QT says 6 channel AAC, but AppleTV outputs in 2ch. VLC baffled.

[toypadlock]

so yeah, i downloaded a 720p mp4 file that plays great on my appleTV (2010), except that surround doesn't work.

i understand that this is probably to do with its audio track being a 6ch AAC, which my awful old receiver probably can't handle (it's connected via optical).

how do i get it to output in 5.1?

(also, VLC seems to think the file is stereo, which is weird).

thanks in advance!

 

[peterjcat]

AppleTV can't handle 6-channel AAC, so you'll only get the stereo downmix.

The only way to get multichannel out of an AppleTV is Dolby Digital (AC3).

You should be able to re-encode the audio with MKVTools.

 

[williedigital]

Technically True

But in the old Apple TV (and the current from what I can tell), the device would convert 6-channel AAC to Dolby Pro Logic Surround. I can certainly hear it doing something "surroundy", depending on the file. I can't tell if the conversion is to "old" DPL or DPLII, but there is some understanding of the multichannelness to my ears.

 

[toypadlock]

this didn't light up the surround light on the receiver, it was definitely 2ch. thanks for the help though, I foolishly assumed MKVtools would only work with .mkv files.

 

[peterjcat]

this didn't light up the surround light on the receiver, it was definitely 2ch. thanks for the help though, I foolishly assumed MKVtools would only work with .mkv files.

Yeah it's maybe not the best name for the package (though much better than the old name!).

 

[williedigital]

it wouldn't

Yeah it's maybe not the best name for the package (though much better than the old name!).

A DPL/DPLII mode stays on regardless of what the receiver is being fed. It will even attempt to simulate surround effects on stereo audio.

Subjectively I would say that, on a scale of surround "perception" by the user where stereo is a 1 and proper 5.1 ac3 is a 10, stereo audio run through a DPL system is a 2, stereo run though a DPLII system is a 3, DPL encoded stereo run through a DPL system is a 4, and DPLII encoded stereo run through a DPLII system is just below a 7.

The only question for me is whether the apple TV decoded 5.1 aac as DPL stereo or DPLII stereo. My ears would say DPLII, but I can't say for certain.