HDMI sockets are important for any new high-def television but, as usual, the devil is in the detail.
HDMI is the new cable format which combines high defintion audio and video into the one cable - reducing the wiring jungle behind your AV cabinet. If you're looking at a new television then consider HDMI inputs mandatory - the more the better.
HDMI 1.4
The HDMI standard is now up to version 1.4, although this was only standardised in May and HDMI 1.4-compatible products probably won't appear on the shelves until 2010. Meanwhile, you're more likely to find HDMI 1.3-compatible gear on the shelves.
Connecting a PC
One of the great things about HDMI is that it's compatible with the DVI sockets used on computing gear, so you can hook up your PC to your TV using a DVI to HDMI cable.
Factoring in audio
Unfortunately DVI doesn't carry audio, so you'll need to use a separate AV cable - probably a stereo 3.5mm to 2xRCA. If you intend to do this, it's very important to look for a television that has stereo RCA inputs alongside at least one of its HDMI inputs.
Manufacturers began working on the HDMI 1.0 format in 2002, combining 1080p video, 8 channel audio and Consumer Electronics Control (CEC) used to pass remote control commands between devices.
New versions of the HDMI format have increased the bandwidth and added other features, but thankfully they've remained backwards compatible. In a nutshell, the changes have been:
- HDMI 1.1 - support for DVD Audio
- HDMI 1.2 - support for Super Audio CDs
- HDMI 1.2a - full support for CEC
- HDMI 1.3 - support for higher resolutions such as WQXGA (2560×1600) and more colours used by Deep Colour (like the x.v.YCC format). Also support for lossless compressed audio streams Dolby TrueHD and DTS-HD Master Audio HDMI 1.3a - Updated list of CEC commands HDMI 1.3b - compliance testing revisions for 1.3a (no new features) HDMI 1.3c - compliance testing revisions for 1.3a (no new features)
- HDMI 1.4 will add support for higher video resolutions and Ethernet Channel for longer cable runs.
Which is best?
For your average punter there's not much difference between the HDMI formats, but if you've got a fancy surround sound system then you'll be interested in HDMI 1.3 because of the audio format support.
Coax and optical cables
Neither coax nor optical cables are suitable for high bandwidth Dolby Digital Plus, Dolby TrueHD, DTS-HD HR and DTS-HD Master Audio surround sound formats. Nor are coax or optical suitable for raw PCM 5.1 channel sound. If you use coax or optical cables, these high-end formats will be scaled back to Dolby Digital, DTS or two channel PCM.
Such high bandwidth audio formats should be carried via a HDMI cable, with HDMI 1.3-compatible equipment required if you want to send lossless compressed audio streams such Dolby TrueHD and DTS-HD Master Audio to your home threatre amplifier.
If you've got an older version of HDMI, you'll need to decode such formats on the source device and send uncompressed multi-channel PCM audio stream to the amplifier.
Buying a flat screen TV? Have a question you'd like us to answer? Add your comments or questions about flat screen TV issues to the discussion below.
Also in this series, How to Pick a Great Flat Screen TV, And Not Get Sucked In By Marketing Hype:
Part 17: Will 2010 be the year of OLED?
Part 16: Super-thin TVs come at a price
Part 15: How big a TV is too big?
Part 14: Should I care about refresh rates?
Part 13: How do I compare HDTVs in the store?
Part 12: Hiding your television
Part 11: calibrating your television
Part 10: those pesky upscaling issues explained
Part 9: video inputs and future proofing
Part 8: Logitech Harmony vs AV Link remote controls
Part 7: Should you upgrade your TV for DLNA?
Part 6: TV tuners and "Digital Capable"
Part 5: HDMI and component ports
Part 4: LED and backlighting
Part 3: Screen size
Part 2: Refresh rates
Part 1: Brightness and contrast ratios
Also see our 5 tips for buying a digital TV set top box
And also see the lowdown on Freeview, and whether you should care
If you're new to Digital TV, or have yet to make the leap, start by reading Prepare yourself for Digital TV