I have some movies in mp4 format. They work perfectly on VLC (audio and video) but not with QuickTime and iTunes. I can only watch the video but without audio! I have a MacBook Air 2017.

  • And what codec was used in the MP4 file to encode the audio? – Marc Wilson Nov 11 '18 at 16:50

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.

  • Is there a list of codecs that QuickTime does support so someone can follow these instructions to work out whether this is the issue? – grg Nov 13 '18 at 13:02
  • @grg I updated my answer,but I didn't find the official article from Apple. – maP1E bluE Nov 13 '18 at 18:07
  • AC3 audio is supported by QuickTime, so it's not that. – Wowfunhappy Nov 13 '18 at 21:27

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