Extracting Surround Sound from HDMI Signal....


My wife is technologically challenged so I have connected the HDMI outputs from my ATT/Uverse box and Apple TV box directly to the TV. This makes it simple for my wife to use as she doesn't need surround sound for most things. (The TV is an older Mitsubishi rear digital projection model with two HDMI input ports.)

This is all well and good, but because of the handshaking between the TV (which will only recognize stereo audio) and the two boxes, the HDMI outputs from the ATT and Apple boxes default to PCM stereo. And even though I've got optical taps from both boxes going to the optical inputs on my Marantz receiver, the receiver only gets a PCM stereo signal, because the TV is telling the boxes that it can only process PCM stereo.

So, is there a way, a box perhaps, that I can put between the ATT/Apple boxes and the TV that will extract a surround sound signal that my Marantz can utilize and still provide stereo sound to the TV?

In other words, I'd like to have the TV work on it's own with stereo sound and not require my wife to turn on and fiddle with the Marantz receiver. And then, if we want to, simply turn on the Marantz and add surround sound to the mix.

Thanks for all suggestions!

Showing 2 responses by wmartinb

Theo: I'm not sure what you're suggesting. My current setup has the ATT box going directly into one HDMI input on the TV and the Apple box going directly into the other HDMI input. That makes it simple for my wife, but since the TV can't process/decode multi-channel audio, both the ATT and Apple boxes default to PCM stereo.

I found this on the internet: http://www.allaboutadapters.com/hddodtsdihdo.html

It appears that you can throw a switch and force the optical to output one of several formats. I'm thinking this might work for me, but I need to call them and see if I will still get a pass through of stereo audio to the TV if the switch for the optical output is set for 5.1

The quest continues.
So I called allaboutadapters and asked a few questions. Apparently, this adapter will extract surround sound from an LPCM audio format and still send stereo to the TV. Here are the gotcha's:

1. The source (from the Apple or ATT box) must output LPCM audio format. It won't work if the output is any other standard.
2. If using the Toslink output on the adapter box, it will only output Dolby Digital 5.1.
3. Is using the analog outputs on the adapter box (4 mini jacks supporting 7.1), you can get LPCM 8 channel, LPCM 7.1, LPCM 5.1, and LPCM 2 channel.

So, now I need to find out what standard the ATT and Apple boxes output and I need to find out what my Marantz will decode. (I know that it can handle 5.1 with no problem, but I don't know about LPCM surround sound signals.

I wish manufacturers would make things simple and know that not everyone wants to or can fire up their surround sound system when they want to watch a little bit of TV. Designing HDMI devices to talk to each other is all well and good, but not allowing multiple audio formats to run simultaneously is a big mistake. At the very least it should allow 2 channel to coexist with whatever multi channel standard is being used. Grrrrr.....