# Why aren't optical cables used for video and everything else digital?



## nrnoble (Aug 25, 2004)

I looking get a better understanding of optical cables

My limited understanding of fiber optic technology is that it has the ability to support a huge bandwidth, allowing an entire cable system to carry all its channels, high speed internet, and phone.

Q1 Are "optical cables" that are used for digital audio in home AV system the same thing as "fiber optics"?

Q2 Why couldn't optical cables also be used to carry "digital" video signals between AV systems and connected components such as DVD players and TiVo S3. (understanding that the hardware would have to first support it)?


I am asking because I am truly curious, but there is a practical reason, I have way too many flipping cables connecting everything up. Ideally, I would love to have one cable between any two devices\components that handled EVERYTHING (data, video, audio, etc). Connect up a DVD player, use 1 cable. Connect up a TiVo, use 1 cable, connect up HDTV, use one cable, etc, etc. It seems that a single optical cable has the band width if everything between devices is digital. I understand that optical technology doesn't support analog signals unless they are digitized.

Thanks


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## captain_video (Mar 1, 2002)

Optical cables are indeed fiber optic cables. There is currently no consumer standard in place for transmitting digital video signals over a fiber optic connection. In fact, the fiber optic connection will eventually be superceded by latest HDMI standard, at least in theory. In reality, fiber optic will be with us for quite some time since it allows more flexibility with most existing electronics. HDMI 1.3 allows for the transmission of both digital video and digital audio and supports the latest digital audio formats that are part of the Blu-Ray/HD-DVD standards. 

There aren't many components that utilize the 1.3 standard yet and it will take quite some time to reach high market penetration. That was once true for USB devices for your PC when it was first introduced and now everything is USB.

Fiber optic cables and coaxial digital cables both carry the same audio signals and many consumer devices support both types of connections. The fiber optic connection, or Toslink as it is more commonly known, seems to be more popular than the coax connection but many audio enthusiasts prefer the coax over the Toslink for better quality. At least that's the report on the street so YMMV.


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## classicsat (Feb 18, 2004)

A number of factors, mostly based on price/complexity for the bandwidth.

Optical audio, I believe uses plastic. Communications grade fibre is glass.
The cost of the gear to mux video on one circuit, and modulate it over light, and go the other way, is likely too expensive to consider for consumer equipment.

Copper is cheap anyways, and works.


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## stevel (Aug 23, 2000)

See this article on a recent Intel announcement of optical cables that swap in for existing copper cables. While this is for computers, the technology could be used for video and audio as well.


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## Chibbie (Jan 16, 2006)

nrnoble said:


> deally, I would love to have one cable between any two devices\components that handled EVERYTHING (data, video, audio, etc).


Isn't that basically what the HDMI cable is for?

However, I think eventually we will need an optical version of the HDMI cable. There was a big discussion on Gizmodo about the quality of HDMI cables , and whether it was worth it to get Monster Cable vs. generic. The bottom line was, for short lengths generic is fine, but after 6 feet or so it starts to make a difference in the signal. And the higher the picture quality, i.e. 1080p and beyond, the bigger the difference.


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## Dan203 (Apr 17, 2000)

The simple answer is cost. Optical cables cost more to make, and the electronics used to convert a signal to and from light are more expensive. So until we hit a point where the data coming out of our devices is too much for a copper wire to carry we'll be sticking with copper.

Actually the next step is most likely wireless. There are several wireless technologies on the horizon that are aiming to eliminate the cables between devices completely. If those ever become a reality then we'll never have to worry about cables again. 

Dan


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## jlb (Dec 13, 2001)

We're not that far off:










http://www.engadgethd.com/2007/01/08/philips-intros-wireless-hdmi/

From the secondary link in the endgadget story:



> Wireless HDMI (yes, version 1.3 supported) device announced, the world's first "and only" solution for transmitting uncompressed HDMI over the air. It works at a range of about 25 feet -- short range cable replacement solution folks. They achieve 1080p lossless transmission without interference due to operation in the UWB frequency spectrum. No release date, maybe Q3, no pricing. Will be offered in a couple of flavors: single-input and multi-input.


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## steve614 (May 1, 2006)

Dan203 said:


> Actually the next step is most likely wireless. There are several wireless technologies on the horizon that are aiming to eliminate the cables between devices completely. If those ever become a reality then we'll never have to worry about cables again.
> 
> Dan


Ugh. Yet another wireless device that I have to worry about channel crossover.


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## Dan203 (Apr 17, 2000)

Actually they use much lower frequencies then current wireless technology. That's what gives them their massive throughput. It's also what limits their range to 20-30 feet and requires them to have line of sight from transmitter to receiver.

Edit: Actually I just read some more on that Philips product and it doe NOT require line of sight. So that's cool. I have a bed room which is directly over my living room. I wonder if I could use this to transmit HDMI from the living room to the bedroom through the floor. That would be awesome if I could. 

Dan


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## painkiller (Jun 23, 2005)

There is another facet as to why fiber optics isn't catching on as much as HDMI.
As I see it, this is even more important to the media companies than it is to us.

DRM. Digital Rights Management.

The HDMI embodies the integration of video and audio at both ends of the HDMI connections within the devices such as DVD players and monitors and A/V receivers.

It 'guarantees' an uncopyable media stream.

According to the MPAA and hardware industries that have a lot invested in this technology.

They prefer that the use of fiber optics wont be used until equivalent DRM protection standards are put in place for such high bandwidth conduits.

Until such time, for now it is HDMI cables.


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## sfhub (Jan 6, 2007)

painkiller said:


> There is another facet as to why fiber optics isn't catching on as much as HDMI.


Umm, why wouldn't they just run HDMI/HDCP over optical instead of reinventing the wheel? HDMI over fiber already exists.


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## musika (Jun 29, 2007)

yeah optical makes more cost to make..


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## ewilts (Feb 26, 2002)

nrnoble said:


> Q2 Why couldn't optical cables also be used to carry "digital" video signals between AV systems and connected components such as DVD players and TiVo S3. (understanding that the hardware would have to first support it)?


I work with Fibre Channel hardware for a living so I have some experience here. A typical 4Gbps fibre channel adapter for a PCI-X bus will run you in the $850 range. A single SFP (Small Form Pluggable) transceiver which has just the optics on a switch lists around $200.

Fibre Channel stuff is fast and reliable, but it's awfully expensive. Optics also fail more often than copper and special attention needs to be paid to the running of the cables - you can't do a nice tight coil on the floor like you can with copper and you can't drop your UPS or TiVo on it and still expect it to work.

Really low-end optical connectivity might be doable and cheap like it is for the S3, but in general, you do optical because you have to, not because you want to.

.../Ed


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## Neiko-MN (May 14, 2004)

Chibbie said:


> Isn't that basically what the HDMI cable is for?
> 
> However, I think eventually we will need an optical version of the HDMI cable. There was a big discussion on Gizmodo about the quality of HDMI cables , and whether it was worth it to get Monster Cable vs. generic. The bottom line was, for short lengths generic is fine, but after 6 feet or so it starts to make a difference in the signal. And the higher the picture quality, i.e. 1080p and beyond, the bigger the difference.


Yes, Monster Cables are horribly overpriced. For some very in-depth discussion re: HDMI cables see the Blue Jeans Cable custom made Belden HDMI cable update. They also sell "generic" HDMI Cables that they have tested to 50 feet.

BJC also has a host of articles about cable quality, issues with HDMI, etc...


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