JARGON BUSTER: Blu-ray and high definition explained

Baffled by all the technical jargon surrounding Blu-ray and high-definition formats? Don't panic, our Jargon Buster will help you understand what it all means...


Film's native frame rate. Film is shot at 24fps (frames per second of picture), and is played back in cinemas at the same rate. Video, on the other hand, is shot and played back at either 25fps (UK) or 30fps (USA and Japan).

That means film has to be converted to 25fps or 30fps for transfer to DVD, which can be done either by speeding up the footage (25fps), or repeating some frames (30fps).

However, on Blu-ray, video is stored at its native 24fps rate, ensuring a much more film-like experience. TVs that can't display 24fps try to convert the signal to another format (usually 30fps), which can result in motion problems.


The proportions of a screen or image - a ratio of width to height. The widescreen 16:9 (1.78:1) screen shape is used on most modern TVs and DVDs. Many cinema films are made in an even-wider 21:9 (2.35:1) shape, so your picture will still have black bars on a widescreen TV.

How The West Was Won was shot in the ultra-wide Cinerama format of 2.59:1. The image was so wide that it had to be projected onto a huge 146-degree curved screen from three separate projectors. However, most Blu-rays are made in either 1.85:1 or 2.35:1 shapes, which widescreen TVs will have no trouble in dealing with.


A Blu-ray feature that lets you access extra features online. Through your Blu-ray disc menu – and Ethernet connection – you can check out additional features, such as games and bonus film extras.


The measure of the quality of an audio or video file, in unit of bits per second. The bit-rate (in bits or bps) is measured with a prefix, such as kilo- (Kbits), mega- (Mbits), giga- (Gbits) or tera- (Tbits).

In terms of quality, the higher the rate the better. DVD's maximum is 5Mbit. Blu-ray's a maximum of 40 (and the now-defunct HD DVD is 29.5).


A loss of definition and visible blocks of pixels during fast-moving scenes. A spin of Transformers may illustrate the point – however, the problem is less common nowadays, but it's still sometimes seen when the TV can't keep up with the source signal.


Blu-ray discs (BDs) can store five times more information than DVDs, offering 25GB for single-layer discs and 50GB for dual-layer discs.

It's so called because a violet-blue laser is used to read and write data. This laser is far more focused than the red laser used on CDs and DVDs, which enables BD discs to pack in far more digital data than their same-sized forebears.


When TV pixels aren't quick enough to respond to fast signal changes. Very similar to Smearing, blurring occurs when your TV's pixels are too slow in reacting to rapid changes in the signal they're sent. It will sacrifice definition, detail and depth of field. Plasma sets tend to be less afflicted by this problem.


Every television and projector review will give an opinion of that product's ability to reproduce colours accurately, assuming it has been set up properly (see whathifi.com/video). Some sets might be described as being muted, while others can have overblown colours.


The amount of variation between black and white levels. Poor contrast used to be a problem with flatscreen displays, and can still be a problem with poorer TVs, but on the whole, most modern sets are strong in this area – plasmas more than LCDs. A lack of contrast can mask detail in darker areas, such as in scenes from the sepia-tinted epic 300.


The subtler bits of sound in a soundtrack. Ever wondered what a soundtrack really consists of? Most of it is made up of a complex web of instruments, voices, double-tracked parts, ensemble arrangements and massed vocals.

All these sounds are rich in detail: the crunch of boots on gravel or the scrape of a pick or bow on strings. Listen out for these nuances – they should be clearly audible – and you'll know just how good your AV system is.


The Digital Living Network Alliance is a set of open standards adopted by consumer-electronics manufacturers to enable their kit to share media such as photos, music and video.

For example, you could share a playlist on your Windows Media-enabled PC with your TV – which would show the track data, album art and so on. Alternatively, you could send the music to your DLNA-enabled AV receiver, which would then play through your hi-fi speakers. It's like Apple TV, for free (but less slick).


Digital light processing is a projector technology that's named for its ability to process light digitally with the aid of an optical semiconductor called a Digital Micromirror Device or DMD chip. DLP is usually superior to the rival LCD technology.


The relationship between loud and quiet sounds. Listen to a film soundtrack. Inevitably, some bits will be louder and others quieter. These are dynamics. The greater an AV system's dynamic ability, the more clearly you will hear the difference between loud and quiet – including the tiniest subtleties we call 'microdynamics'.


Ethernet is the widely installed local area network (LAN) technology – basically, a computer network covering a small area, such as a home or office. Specified in a standard IEEE 802.3 (the IEEE stands for Institute of Electrical and Electronics Engineers), the network typically uses coaxial cable. Ethernet is also used in a wireless LAN – commonly termed wireless fidelity, or just Wi-fi – and is specified at IEEE 802.11.


Full high-definition, or 1080p. In theory, the latest 1080p version of high-def video (with 'p' for 'progressive scan, where every line of picture is delivered in one signal) is better than older 1080i('i' for interlaced, as used by HDTV broadcasters), but it's not a hard-and-fast rule.

The resolution is 1920 x1080 pixels in 16:9 format (see Aspect ratio), and the picture is displayed in one picture 'pass' for each individual frame. This should mean a better image than 1080i, which interlaces the lines – rendering the screen in two passes per frame.


Audio as the director intended it to be heard. Provided you've the right kit, film soundtracks will leap out at you in all their multichannel glory.

Common formats include DTS-HD Master Audio, Dolby TrueHD and uncompressed PCM. A good AV receiver will be able to accept and replay all of these formats from your Blu-ray player.


High-Definition Multimedia Interface.The Scart cable for the digital age: a high-quality digital video/audio connection from source components to displays. The latest version, HDMI 1.3, can handle HD Audio formats.


HD-ready sets have a minimum horizontal resolution of 720 lines, and can handle both 720p and 1080i high-definition video (as found on, say, Sky HD). You'll find some variation in the overall resolution figure in HD-ready sets: most plasmas are 1024 x 768, while most LCDs are 1366 x 768 designs.

Full HD sets, on the other hand, have far more pixels: 1920 x 1080, or over two million. This is the same resolution as used on Blu-ray discs.


Stands for pulse-code modulation, or, in English, uncompressed digital audio. It's the purest encoding method - there's no loss in quality, but the file sizes are well into hyper-huge territory.

For example, for a three-hour film a multichannel PCM soundtrack could require a whopping 12GB. PCM audio is found on many Blu-ray discs, either in its native form, or repackaged (digitally 'zipped'), still at high quality, using a lossless system such as Dolby TrueHD or DTS-HD Master Audio.


Basically, fuzzy areas in the image. This has nothing to do with sound. Rather, it refers to faint speckling that's commonly visible on large areas of a single colour.


The percussive quality to a sudden sound. If done right, it'll sound sharp and weighty, almost like a push in the gut. Punch relies on a system being able to react quickly to sudden changes in dynamics, reproducing the sound without lag or flabbiness.


Like Blurring, smearing's caused by fast motion. When the pixels don't react quickly enough, it appears as if fast-moving objects have a vapour trail streaming out behind them.


Moving audio around in a soundstage. When you're listening to a 5.1 system, it will 'steer' sounds around the space in between the speakers – so, for example, cars will seem to race around you from left to right, or spaceships will scream from the back to the front of your room. The more speakers, the greater the scope for steering.


The relationship between the distance of the projector from the screen and the image size produced. Throw ratio is key to getting the right location for a projector.

In the device's manual, 'throw' might be expressed either as a ratio of, for example, 1.8:1 – meaning 1.8ft of throw per foot of screen width (ie, for a 10ft screen width, the projector must be 18 feet away); or throw distance – 9ft of throw distance to get a 60inch wide image.

For a projector with a zoom lens, the image size can be changed without adjusting the throw, or the size can be the same even if the throw is changed.


A quality-assurance standard developed by LucasFilm. THX is a set of rules for home cinema gear that should ensure a certain quality of cinema and home cinema sound.

Even if you don't have a cutting-edge THX set-up, the THX Optimizer test disc will calibrate colour, tint, contrast and sharpness, as well as check speaker settings, phase and crossovers on your 5.1 surround system. See our special THX Optimizer blog to discover how to use it.


Converting lower-resolution content into a signal that the TV will treat as HD. This can be done in the TV itself, or in the DVD player or AV receiver.

Results vary, depending on the quality of the processing hardware. Don't be fooled, though – converting a standard DVD picture to, say, 1080i doesn't mean it's suddenly as good as an HD picture.

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Andy Clough

Andy is Global Brand Director of What Hi-Fi? and has been a technology journalist for 30 years. During that time he has covered everything from VHS and Betamax, MiniDisc and DCC to CDi, Laserdisc and 3D TV, and any number of other formats that have come and gone. He loves nothing better than a good old format war. Andy edited several hi-fi and home cinema magazines before relaunching whathifi.com in 2008 and helping turn it into the global success it is today. When not listening to music or watching TV, he spends far too much of his time reading about cars he can't afford to buy.