High Definition Home Theatre

Today is an exciting time to be a home cinema fan. With the advent of high-definition home video and audio, it is now possible to view films at home that will look and sound at least as good as they did in the cinema. To achieve this, you will need to make sure your home cinema setup meets the requirements of reading, converting and displaying a high-def source.

To begin with, you will need a hi-def source. Many cable and satellite packages offer hi-def channels, but many channels use large amounts of compression to squeeze multiple high-def channels into a limited amount of bandwidth. This causes images to have compression artefacts, such as macro blocking, mosquito noise or banding. Audio can also be affected, with very low or high frequencies clipped and complex parts of the soundtrack sounding "muddy".

The same problem is present on the new "download" services that allow you to download and watch a film for a fixed price. Although less noticeable, the problems of compression are still visible. Lastly, some DVD players will provide "up-scaling" of standard DVD's, and while this can be an improvement on letting your TV upscale the image, it's not a true high-definition signal, and will appear soft and blurred.

The best source for Hi-Definition content is from a Blu-Ray disc, where there is enough space to store the image without introducing noticeable compression artefacts, and to hold completely lossless sound. Look for a player with an internet connection for easy updates to the firmware, or alternatively consider a Sony Playstation 3 console, which is also a very high-quality Blu-Ray player.

With a hi-def system, only one cable, HDMI, is required to transmit both picture and sound. A HDMI cable is a digital connection, so there are fewer problems from noise or interference. Beware overpriced cables; the digital signal means expensive multi-layered insulation is not necessary. Pay no more than you would for good computer DVI cable, on which the HDMI standard is based.

The hi-def signal will first go into your home-cinema amplifier, which will need a HDMI input. The amplifier needs to be capable of decoding the sound formats used by the Blu-Ray disc. The most common formats are Dolby Digital Plus and DTS-HD, these are updates of the formats used on DVD's, and all modern home cinema amps should decode them. Look out for Dolby True HD and DTS-HD Master Audio support, these are new formats for maximum-quality lossless sound, but only the latest or more expensive amps have support for these right now. Lastly you may see LPCM audio tracks. These are lossless and uncompressed, so no decoding is required and all amps can play them.

Your amp should have a HDMI output that will allow you to connect it to your TV or Projector. With the amp handling the audio, the video signal is fed back out and into your display. To properly function your display will need to be "HDCP compliant", HDCP stands for HD "Copy Protection", and only HDMI inputs with the built in HDCP technology can decode HD video. All newer displays have this, but some early TV's and projectors had HDMI sockets that missed out the HDCP chip.

There are several different resolutions that can be called High Definition. 720p and 1080i are used by some TV channels and also hi-def video games. The highest standard is 1080p, and is used by Blu-Ray movies. Most new displays will handle all three formats, but when buying a TV or projector, check the native resolution, the number of physical lines of picture it can display. TV's that only have a native resolution of 720 will be forced to scale a 1080p signal down, which will reduce the picture detail and may introduce artefacts.