XBMC & AAC Passthrough

Using the lastest Eden, RC3, on top of ubuntu - I think, (this is an openelec install - I don't think it's related to the OS unless XBMC hevaes differently depending on the OS), connected to by BOSE system through HDMI which is connected to my HDTV.

I'm having an issue with AAC passthrough settings with XBMC, the audio is aac, for sure, I can see that if I press 'O' to see the stream details, and also when I press 'M' to see the progressbar.

The problem:

With ALL the passthrough options enabled(even the AAC passthrough - option is enabled) and the right devices selected the audio get's to by Bose system as LPCM 2.0 - not as AAC - and I can hear everything fine.

Update the audio settings and to change the "Audio Output Device" to something else, something that would be invalid. Playing the same video stream that has the AAC audio nothing is heard in the speakers.

If my understanding is correct the above shows the XBMC recognizes the audio as AAC but doesn't obey the "AAC Passthrough". Please not that everything works OK is I watch a video stream with AC3 as audio.

Is this a bug? Is this expected? Why is XBMC transcoding the audio to LPCM even though I confiured it to pass the AAC audio the way it has it to my Bose system?

Thank you
Not many receivers actually support AAC in passthrough IIRC

Thank you for the feedback, but is why isn't XBMC using passthrough for AAC codecs?

If my receiver doesn't support AAC and AAC passthrough is enabled I should not be able to hear anything unless I disable the passthrough, right?
Your receiver is clearly doing something to the stream which is probably convert it to LPCM since it cant handle the AAC.

I have the same problem and my receiver supports aac (denon 2113).
I really think that XBMC doesn't send the signal as pass through, ONLY through "Audio Output Device" which is not passthrough.

It does? Where, show me!


Idk, Expectations are often not how things are.

I don't see AAC listed as supported in denon 2113 Sound Formats.

In fact, I did an extensive search to find a reference AMP that did support AAC and found none. So I doubt that none exist and I'm not sure why it was ever added as a passthough format.


Here are a few models that support it http://www.hifivision.com/blu-ray-dvd-pl...e-aac.html Oh dang! ok For your car maybe http://www.sonicelectronix.com/item_3558...-62BT.html

Since when I'm changing the "Audio Output Device" to an invalid device there is no sound I think it's pretty clear that XBMC send the audio through 'Audio Output Device' and not the passthrough device.
actually i dont know if it does support it for paththrough. But just search for aac on this page and you can see that it supports aac for usb/radio etc.
No its only for ethernet interface :p

well "i dont know" because denon does not state anywhere which codecs are supported for passthrough (they do but it is incomplete since they even missed dts etc.) it is also supported for usb interface and upnp (so streaming/push and usb). I even pushed dts sound and it decoded it using upnp (that should not work)
Im not discussing this further as it seems pointless, so unless anyone that knows audio inside out can say for sure and none of the users here who are concerned (claiming iit should work) clearly dont know about this any better to make or even have info that supports the claims. Take it up with the receivers manufacturers for better docs and or better firmware.

maybe some developer cares to make a comments and Im not qualified to speak for anyone in neither technical or otherwise. I dont have any fancy receivers, mine is some generic brand that doesnt even support a whistle sound.

I suspect that the whole aac passthrough thing is largely untested for want of hardware to test on. Certainly that as also a problem for the mythtv devs.
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