confusing.

[Seven37]

Hi Tom Saurus.
I am looking to preserve the Subs on two joined mp4's, thanks anyway, i will look into lossless cut.

[Seven37]

Hi Subtitles.
Thanks for your reply, but your method looks complicated, not sure if i can follow the steps, although i will read your post again and try understand the steps.

[Subtitles]

No problem.
I am not familiar with telemetry sub. Are they like ordinary text for spoken audio?
Can you post here a sample so we can understand your problem better?

Just another thought. If you can burn (hardcode) the subtitles of each part then you will not have any problem with sync.
Simply use what Tom suggested or the ffmpeg method to joint the two files.
You can use Handbrake to burn the subtitles for each part.

[ProWo]

Hi all.
I have two mp4 files, each one has its own embedded subtitle, is there a way
to join both mp4's, keeping both subtitles for each mp4?
To be more specific, the videos are from a DJI Mini 2 drone,the subs embedded in the videos is drone telemetry info.

Thank you.

Try clever FFmpeg-GUI.
Start the app, follow the instructions for the first start.
Then click Join media files, drag your 2 mp4 into the grid and click join.
Done.

[Seven37]

Hi ProWo.
Thanks for your reply.
So, will clever FFmpeg-GUI do both subs when the videos are joined?

[Seven37]

No problem.
I am not familiar with telemetry sub. Are they like ordinary text for spoken audio?
Can you post here a sample so we can understand your problem better?

Just another thought. If you can burn (hardcode) the subtitles of each part then you will not have any problem with sync.
Simply use what Tom suggested or the ffmpeg method to joint the two files.
You can use Handbrake to burn the subtitles for each part.

Its just ordinary text.
letters and numbers that change during flight, things like speed,GPS coordinates,height etc etc.

[Subtitles]

Try to extract the subtitles and then burn them in using Handbrake. That means hardcode them.
This way both parts would be in sync after they are joined.

[Seven37]

Ok, will download clever FFmpeg-GUI and also FFmpeg, and start from there.

[Seven37]

I have have successfully done it now.
I used 'Subtitle Edit' to extract the subs as .srt files, then used 'Losslesscut' to Merge both videos & checked the 'Include all tracks? box, then hit Merge.
So, thanks to Tom Saurus for suggesting Losslesscut and thanks to Subtitles for Subtitle Edit.