Change pitch of mp4 files

I want to change pitch of mp4 files. I import that file and change pitch of it but can not export to the mp4.

anybody can help me?

Is this an audio only file? MPEG-4 can contain audio & video. Audacity can edit the audio and when you export you’ll only get the audio.

MP4 audio, M4A, and AAC are all basically the same thing. Assuming you’ve installed the FFmpeg library, you can export MP4 audio as M4A. Then if you want you can rename the file to MP4.

Alternatively you can add “.mp4” (without quotes) to the file name when you export, and Audacity will give it MP4 extension.