why isn't there enough bandwidth to carry HD codecs in optical/coax?

[BlahBlahYouToo]

it surely can't be the medium can it?

 

[DaveSimmons]

Yes it can be. SPDIF was introduced to carry just 2-channel PCM at 20-24 bits and 44.1 or 48 KHz.

Wiki - http://en.wikipedia.org/wiki/S/PDIF

But if you google "SPDIF bandwidth", you'll see forum posts saying the problem isn't the cable itself, it's the hardware at both ends of it, the soundcard and receiver.

 

[vi edit]

I thought it was more of a rights management issue than a bandwith one.

 

[BlahBlahYouToo]

the specification yes, but the physical medium itself is not maxed out, is it?
i'm using a very generalized argument but coax is copper and toslink is optical which allows for a lot more bandwidth, does it not?

 

[sdifox]

the specification yes, but the physical medium itself is not maxed out, is it?
i'm using a very generalized argument but coax is copper and toslink is optical which allows for a lot more bandwidth, does it not?

In this case, the copper has more bandwidth. Remember the "fiber" in toslink is plastic

 

[mmntech]

I thought it was more of a rights management issue than a bandwith one.

This is a huge part of it I think. TOSLINK (fibre optic) theoretically can handle 125mbps at 24bit. Even the original could handle 3.1mbps so yes, it can technically handle HD audio.
http://en.wikipedia.org/wiki/TOSLINK

 

[alcoholbob]

It doesn't have the theoretical maximum bandwidth of HDMI although right now the average movie's HD audio plays no higher than a CD bitrate (705.5kbps/channel). Dark Knight and Letters of Iwo Jima for example play around around 1.5mbps which is (250kbps/channel). Some of the newer movies average around 3mbps which is 500kbps...

So really we are talking about no greater than multichannel CD bandwidth here (typically much less). Toslink/Optical can easily meet these demands. But in the future, who knows?

 

[Rubycon]

In this case, the copper has more bandwidth. Remember the "fiber" in toslink is plastic

Glass vs. plastic is not the issue. The issue that causes limits in bandwidth (and errors!) is the conversion on both ends. Remember a digital signal must be converted to light THEN on the receiving side it gets converted back to an electrical signal. With coax there is no conversion.

The use of higher quality transceivers and laser diodes would increase bandwidth and range tremendously. Optical SPDIF was never designed for this.

 

[sdifox]

Glass vs. plastic is not the issue. The issue that causes limits in bandwidth (and errors!) is the conversion on both ends. Remember a digital signal must be converted to light THEN on the receiving side it gets converted back to an electrical signal. With coax there is no conversion.

The use of higher quality transceivers and laser diodes would increase bandwidth and range tremendously. Optical SPDIF was never designed for this.

fair enough. I guess I should have mentioned the crappy transceivers involved.