Why not HDMI all the way?

[djcruiser]

Here is a question I have been wondering for a long time...

If HDMi cable is supposed to support the best picture and sound quality out the for any HD signal, then, Why don't they use HDMi from the starting point to the finishing point?

Meaning since I have DirectTV, why don't they run all of the wiring from the dish itself, down to the reciever boxes via HDMI? Same with Cable...Why not run all of the wiring for the Fios or Cable originating point to the cable box in the house?

I know with cable they would have to replace millions of miles of underground and above ground cables! But forget that that is an issue, and it was either cheap or free to replace it all!

I guess what I am getting at is this, If they can use RG-6 cable to our boxes, supplying the HD to the box, then why do we have to use HDMI cables to get the "Best Picture" and "Sound" out of said box? Aren't we getting the same signal from both in essence?

[acritzer]

Without knowing all the technical issues involved, I'd probably just guess that it has something to do with what the receiver box is actually doing. The box is processing the signal.

[jdc115]

Originally Posted by djcruiser

Here is a question I have been wondering for a long time...

If HDMi cable is supposed to support the best picture and sound quality out the for any HD signal, then, Why don't they use HDMi from the starting point to the finishing point?

I am not sure if your assumption is correct about best picture and sound to start with, there maybe many better solutions then HDMI. But maybe HDMI serves a specific purpose in end user applications.

But assuming it is the best, I would assume it costs too much for one thing. The other is HDMI seems limited in its ability for long runs. But maybe that has something to do with the type of signal being run over it or the bandwidth demand, i am not sure.

[Pelican170]

I would assume because the signal isnt digital until your box converts it to a digital signal.

[djcruiser]

Thanks for the answers so far...

I would also be curious as to why we couldn't use RG-6 cable the whole way?

Either/Or?

Why both? Cable to the box, HDMI from the box?

I do know that the higher codecs for audio are only acheived via HDMi, but is picture quality for HD really that dependent on HDMI or could RG-6 Cable or A/V component cables be just as good of quality?

Maybe it is me not trusting business's some much as to thinking that they are manufacturing the quality factors to get consumers to spend more money when the don't really need to.

[Pelican170]

Originally Posted by djcruiser

Thanks for the answers so far...

I would also be curious as to why we couldn't use RG-6 cable the whole way?

Either/Or?

Why both? Cable to the box, HDMI from the box?

I do know that the higher codecs for audio are only acheived via HDMi, but is picture quality for HD really that dependent on HDMI or could RG-6 Cable or A/V component cables be just as good of quality?

Maybe it is me not trusting business's some much as to thinking that they are manufacturing the quality factors to get consumers to spend more money when the don't really need to.

Well, the new audio codecs can be used with analogs instead of HDMI. and Component cables offer the same quality as HDMI, but most sets dont accept the signal over Component inputs.

[D1-2005]

I would assume the biggest reason is digital copy protection, HDCP.

[Trix]

Originally Posted by djcruiser

Thanks for the answers so far...

I would also be curious as to why we couldn't use RG-6 cable the whole way?

Either/Or?

Why both? Cable to the box, HDMI from the box?

I do know that the higher codecs for audio are only acheived via HDMi, but is picture quality for HD really that dependent on HDMI or could RG-6 Cable or A/V component cables be just as good of quality?

Maybe it is me not trusting business's some much as to thinking that they are manufacturing the quality factors to get consumers to spend more money when the don't really need to.

First, for the HDMI vs. RG-6. When the signal comes from a satellite, or from a cable jack in your house, the information is packed and encoded in a way that your television could not decode, at least for HD channels. (As a sidenote, for over-the-air HD, RG-6 will carry HD video from the antenna to the TV, but this is because the decoding is done in the TV itself if it has an OTA-HD tuner. If it does not, the digital converter will need HD outputs for HD channels.) Once the signal is converted from its data packets to HD programming, outputting through RG-6 from the cable box will get you 480i programming. Is this because manufacturer's won't allow HD over RG-6? Maybe, but given that an RG-6 cable is a single tranmission line with a ground, it would seem as though it is in fact limited.

The question of "why not use HDMI the whole way" is parallel to asking "why doesn't my internet come into my house on a Cat-6 cable, straight from the internet company?" Essentially, as mentionned earlier, transmission through your cable or satellite RG-6 lines is data packets that travel fine through RG-6. HDMI, High-Definition Multimedia Interface, is just that, and interface meant to facilitate the transmission of HD multimedia from a source to a display, not across a network. Do you also wonder how it is that the phones lines that circulate in a neighbourhood also look in no way line the phone lines in your walls or from your wall jacks to your phone?

And finally, the lovely question of whether or not HDMI is the new divine intervention. I'm not at all looking to argue over this, so I will try to state basic facts. Let's compare first to composite video, your lovely yellow cable with RCA ends. Strictly speaking, there is absolutely no way to get a resolution higher than 480i (576i for PAL, I believe) simply because it is a single cable, again with a single conductor and a ground. If you recall, when progressive scan DVD players came out, composite video cables could not even carry 480p because of their limited bandwidth. Enter component cables, green, blue, and red cables with RCA connectors. Essentially, three cables each capable of doing the job of one composite cable. So, you triple your bandwidth. With unprotected content, component cables can carry resolutions up to 1080p; HDCP-flagged content will not transmit beyond 1080i through component, to protect it from being recorded.

Now, as I've mentionned, yes component cables are able to handle 1080i signals, which covers every broadcast and satellite channel. So, then, do you need HDMI? No, not at all. What's the difference? Essentially, in transmission; with HDMI cabling, you have a digital signal in your cable/satellite box, transmitted digitally through the cable, and displayed digitally on the television. With component cables, the digital signal in your satellite/cable box is transformed into three analog signals, transmitted over an analog medium to the television, which, being a digital display, re-digitizes it for display. Is this a huge, mind-blowing difference? No. Most televisions are able to handle the process flawlessly.

As I mentionned in the outset, however, I am not here to debate if there is a quality difference, however, because I don't personally have a strong opinion on the matter. I believe that HDMI in most applications is a matter of simplicity, with one cable instead of [at least] three.

[syncguy]

Good description. I would add few more points to complete the picture.

A video signal is transmitted in different ways over different mediums. At some stages a HD video signal is highly compressed with mpeg4 compression and some stages it is fully uncompressed and needs significantly higher bandwidth for transmission.

Signal path:
1. TV network to Antenna (or Cable feed) to the set-to-box: At this stage it is a highly compressed video signal digitally modulated over an analogue RF signal. The transmission medium is a coax cable with sufficient thickness to carry the RF signal. HDMI cannot carry this signal, it is a totally incompatible transmission system.

2. Once the signal is in the box, it would be uncompressed and will need significantly more bandwidth to transmit to the TV set. Coax cable cannot carry this uncompressed video signal. HDMI is specifically designed to carry high bandwidth 1080P uncompressed video signal over shorter distances (box to the TV set).

[djcruiser]

I thank everyone for the input.

Thanks for the detail also.

[Mahatma]

I jumping on the HDMI bandwagon.HDMI is completely digital isn't it?If so:Why do they sell the cables in different pricerange?I've seen cables at ridicilous prices ($300) for 2 meters.If using digital signals,a standard network cable is capable of transmitting 50 megabit per second easily,and they you get for about $10 for 5 meters-or there about.

Can someone explain this to me?Is this just hype,or are they using other transfer standard which doesn't use CRC?

[syncguy]

Originally Posted by Mahatma

I jumping on the HDMI bandwagon.HDMI is completely digital isn't it?If so:Why do they sell the cables in different pricerange?I've seen cables at ridicilous prices ($300) for 2 meters.If using digital signals,a standard network cable is capable of transmitting 50 megabit per second easily,and they you get for about $10 for 5 meters-or there about.

Can someone explain this to me?Is this just hype,or are they using other transfer standard which doesn't use CRC?

HDMI is digital so as 3G mobile. However, these digital signals are carried over analogue electrical signals (all physical electrical signals are analogue). These electrical signals degrade over the length of the cable. If the cable is thick and high quality, the physical signal degradation can be reduced. The possibility of "1" appearing as a "0" can be reduced.

[Hammie]

Actually optical would be far better than any copper cabling. I have worked with some customers who I believed used optical with their satellite deployment due to the higher frequency range capabilities. If memory serves me with coax, they were limited to around 2000MHz, but optical allowed them to get up to 10GHz on a single cable versus multiple coax cables to get the entire frequency range.

However, even with optical, you will still need a device that will decode the signal. So, the question is whether HDMI signalling will ever go over optical (DWDM can carry up to about 400Gbps of bandwidth) but now you adding more cost into the equation.

[syncguy]

Originally Posted by louhamilton

Actually optical would be far better than any copper cabling. I have worked with some customers who I believed used optical with their satellite deployment due to the higher frequency range capabilities. If memory serves me with coax, they were limited to around 2000MHz, but optical allowed them to get up to 10GHz on a single cable versus multiple coax cables to get the entire frequency range.

However, even with optical, you will still need a device that will decode the signal. So, the question is whether HDMI signalling will ever go over optical (DWDM can carry up to about 400Gbps of bandwidth) but now you adding more cost into the equation.

Optical is used to transport electrical signals over longer distances and it works as an extension. Optical extensions are tailored for different applications. e.g. HDMI optical extensions are available. Same way RF coax optical extensions are available.

If longer HDMI is needed, one may use an optical extension.