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As in 3D television or 3D films. Essentially this refers to content that is designed to provide a three-dimensional image, meaning a picture will "come out" of the screen and provide extra depth for a more realistic viewing experience. TVs generally decode this information in two ways; Active 3D and Passive 3D (see below), which require the user to wear glasses. There have been some glasses-free 3D sets, but they're few and far between, require you to sit in a very specific position and are very expensive.
3D - active
One of the two ways that televisions create a 3D picture. Active 3D uses a process known as Alternate Frame Sequencing. The TV creates two images (one for the left eye, and one for the right) and flickers rapidly between the two. The glasses for this type of television are usually battery-powered and have shutters that open and close in time with the two images on the TV. Because this happens faster than the human eye can detect, the brain perceives a complete, three-dimensional image. The advantage of this format is a slightly sharper image. The main downside is the possibility of a slightly flickering image. For an alternative, see 3D - passive.
3D - passive
Passive 3D uses the same glasses as the majority of cinemas, giving them an instant advantage over active sets as, if you've ever seen a 3D flick, you've probably got some specs lying around. They also produce a more comfortable, flicker-free image. The trade-off is that the image in 3D is lower resolution than the active system; however, many people do still prefer it. The only way to know for sure is to pop in-store and have a peek.
4K, or Ultra High Definition, is the next evolution in enhanced resolution, for sharper images. 4K is so named because it has approximately 4000 pixels across (the exact number varies depending upon which camera the director chooses, but in the home you get 3840). The format gives approximately four times more detail overall than 1080p Full HD. 4K content is becoming more common too, with services such as Netflix and Amazon Prime offering movies and series on demand, plus over the air broadcasts and 4K Blu-ray.
Find out more here.
Also known as 'True HD' or 'Full HD', this is the first major bump up in image quality over standard TV broadcasts and DVD. The most common place to find 1080p is from a Blu-ray disc, although you need a 1080p screen to watch them in their full glory. The number '1080' represents the 1,080 lines of vertical resolution, progressively scanned (see entry). The term usually assumes a widescreen aspect ratio of 16:9, implying a horizontal resolution of 1920 pixels. This creates a frame resolution of 1920 x 1080, or 2,073,600 pixels in total.
AAC (Advanced Audio Coding)
A digital audio encoding system that compresses data files for greater storage capacity - think of the music tracks stored on an iPhone and you're on the right track. AAC is similar to MP3, but offers superior quality and DRM support (Digital Rights Management, to prevent illegal distribution). AAC is the preferred coding system of Apple, so, for example, you'll find tracks on iTunes encoded this way. A typical file's size is 4MB for a 3-minute song, but this varies depending on quality and track length. This format is great for those looking to fit a lot of music on a smaller capacity device. It was initially designed to replace MP3 as the format of choice.
AirPlay is the Apple technology that enables you to stream music, videos or photos from a compatible device to a speaker or screen. Any device running iOS (such as an iPod Touch, iPad or iPhone), or computers with iTunes installed can send content. To find compatible amplifiers, speakers, or anything else in between, look for the AirPlay logo.
Amplifier - integrated
The design of any audio amplifier is made up of two main sections, the pre-amplifier and the power amplifier. The 'pre' takes care of choosing your source, setting the volume and any other adjustments such as bass and treble controls. The 'power' is the bit that powers the speakers! High-end set-ups commonly use separate pre and power amp units, but most of the time both bits are in one box. This is known as an integrated amplifier.
Amplifier - power
A power amplifier is perhaps the simplest piece of hi-fi equipment. It's the one that makes audio loud! They most commonly have two inputs and two outputs; one for the left channel and one for the right. The sound comes in from the preamp via an interconnect cable (either phono or XLR) and goes out via speaker cable. The advantage of breaking this part of an amplifier design out into a separate box is that the high current amplification circuitry can generate interference that has a negative effect on other signals in an integrated design.
Amplifier - pre
The pre-amplifier is the bit that you interact with, choosing the source and setting the volume, as well as any bass and treble adjustments. Unlike a regular integrated amplifier, it can't connect directly to speakers; you'll need a power amp to boost the signal to the right level first. You also get pre-amplifiers designed for home cinema use, though these are normally referred to as processors. Some high-end equipment, such as music network streamers, have pre-amplifiers built-in, for use with power amplifiers or active speakers (See amplifier - power & passive / active (speakers).
The original meaning of the word 'analogue' is replication. In hi-fi terms we often use the word to describe the opposite of 'digital'. An analogue version takes the original material, be it sound or picture, and replicates it in a quantifiable, viable format. One example of this is vinyl, where the sound waves of the music are represented in the physical variations of the records' grooves. Another example is in traditional film, where each frame is captured as a physical photograph on a film reel. The projector flashes on each photo, projecting a “motion picture” on the screen. Other examples can include radio waves or a physical video or audio cassette.
AptX is an Audio codec for storing and sending compressed information wirelessly between devices. It's most commonly used for Bluetooth-ing music to a compatible speaker or dock. It provides the best bandwidth for sending media to a compatible receiver, meaning when you stream music from your phone, tablet, laptop or any other compatible device, you can enjoy the best possible sound quality and all wire-free!
The displayed width of an image divided by its height. Chances are, at some point, you've noticed black bars either along the sides or the top and bottom of your TV screen. This is because whatever you're watching has been made in a different aspect ratio to the screen. Nearly all TV shows since the mid 2000s have been made in the 16:9 'widescreen' format that's the same shape as your TV. Since the advent of colour film, a lot of movies were made in this shape too. However, older TV shows and movies are in the square-ish '4:3' aspect ratio. Most movies use a much wider image for a more epic appearance, which you may hear referred to as 21:9 or 2.23:1 (the screen is 2.35 times wider than it is taller). To fit these different ratios onto your 16:9 TV or projector you can stretch them, (which can distort the image), zoom in, (which cuts off the edges), or display black bars on the top or bottom - or sides when watching 4:3 content. The majority of TVs let you choose which you prefer from these options.
AV Receiver (Also known as a Home Cinema Amplifier)
Think of this as the heart of your surround-sound system. The term "receiver" refers to the fact that it has a built-in radio tuner - but it's much more than that! Capable of receiving signals from a variety of sources such as Blu-ray players or over-the-air TV boxes, the receiver decodes the surround sound information and amplifies the speakers. They can also pass the video signal on to the television. This means they can act as a complete switching hub for your audio and visual entertainment. Some support various audio formats such as Dolby Atmos and DTS:X. You can also connect audio sources, such as iPhones/mp3 players, and many now offer wireless music streaming to cover all your home entertainment needs.
It's the rhythm in your reggae. It's the boom in your Bond film. This is the lowest part of the frequency range, which is reproduced by woofers and subwoofers in loudspeakers. The rumbling often heard in home cinema is a classic example of extreme bass.
Bit rate / bit depth
Bit rate is effectively a measure of quality of a digitised audio or visual signal. Measured in Kbps or Mbps (Kilo-bits per second or Mega-bits per second; a Mega-bit is 1024 Kilo-bits), it's telling you how much data is used every second. A higher number means better fidelity, as the digital description of the sound or picture is more detailed. This does come at the expense of a larger file size however. When people talk about 'bit depth' (e.g. 24bit audio or 10bit colour) this refers to the range of data that can be described by the file. 24bit audio, for example, is able to produce more subtle changes in volume than the 16bit standard found on CDs, and higher bit colour can show a greater range of shades between primary colours.
Blu-ray disc (BD)
They look like DVDs, but they're a whole lot better. Not only do they offer amazing quality high definition picture, but you'll also enjoy better sound quality than DVDs or HD movies streamed from the web. Another advantage over downloads is access to special features, which can include information appearing over the top of the movie image: pretty cool for film buffs! New releases tend to cost only a pound or two more than DVDs and all Blu-ray players will play your existing DVD collection too. A no-brainer for film and TV fans.
Named after the ancient Nordic king Harald "Bluetooth" Gormsson… (Would we lie to you?), this wireless media standard facilitates the transfer of data between compatible devices. Most commonly it is used in smartphones or tablets to stream music through a speaker system of some kind. The capability is built into a huge range of audio devices from hi-fi systems and soundbars to headphones. There are also a range of discreet units available to add-on to existing systems.
When referring to a TV or projector, this is the amount of light that is emitted from any screen or projector and perceived by the eye. Brightness of screens is measured in cd/m squared (candela per square meter), while for projectors it is measured in ANSI (American National Standards Institute) lumens. In both instances the brighter the image, the higher the rating. Remember, as with power in an amplifier, the biggest number doesn't always equate to the best performance. Equally, if a TV or projector cannot deliver a bright image, you'll need to be able to control the light in your room, and this isn't always possible.
This handy bit of technological hocus-pocus lets you send content between compatible devices, without the need for cables. Miracast can support 1080p video with 5.1 surround sound, meaning its most common use is to stream content from a phone or tablet to a television. It also works from Wi-Fi direct, meaning the signal travels directly between devices rather than having to go through a wireless router. Google Cast is another popular option for picture, while music streaming services such as Spotify use a version of 'casting' to playback on compatible hi-fis/speakers.
When saved as raw data, audio files take up a lot of space and video an astronomical amount. The cameras used to film The Hobbit, for example, use up to 5GB a minute! Therefore the files need to be squeezed down, or compressed, somehow. A codec is basically a key to compressing a file so that it's a lot easier to manage. However, each codec is like a different language, and whatever's playing it back needs to speak the language too. This isn't as much of a problem as it used to be; Smart TVs, Blu-ray players and other components tend to be compatible with lots of different codecs. That said, if you are interested in playing back videos from a USB drive or similar, it's worth checking compatibility. The same applies to music files. Remember – the codec is the language the compression uses, as opposed to the file type, which is the vessel for all of the information.
The greater the amount of colours a screen can produce, the more natural the image will be. LED backlit and traditional LCD screen shine a blue light through a yellow phosphor film to create white light. This light is then shone through red, green and blue filters (sub pixels) to create the full colour range. Quantum dot LED TVs create brighter colours and therefore a larger, more dynamic range. OLED technology can produce the widest range of colours (See quantum dot and OLED for more information).
The highest quality analogue video connection available. It's been completely overtaken by HDMI, with many units now offering no alternative to this ubiquitous new connection. However, if you have a particularly good older DVD player, or a games console like the Nintendo Wii or Sony PlayStation 2, it's still worth hunting down a component cable and using this input on your TV.
This is the difference between the lightest and darkest content that a screen or projector is capable of producing. A high contrast ratio is a desired spec for any display; being able to display a deep black alongside a bright white is what makes images appear punchy. However, due to various methods of measurements, remarkably different measured values can sometimes produce similar results. Some manufacturers no longer list contrast ratios, as claimed figures were becoming almost comically high. In typical viewing situations the contrast ratio is significantly lower than these claims, making it harder to distinguish between different devices with very high contrast ratios. OLED TVs produce infinite contrast due to their absolute pure blacks. The best solution is to visit our stores and compare with your own eyes.
The part of a loudspeaker that splits the incoming audio signal into separate frequency ranges, and then sends these signals to specific drivers, such as, in a two-way design, the tweeter or woofer. They have a huge influence over the final sound of a loudspeaker design. The better the crossover, the less the sound will distort at certain frequencies.
Digital Audio Broadcasting. Digital radio transmission gives a greater selection of radio stations, and wonderful ease of access. What's more it allows the broadcast of information like the title of the current track or programme. Some products are compatible with DAB+ which offers higher quality audio. This system isn't yet used in the UK, but you'd be covered if we did ever change. One advantage of DAB radio is its ease of use tuning in - no more white noise between stations. An alternative is Internet radio, which offers many of the same benefits as DAB.
Standalone DACs (digital-to-analogue converters) squeeze the maximum sound quality from digital music (including CDs, streamed tracks and more). Digital files played through a decent DAC will achieve significantly superior levels of detail compared to the cheap DAC chips built into most digital kit. In essence, a DAC takes the digital stream of 1's and 0's and converts them into an analogue waveform. This waveform is analogous of the original sound, so the better the DAC, the more accurate the sound produced. A good DAC should be heard in comparison to poorer DACs for the most obvious demonstration of quality. Why not pop in for a demo and hear the difference for yourself?
This can refer to storage (data) or signals. The word 'digital' comes from the Latin 'digitus' (meaning 'fingers', as in 'digits for counting'). Digital data is a discrete (individual) discontinuous (has a precise beginning and end container) representation of information. For example, this can be an mp3 file on your phone, or movie files on a Blu-ray disc. A digital signal, on the other hand, is the transfer of information. This can be bitstream (a continuous signal of binary 1's and 0's), or a more complex waveform (see bit rate and bit depth for more information).
How big is yours? Where possible, we try to include dimensions of a component both including and excluding any stand, bracket or feet it may come with. For accuracy, we always use millimetres in our measurements. Make sure to check you can fit your chosen items in the space you have in mind for them!
DivX is a brand name for products created by DivX Inc., which have become popular due to their ability to compress lengthy videos into small sizes, while maintaining decent video quality. It is commonly associated with burning or ripping video content onto a hard disk. As HD has become more popular, DivX has become less common, but it's still compatible with a wide range of devices.
See entry for "UPnP".
Over the years few companies have been quite as important for cinema as Dolby. From the origins of surround sound, through to completely immersive cinema, Dolby have brought many cutting-edge formats to the home.
The next dimension in surround sound - Dolby Atmos creates an immersive experience like never before. Extra speakers fire sound from above or 'bounce' sound from the ceiling, using an innovative design. Many modern AV receivers can easily be upgraded with the addition of Atmos speakers. Far more realistic surround effects are created using advanced 'object based' sound mixing techniques. Click HERE for more information in our useful in-depth guide to Dolby Atmos.
This is the technology that puts the ‘cinema’ in ‘home cinema’. Pick up almost any DVD or Blu-ray title and you will find this almost-ubiqutous surround sound format as an option. Typically 5.1, sound is mastered in a multi-channel format to give an immersive surround sound experience. You can also find Dolby Digital on many movie streaming services too.
Dolby Digital EX
Dolby Digital EX takes the Dolby Digital 5.1-channel setup one step further with an additional surround channel (reproduced through one or two speakers) for extra dimensional detail and an enveloping surround sound effect. It was used on very few DVDs and has now been superseded on Blu-ray by the 7.1 capabilities of Dolby TrueHD.
Dolby Pro Logic
Dolby Pro Logic was the foundation for multi-channel home cinema. Originally, it was a way of fitting the signal for a rear speaker into standard stereo sound. While that function still works perfectly, its most common use today is making use of all the speakers in your set-up even when what you're watching is not in surround.
Dolby Pro Logic II, Dolby Pro Logic IIx and Dolby Pro Logic IIz
Version two of Pro Logic has had a number of incarnations over the years, with the first being Pro Logic II. It turns a properly encoded two-channel source into a full-blown 5-channel signal. Other improvements include better channel separation and a full bandwidth, stereo signal to the rear speakers. The IIx version offers 6.1 or 7.1 channel playback. This is taken further still with IIz. It expands a 5.1 signal to 7.1 or even 9.1 with front height speakers.
Dolby TrueHD is a lossless audio format (see lossless) commonly found on Blu-ray discs. This gives equivalent quality to what the engineers would have heard when mixing the soundtrack in the studio, at a sample rate of up to 192 kHz, as opposed to the 48 kHz maximum of regular Dolby Digital (see sample rate). This format isn't possible on a DVD as there simply isn't enough room on the disc. For those who've invested in an extra pair of rear speakers, it also supports discrete 7.1. There was a time when only a handful of Blu-ray players and AV receivers were compatible, but it's now reached near ubiquity. That said, it's still worth double-checking if you're interested in getting this massive upgrade.
A driver is a specific word that describes the individual cones within a speaker. For example, a two-way speaker features two drivers, one for the high frequencies (known as a tweeter) and one for the mid-range and low frequencies (known as a woofer or mid/bass driver). There are different types of driver, but ultimately they all vibrate to create sound waves.
DTS, Inc. started its work on a surround sound format nearly four years after Dolby Laboratories, yet managed to bag some quite notable backers. Not least of these was Steven Spielberg, who needed a breakthrough format for his 1993 production Jurassic Park. It was also the first home release to feature DTS. Since then DTS has released many formats, both 'cinema' and 'home', to improve the movie experience.
This uses either a traditional 5.1 soundtrack and converts it to 6.1 (with an additional surround speaker), or DTS-ES Discrete 6.1, which has all 7 audio tracks mastered and recorded to the soundtrack, for a more realistic surround sound. The latter of which was seen as an improvement over Dolby's Digital EX, which did not feature a discrete 7th channel.
DTS-HD High Resolution / DTS-HD Master Audio
DTS' two high definition audio formats. 'High Resolution' was the first of the two, offering 96kHz sampling rate (see sample rate) and 24 bit depth resolution (see bit rate / bit depth). 'Master Audio' has subsequently replaced 'High Resolution' as it contains up to 192kHz/24bit audio.
DTS Neo:6 / DTS Neo:X
These processing standards take a 5.1 mix and convert it to either 7.1 (Neo:6) or up to 11.1 (Neo:X). The 11.1 set-up utilises a centre speaker, a left-right stereo pair, two front-wide, two front-height, two rear-side, two rear speakers and a single subwoofer.
The original surround sound format, DTS Surround offers a fully discrete 5.1 set-up. This uses a centre, a left and right stereo pair and two rear speakers. It also includes a subwoofer track for the LFE (low frequency effects).
An 'object-based' audio codec (see Dolby Atmos). The advantage of this format is the processor (or home cinema amplifier) can complete 'on-the-fly' calculations based on the speaker configuration of the room, giving you demonstration room quality home audio, regardless of your room size or layout.
DVD-Audio is a high quality format, which uses a DVD's superior storage capacity to offer sonic improvements over conventional CDs. Not only can it deliver stereo at 24-bit/192kHz quality, but also surround sound recordings in 24-bit/96kHz. Sadly, it never really caught on and there is extremely limited software availability, with some releases fetching collector's prices. These days, Pure Audio on Blu-ray tends to be the high-resolution audio physical disc of choice.
DVI (digital visual interface) is a video connection with a large rectangular connector that was commonly used by HDTVs and Projectors, but was quickly phased out as HDMI gained popularity. Unlike HDMI, DVI only carries picture information, no sound or other data. If you're buying all new equipment you needn't worry, but DVI to HDMI cables are readily available should you find yourself in need of one.
The dynamics of a system refers to its reproduction of the quietest and loudest parts of a piece of music. The difference between these is referred to as 'dynamic range'. A highly dynamic system is desirable as it will be able to go from extremely quiet to extremely loud as swiftly and easily as an F1 driver going round a racing track, and also express far more subtle changes in volume. You may come across people complaining about a recording having poor dynamic range, saying that it is "overly compressed". This basically means that, even if you have a very dynamic system, the recording makes it sound otherwise. It's perhaps best not to bring up this issue with any audiophile friends unless you're prepared for a lengthy rant!
EPG (Electronic Programme Guides)
With Digital TV now ubiquitous, everyone has access to an EPG, though you may not know that's what it's called! It's the technical term for the TV guide you can bring up on-screen to look through what's on across all channels. Some internet connected services such as YouView and Freeview Play enable you to access programs from catch-up services, all from the one EPG.