[FFmpeg-user] convert mkv to mp4

[KoSza]

Hi,

I would like to convert mkv to mp4, because my LG does play only mp4 in
DolbyVision.
I would like to keep all subtitles, all audio tracks, I just ony want to
change container, and don't want to modify anything.

I have ffmpeg on my Synology DS423+, if I use the following command

ffmpeg -i movie.mkv -codec copy movie.mp4

The file is done, but TV does not play it.

If I try
ffmpeg -i movie.mkv -map 0 -c copy movie.mp4
I got an error.

If I use my XMedia Recode software, it works well, but I have to use my
computer. I don't want to do that always.

What is the right process to changing only the container and keep
everything unchanged?

Thank you