View Full Version : Has anyone tried the HDMI output for surround?

Mar 25, 2007, 08:45 AM
I know that the SPDIF output will only pipe out PCM, even from 5.1 AAC files, but I was wondering if anyone has hooked an AppleTV to a receiver and tried to get discrete surround that way. But if you are going to try, then you will need to try either some HD trailers from Apple's site(not all trailers have 5.1), or a DVD you ripped and encoded with 5.1 AAC.

If the AppleTV doesn't support surround over HDMI, then this product has many flaws.

Mar 25, 2007, 11:18 AM
Some of you folks with the :apple: tvs interested in the surround sound question might want to look at this article (http://www.roughlydrafted.com/RD/RDM.Tech.Q1.07/D1925D1E-7479-4F44-B3B7-472113B366D8.html), from which the following is quoted:

(Keep in mind the following is talking about iTunes itself, not Apple tv)

"Both Dolby Digital and DTS can provide six separate channels of sound, designed specifically for 5.1 audio sound systems. Using a decoder, DVDs can present true surround sound, with different sound from each of the two front stereo speakers, two rear stereo speakers, a center mono channel for dialog, and a mono subwoofer.

The Dolby Surround on movies from iTunes is actually four channel audio that is matrix-encoded into stereo. Normal players will play the audio as standard stereo, while playback systems with support for Dolby Surround Pro Logic will decode the sound into four channels, for discrete front stereo and rear and center channels."

So, since :apple:tv relies on iTunes for its source (at least in the unhacked form) it appears the best you'll get (from standard iTunes "surround sound" content) is matrix-encoded stereo that *might* be able to be decoded via a Dolby Surround Pro Logic receiver. Still, it'd be interesting to hear if this much is possible...

...edited to add...

Here's a QuickTime 5.1 surround sound demo (http://www.synkaudiostudios.com/downloads/quicktime-demos/season_one_surround_demo_a.mov) from Synk Audio (http://web.synkaudiostudios.com/blog/2005/11/10/musicbed-dv-surround-sound-demo.html) that plays back in surround sound via a sound card with 6 discrete outs from within iTunes on my Mac... Maybe this would make a good 5.1 test file some folks with Apple TVs can try out...

Cult Follower
Mar 25, 2007, 11:44 AM
I like HDMI ecause it only requires one cable.

Mar 25, 2007, 12:12 PM
I like HDMI ecause it only requires one cable.

That's great. Do have a receiver with HDMI inputs/switcher that you could try a multichannel AAC program?

Mar 25, 2007, 01:06 PM
Seems like you'd need two HDMI cables to realize 5.1 sound (and have a receiver w/Dolby Surround Pro Logic decoding via HDMI) like these diagrams indicate (http://www.4electronicwarehouse.com/connectionguides/media-center-pcs.html)... or am I missing something here?

Mar 25, 2007, 01:23 PM
Yes, you do need two. It goes for the PS3 Uncompressed PCM audio. It only works through HDMI, so one HDMI cable from the ps3 to the receiver and another to the tv.