Special Report: HDMI 1.3
HDMI, an integrated digital connection for uncompressed video and audio, was launched in December 2000 by a consortium including Hitachi, Panasonic, Philips, Silicon Image, Sony, Thomson and Toshiba. It is the new connector positioned as the HD replacement for SCART appearing on A/V equipment designed for HD connections. It is also likely to start replacing VGA and DVI connections on desktop PCs and laptops.
The technology is now on its fourth revision. Version 1 offered a maximum capability of 1080p60 resolution and 24bit RGB colour with 8 channels of uncompressed audio at 192kHz - even though there were no consumer devices that supported those standards at that time. Version 1.1 added support for DVD-Audio and 1.2 added support for SACD and low power output computer monitors.
1.2a added enhanced consumer functionality with the "one touch play" ability to control all machines from any device. It also increased cable lengths and, after some connectors started fallng out, the robustness of the connector was improved.
The new 1.3 iteration of the interface doubles the bandwidth from 4.95Gbps (165MHz) to 10.2Gbps (340MHz) – and still offers the capability of dual link connections. It also offers the ability to support 1440p (WQXGA – 1440x2560) which is the next step up from 1080p and also offers refresh rates up to 120Hz (something that may be supported on the PS3 which is committed to support HDMI 1.3).
HDMI adds support for something called “Deep Colour” which is a capability to support 30/36/48bit colour depth. Screens supporting this are likely to appear next year; Sony demonstrated one earlier this year at CES. The final visual addition is something called the “xvYCC” colour space. The current colour space that is used by SD and HDTV cameras and display devices only displays about 60% of all the colours that are possible, but the new “xvYCC” colour space has 1.8 times as many colours available and so produces a more realistic rendition of colour. However, this will take some time to filter through to consumer availability because the new colour space will need to be supported at every step in the delivery chain.
On the audio side HDMI 1.3 adds support for Dolby True HD and DTS HD, both uncompressed multi track master audio formats. It also offers a function called "Automatic Lip Sync Timing Compensation" which knows how long each element of device takes to process the audio and video and so can automatically add the appropriate amount of delay to the audio so that there is perfect lip sync.
The final addition provided by 1.3 is a small format plug/socket for the use of camcorders, digital still cameras and other portable devices.
One of the interesting things about the HDMI standard is that it is a standard created by manufacturers and supported by licence agreements so there is a great deal of flexibility in what needs to be supported. Not every device has to support every element of the standard so you don’t have to have a small connector to be 1.3-compatible. Two HDMI devices will be able to talk to each other to discover what they can do and what highest level of support each device is capable of.
In the US, HDMI is being sold as the solution to the spaghetti of cables behind most TVs; of course, here in Europe we know that having a single cable solution (SCART) just reduces not removes that pile of wires behind the TV.
HDMI is an extension to the DVI standard found on many PC video cards, which is why you just need a passive connector to convert between HDMI and DVI. The reality is that because the connector is more compact there is now a real likelihood of seeing the HDMI move towards the PC arena as it is a smaller, lower cost solution for manufacturers with the added bonus of more functionality, especially on laptops. Laptops with blu-ray players are likely to become available and with a HDMI connection it would be easy to hook it up to an existing A/V setup.
One thing that HDMI does not offer is a solution for transmitting data for recording. HDMI is an uncompressed data format for display and is not designed or positioned as a way of getting data to a recording device. The 4 letters most associated with HDMI are HDCP - High-Bandwidth Digital Content Protection. This is actually something that has nothing to do with the HDMI standard itself but is a copyright protection system implemented over the top of it by manufacturers and studios to protect their content. HDCP is designed to protect data and make it very hard to make digital copies of the uncompressed output. Of course at present there are no devices that record from the uncompressed data that HDMI provides and this leads to the one issue with HDMI. Currently there is a way to archive material via SCART but in the future that role is unlikely to be directly facilitated by HDMI so how archiving from an HD STB to a blu-ray recorder will work remains an unanswered question.
Sony have already been quoted as saying that HDMI 1.3 will be delivered on the PS3 and their quotes make heavy reference to the high speed capabilities (high refresh rates) and deep colour options. The PS3 will likely offer these capabilities even if there are very few people with screens to support them.
The HDMI consortium have a number of test facilities to allow manufacturers to test compatibility between devices to help reduce issues with items not correctly working; indeed, it is a requirement that things are checked. The latest 1.3 specification includes new specifications for cables and cable testing; there will be ones that are easier to use, such as flat cables, but the HDMI team points out that with digital signals cables meeting the same specification should perform the same. The team added that possible issues would be with the length of different strands of wire in the cables causing "timing differences between cable pairs" although if anything that is more likely to occur with thicker cables rather than thinner ones.
In conclusion, the 1.3 update keeps HDMI positioned as the connector of choice between A/V equipment for the foreseeable future and we can expect it to start appearing on everything from low cost DVD players, A/V amplifiers and TV screens to computer graphics cards and portables. Although there are other connectors out there trying for segments of the market HDMI seems to have a good lead. It is expected that there will be 60 million HDMI / DVI devices shipped this year and 125 million next year. There are still issues with compatibility between various HDMI devices but that is one of the problems with systems that are trying to be intelligent. Hopefully as time progresses testing procedures and interoperability will improve and these issues will become less apparent. Overall HDMI does offer the chance to make cabling up TVs a much simpler operation and that has to be a good thing.