No audio for mp4 files in Quicktime and ITunes but works for VLC

macos macbook-pro mojave vlc

Solution 1:

MP4 is a container format,the audio codec format could be aac mp3 ac3,etc.

iTunes and QuickTime can’t support all those codecs.You can use mediainfo to check the exact audio codec format.

You can see the link below
QuickTime compatible and non-compatible formats
Codecs supported by MP4 container

TL;DR according to my experience,probably AC3 DTS opus.
Although they are popular formats, quicktime does not support.

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