6. Cables of yesterday won't work today; cables of today won't work tomorrow – so choose wisely!
The objective of High Definition digital video is to display, as realistically as possible, the depth of colour, motion, contrast, sharpness and detail that the human eye sees in real life. It's a bit of a stretch to say that technology is getting close, however, advances are steadily being made every day.
While technology continues to advance at a rapid rate, High Definition as we know it today (720p/1080i) is relatively low bandwidth. With new displays that increase sharpness and resolution from 1080i from 1080p, the scan lines are doubled. Therefore the data that has to be transferred to the screen every second is doubled – from 2.2 Gbps to 4.46 Gbps. Double the previous data rate per second means cables that worked for 1080i, may not work for 1080p – especially over longer lengths.
To get even better colour, the technology is coming to provide "deep colour". Today's standard is 8-bit colour, but Blu-ray and HD DVD feature 12 and 16-bit colour, increasing the data rate again to 6.6 Gbps and 8.8 Gbps respectively. In order to provide "smoother video" which becomes important for fast action, we will see displays with higher refresh rates. The refresh rates of displays will go up this year from 60 times a second (60Hz) to 90Hz and 120Hz, increasing the data rate again to 12.2 Gbps.
To make matters even more demanding, future TVs will have even more pixels than 1080p – 1440p and more – as consumers demand ever-bigger, brighter, sharper pictures. The data rate increases as the pixel count increases. These displays are already available for computers and professional grade projectors.
The conclusion is that HDMI cables that work today may not work tomorrow. HDMI cable technology is a bargain considering the cable performance of just a few years ago. Since the cable is probably the least expensive component in a home theatre system, it pays to purchase the best possible cable that current technology allows. With any long run of HDMI cable, quality manufactured cables play a significant role in successfully running HDMI over longer distances. Signal relays and boosters can help, but as with any cable choice, quality has a significant effect on performance.