To exchange the audio in a mp4 container

[brusno]

I want to change the audio in a mp4 container and replace it with another, without re-encoding video or audio. How do I do that? Remuxing both video and audio, and mux the video with the new audiofile? Does anyone have program tips?

[Baldrick]

You can use mymp4boxgui. Load the mp4, remove the audio track, add the new audio track, save as a new mp4.

[brusno]

Yes, mymp4boxgui worked just fine. It is easy to use. I demuxed to a .h264 videofile and .aac audiofile (ADTS sound), and muxed the new sound .m4a (aac) together with the .h264 file. The reason why I wanted to exchange the sound was that the sound in the mp4 file was too loud.
Thank you.