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.

[Tom Saurus]

I am glad you got it worked out. Just be thorough in checking out the file before you delete your original files just in case.

[Seven37]

I am glad you got it worked out. Just be thorough in checking out the file before you delete your original files just in case.

Cheers pal, i always keep my original files.
The subtitle edit and losslesscut method was the easiest way..
I found ffmpeg too complicated.
Thanks again.

[Subtitles]

Good to know you have done it.
Did you need to use Subtitle Edit for synchronization of the subtitles or losslesscut took care of that when you joined both parts?

[Seven37]

Good to know you have done it.
Did you need to use Subtitle Edit for synchronization of the subtitles or losslesscut took care of that when you joined both parts?

As you probably know, Subtitle edit just extracted the sub from each video and it saved them as two seperate .srt files, one for each video.

I kept both videos and both .srt files all together in a folder.

losslesscut took care of joining the videos and the .srt files.
Ticking the 'Include all tracks?' Check box must
be the subtitle .srt files i guess.

Thats all i had to do really, the resulting mp4 has got one subtitle now for the whole joined video.
The sub is exactly the same as original.
Each of the videos in the completed video have the correct subs and are in sync.

So yeah, losslesscut took care of the joining and synchonization.

Thanks for your help pal, much appreciated.

[Tom Saurus]

Thank you for the additional information as it helps others learn including myself.

[Subtitles]

Thanks for clarifying. Will look into losslesscut. Cheers Tom for suggesting it.

[Tom Saurus]

Yes it is terrific program and I am glad it exists and is free. It is frame accurate and that is stupendous when it comes to cutting out unwanted parts of a video. Also it has the merging tool which is very handy.

[Seven37]

Thank you Tom and Thank you Subtitles, much appreciated.

[Tom Saurus]

You are entirely welcome and we benefited as well from this topic as we learned new things as well and I am sure others have and will in the future as well.