I needed to join several .mts file exported from my camera, with idea to get a single movie, in order to use it for further editing; important thing is that I wanted to keep the quality-without converting anything.
I’ve found this useful application, Video to Video; it is also portable so don’t need any installation, it is free and multilingual
Here,In short description, how to join .mts files:
Open application and choose tools->Join Video Files ; so push Add button and select files you want to merge
Now, after pressing ok Ok will be asked for the format you want convert; in our case, as already said, we will not do any conversion, so we choose Direct stream copy and OK
As you can see in image below, your files already appearing as a single file, then we need only to push Convert button and wait some second or some minutes (it depend on the size of your file), waiting to see status on 100% in progress column.
Therefore we obtained an unique .mts file from several files; of course same concept is valid also with any other kind of movie (i mean .avi, mt2s, etc): using Direct stream copy, application simply combine the files without any conversion (of coure you can also use it to convert )