HD Extender not passing AC3/DTS?

[ejp]

Since the extender doesn't decode DTS and my receiver doesn't decode it, I got this device: http://www.gefen.com/kvm/dproduct.jsp?prod_id=5279 ( GTV-DIGAUD-2-AAUD ). It's supposed to take digital audio (either via TOSLINK or COAX) and downmix it to 2CH stereo RCA.

Unfortunately, I can't get it to work.

If I hook it up directly to my other receiver, it decodes AC3 audio fine. Now, at this point, it looks likely that the device is at fault, but I hooked up my DVD player to this and it works as advertised.

I'm using the latest HD Extender firmware to date and I'm running 6.4.8.184. I've tried all 3 audio outputs in the setup (RCA, TOSLINK, and HDMI) and none are working.

Because the Gefen device is rather simple and hard to mess up, I'm more inclined to think the extender (or maybe server) is at fault. Can someone shed some light?

Thanks.

[voidpt]

I could be wrong. But from the specifications on that Geffen device, and the description, I do doubt it can decode a digital DTS signal and then downconvert to 2-channel analog output. It looks to support D-A convertion of digital stereo to analog stereo:
- Accepts uncompressed digital audio as input
- Samples at 32, 44.1, 48 and 96 KHz
- 2-channel LPCM (Linear Pulse Code Modulation)
- 24-bit S/PDIF incoming bitstream on left and right channels
Your note about AC3 convertion I cannot explain. From the specifications it shouldn't really be able to do it.

[ejp]

You know, as I look at it more, I think you might be right.

I chose that one over this product: http://www.gefen.com/kvm/dproduct.jsp?prod_id=4907 because it's explicitely says this one only takes 2ch digital audio.

It's quite possible they're the same exact product, but one is just renamed under the GefenTV brand. It's also quite possible that I set my DVD player to send a downmixed stream -- I'll have to continue testing.

However, the other thing is, I tried playing a 2CH ac3 file and I got nothing. Technically, this should have worked, right?

[voidpt]

I looked at the two product pages and I do think you are right about the products. From the specifications on both, I cannot find one difference. Only the ordering of the words are a little changed. And I do think that 'Note:' about multi-channel sound should have been on both.

About the 2-channel AC3. It will still be encoded in AC3 digital format. Meaning that even though it is only stereo the device receiving the digital signal must be capable of decoding the AC3 format. And I doubt the Geffen box do this. I think it only accepts an uncompressed LPCM stream.

[ejp]

Unfortunately, that's something the extender can't do, right? Send an uncompressed LPCM stream.