Here with some cut and paste from HDMI training literature...

High Definition Multimedia Interface, or HDMI, as it’s name suggests, is an interface that can carry more than one type of media - namely audio and video, and is able to carry these at high bandwidths - in other words, lots of data in a short period of time.

The first thing to understand about HDMI is that it, itself, does not make images or sounds better, but simply that it has the potential to carry high quality audio and video. It is entirely possible to transfer a low quality image and low quality sound using an HDMI cable, just as it is also possible to carry high quality images and sound using other transfer methods such as component or optical connections.

HDMI has several benefits to both manufacturers and consumers...

Only one cable is required to carry picture and sound between compatible devices:

As mentioned above, HDMI can carry both audio and video. This requires both the sending and receiving device to support this.

Content which is subject to copyright can be transferred in it’s native resolution:

HDMI devices must support a copy protection system called HDCP, which is explained in further detail in this guide. This has enabled film companies and record labels to release films in high definition picture quality without risking it being copied and distributed illegally.

Image scaling can be applied to copy protected content:

The HDCP system has also meant that manufacturers can now allow products to improve standard definition images which are protected by copyright. This is called image scaling and is not allowed from copy protected sources (such as DVD) unless the scaled output is still protected - HDMI with HDCP allows this and prevents unlawful copying and distribution.

As HDMI is so new many consumers hear some information from one person, read another bit of information (which is often written by other people who are not fully literate about the technology) and tend to fill in the blanks as they think equipment will operate. This leads to information being spread by word of mouth which is often incorrect. Here are some popular misconceptions about HDMI...

HDMI will give a better picture:

HDMI is just a connection type, the image quality will depend on the content and the products being used to send and display the image. Don’t forget - HDMI does not mean high definition, it can be standard definition too!

HDMI is always able to carry audio and video:

HDMI can carry audio and video, but again only if the source and receiving device support this. HDMI is only able to transfer the data that is sent by the source.

AV amps equipped with HDMI will scale video:

Scaling is a totally separate process and an amp with HDMI may scale or may not.

AV amps equipped with HDMI will convert non HDMI inputs to an HDMI output:

Again, just having HDMI does not mean that an amp can convert other video input to an HDMI output. This function is available on some HDMI amps but not on others.

A device with HDMI will be superior to one without:

HDMI can be a benefit on products, but high quality devices do still exist without HDMI, just as poor devices do exist with it.

HDMI cables are all the same:

HDMI cables are available in different qualities. These will, just as other cables do, vary the quality of the passing signal. Some cables can carry high bandwidth data over a greater distance than others as a consequence of this degradation.

HDMI can carry both standard definition and high definition images:

Both standard definition and high definition data can be carried by HDMI, again, only if the source and receiving device support this.

HDMI can carry any type of video signal:

An HDMI device should be able to support picture resolutions of 480p, 576p, 1080i and 720p - it is not required to carry 480i or 576i, again this is dependant of the connected equipment. Some devices can now support 1080p.

HDMI Versions...

There are currently (March 2007) five versions of HDMI that have been finalised. Three versions have now been superseded, one is current, and one is not yet launched but the standard has been agreed and finalised. Please remember that the HDMI version is specific to the device, not the cable being used, and when connecting two devices together, all versions are backwards compatible but only the lowest version will be able to be used - ie, if two devices are connected, one is version 1.2a and one is version 1.0, both devices will behave as if they both had version 1.0.

HDMI version 1.0:

This version of HDMI supports only video data. A device that supports HDMI version 1.0 can never accept or send audio data, regardless of the device to which it is connected.

HDMI version 1.1:

In this version, audio is also supported as well as video. Audio comes in many different types - HDMI version 1.1 supports PCM, AC3 (known as Dolby Digital), DTS and MLP Lossless (Audio DVD audio).

HDMI version 1.2:

This version is as version 1.1 but adds an additional audio type - DSD (Super Audio CD data). It also adds support for PC video display resolutions.

HDMI version 1.2a:

No extra information can be carried but there are more finalised Consumer Electronic Control (CEC) features and command sets. There are also options for a manufacturer to submit new cable lengths or connector designs, which must be approved by the HDMI Compliance Testing Specifications (CTS) - before it can be used.

HDMI version 1.3:

Version 1.3 has recently been finalised and should be on production devices in mid 2007.It can carry extra audio types - known collectively ad high definition audio. These are Dolby Digital Plus, Dolby TrueHD, DTS HD and DTS Master Audio. In addition to these extra audio types, HDMI 1.3 has the capacity to carry more colours (deeper colour space) and carry more information due to it’s potentially higher speed transfer rate. This will allow future devices (when available in several years time) to use higher frame rates and resolutions to achieve even higher definition images. It also has the potential to automatically correct lip-sync errors caused by video processing in fixed pixel displays such as Plasma, LCD or projectors.

I think that will do for now, if you want the full article right down to the wiring spec let me know and I will send it to you courtesy of Yamaha UK...

Regards Rab Turner