I might be a little confused; I want to run 5.1 Dolby signals from an HTPC that is hooked up to my A/V receiver. I want the A/V receiver to handle the decoding so the Dolby Digital light comes on. I was planning on using the Optical Audio (SPDIF) port out the HTPC and plug into the A/V receiver. But I keep seeing things like the quote below that say optical only has enough bandwidth to handle 2 channel audio? As I understand it, 2 channel is stereo - i.e. Left and Right speaker only... Does this mean I can't get true 5.1 through an optical SPDIF cable?

I'm assuming you're using the PS3 as your Blu Ray player. The PS3 does not have multichannel analog outs, so the only way to get lossless audio from the PS3 is through HDMI. The PS3 will do the decoding internally and output the HD audio as multichannel PCM. It can't do this over optical, because optical only has enough bandwidth to handle 2 channel PCM. The only way to do it with the PS3 is via HDMI. Hope that helps.

You'll be fine. Optical, using the S/PDIF protocol, can transmit DD and DTS 5.1 soundtracks for your receiver to decode. It can transmit two channels of PCM. But, it cannot handle multichannel PCM or lossless codecs such as TrueHD and dts-MA.

The answer to the thread title: no, it's not true. Optical S/PDIF (toslink) is routinely used to transport standard Dolby/DTS 5.1 digital audio signals between players and receivers. And that's because Dolby/DTS 5.1 digital audio is not typically passed as PCM, it's passed as a lossy-encoded bitstream, which is converted in the AVR. If you convert to 5.1 PCM in the source device, and try to pass it to the AVR, then you can't use optical or coaxial S/PDIF, you have to use analog or HDMI.

So set your HTPC to pass 5.1 DTS/Dolby as bitstream ('raw') data, and you're set (for the standard lossy codecs; for the new lossless Dolby/DTS codecs, or multichannel DVD-Audio or SACD you'll have to use HDMI or analog).

the quote you are referencing is specifically referring to LOSSLESS audio from blu rays. normal 5.1 dolby digital and DTS has been going out over optical for 10+ years....

Someone might want to inform the studio gearheads that they have been doing the impossible - as they use the same connector to do 8ch/48kHz/24b uncompress audio for a while now.

http://en.wikipedia.org/wiki/ADAT_Lightpipe

It has nothing to do with bandwidth limits in consumer products - it has to do with copy protection under the banner of the HDMI cable.

It has nothing to do with bandwidth limits in consumer products - it has to do with copy protection under the banner of the HDMI cable.

Hi Kevin,

I'm afraid I missed your point. What does HDMI cable have to do with this question about Optical Audio (S/PDIF) cable?

I understand from your reference that intrinsically Toslink cable can have a bandwidth that perhaps exceeds the S/PDIF protocol. Is that the point you were making?

Thanks.

Larry

Hi Kevin,

I'm afraid I missed your point. What does HDMI cable have to do with this question about Optical Audio (S/PDIF) cable?

I understand from your reference that intrinsically Toslink cable can have a bandwidth that perhaps exceeds the S/PDIF protocol. Is that the point you were making?

Thanks.

Larry


I think the point that he was trying to make was that instead of simply introducing S/PDIF v2 that would carry all the HD audio stuff, the big CE vendors and studios insisted on locking people into a yet to be perfected standard (HDMI, which is on it's 4th revision already?) primarily as a content protection solution.


It's kinda like USB.. first we had USB 1, then USB 2 which was fully backwards compatible with older devices but had many times as much bandwidth and very few headaches.

Instead of simply revising the tried, tested and true S/PDIF to support higher bandwith, HDMI came along. It's like reinventing the wheel. There was no NEED for HDMI other than content protection and was sold to consumers to reduce clutter behind their TV.

Nobody ever had to ship off their receiver for a flash because their SPDIF wouldn't handshake properly :rolleyes:

Right - they could have simply adopted ADAT from studio gear which uses the same port for uncompressed unprotected multichannel - instead they jumped in the HDMI bandwagon because of copy protection - and the idea of one AV interconnect. Of course anyone with audio/video display, speakers & processors as separates (just about everyone) knows that is not really an advantage but rather a hindrance!

The point is that optical is NOT bandwidth limited - it is politically limited.

The point is that optical is NOT bandwidth limited - it is politically limited.


The same arguement is true for 1080p over component vs 1080p over HDMI (excluding the deep color discussion)

In theory DeepColor can be implemented on analog as well - it just needs circuits updated to allow over/under voltage since that is what Deep Color does - lets the same signal go over/under into numbers that used to be errs.

It is all silly because the pirate would rather get an HDCP ripper anyways instead of the more expensive analog redigitizer resulting in lesser quality ... unless they are the pirate that just holds their mic/camera up to the display!

Even more silly when you realize video prohibits analog favoring digital - whilst audio requires analog thus dissing old digital favoring new digital.

It is all silly because the pirate would rather get an HDCP ripper anyways instead of the more expensive analog redigitizer resulting in lesser quality ... unless they are the pirate that just holds their mic/camera up to the display!


not just pirates but those of us that have $$$ in full house HD over component wiring. I have a couple HD Fury products myself ;)

Never did the comparison vs a more expensive analog redigitizer but HD Fury is still pretty sweet.

btw, I will stop now....this is about Audio not video.