10-18-2007, 02:29 AM

Hi,

I am planning to build a home theater system using a Mac Mini. I am planning to connect the sound via an optical cable to the Logitech Z-5500 speaker set.

During my research, I found this review which says that the optical output will only pass digital surround data from DVDs to the optical output, and that the Mac Mini sound processing system is actually only stereo!!

I am currently using a PC with a surround sound card (using analog connectors). Many of my DIVX videos have surround sound. If I connect the Mac Mini to the Z-5500 speakers, will these DIVX videos be downgraded to stereo?

Thanks in advance,
Sam

10-20-2007, 07:18 PM

I did some more research. Apparently 5.1 surround sound can be encoded in video files (like AVI or MP4) as one of two formats:
1- AC3 digital (used in DVDs)
2- AAC

So far, I have gathered information leading to the following conclusions:
Using a Dolby Prologic II capable sound system (like the z-5500) connected via optical output:
1- DVDs will play back in 5.1 surround (passed through from the DVDs to the optical output)
2- AVI with AC3 encoded sound will play in 5.1 surround when played with VLC
3- AVI with AC3 encoded sound will NOT play in 5.1 surround when played with Quick time or Front Row (which uses Quicktime for video playback)

I'm still looking for information about playing video files with AAC encoded surround sound.

Information mentioned here are gathered from these two great articles about 5.1 surround sound playback on Mac and Apple TV support for 5.1 audio, and from one comment posted on this DIGG page (read comments posted by ThrillSeeker).

Additional interesting information can also be found on:
Optical Output on the Mac
Surround-Enable Your MacBook


Hope this helps someone in the future!
Sam

10-20-2007, 08:30 PM

I believe this is the solution you're looking for.

10-29-2007, 12:42 PM

Thanks for the reply SmokingFetus!

The guide you have provided does not specify which problem it is solving. It only says that it helps you to "Watch Your Video with Dolby Digital Soundtrack in Quicktime Player", but what does that mean? Does it:
Pass-on AC3 data directly from video to optical? (VLC can already do that)
OR
Reincode sound (whether it was AC3 or AAC) into AC3 and output it to optical? (That would solve all problems!)

It is ironic that iTunes videos all have surround sound encoded using AAC, but Mac's cannot seem to be able to pass on the 5.1 channels through the optical output.

What we need is a way to encode sound on the fly into AC3 and pass it on through the optical output. How can we do that on a Mac?

Here is how to do it on Windows! (and another way)
Here is how to do it on Linux!!!

So how can we do it on Mac's?????