I've gone through a bunch of tutorials as well as video players (QuickTime, mplayer, VLC, MPlayerX, Movist) and haven't been able to figure out how to get AAC 5.1 to play correctly on my Mac mini or MBP to my receiver.

By default AC3 and DTS are the only formats that gets passed through to my receiver. Everything else seems to get down-sampled to stereo.

Here's some test files:

Windows and Linux both have ways to encode AAC 5.1 to AC3 on the fly so it gets passed through to my receiver, but I have not found a way to do it on my Macs. See:

I've confirmed there's nothing wrong with my AAC file. Playback on a Windows machine works and if I use ffmpeg to convert the audio from AAC to AC3, my Mac plays the audio correctly.

I did find this tutorial on macworld: http://hints.macworld.com/article.php?story=20090215033647292

But it's from 2009 and rather involved (I haven't actually tried it yet), using multiple pieces of software to get ac3 encoding on the fly. Given that it's over 4 years later, I was hoping a better solution has come about.

1 Answer 1


Apparently Plex can do this according to this forum post

"Posted 06 March 2013 - 02:28 PM I recently discovered that Plex now are able to do transcode AAC to AC3 on the fly - "under preferences for system" audio, select audio output to "digital" and of course highlight AC3 and DTS capable receiver. If you select HDMI if doesn't transcode AAC to AC3. "

I don't have the hardware to test it out though

  • I've actually looked at Plex. The tutorial from MacWorld had comments mentioning they got aac->ac3 on the fly encoding working. However either Plex has changed since 2009 or I'm doing something wrong, Plex is only a media server on Mac now and doesn't have a Mac player/app. So I can probably get it to encode to ac3 on the fly, but no way of playing it on the Mac.
    – Toland H
    May 27, 2013 at 8:35
  • Just to clarify, Plex does allow playing media via the Mac on the browser, but browser ac3 support is limited and I really don't want to have to watch all my videos through the browser.
    – Toland H
    May 27, 2013 at 8:42
  • 1
    I haven't used Plex in ages, seems like there's separate downloads for client and server now. Try the client from here maybe? I don't know what the hell they did to their app, maybe it's only meant for streaming now which is a shame. Also maybe try one of the much older versions at the bottom of the page, says integrated client/server. wiki.plexapp.com/index.php/Downloads#Mac_OS_X_-_PMC
    – Softcox
    May 27, 2013 at 8:48
  • The client is a web app. At least the official Plex client.
    – tubedogg
    Aug 19, 2013 at 1:13

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