It is simply the association of the video and the chain of reproduction of the sound. The video part can be insured by a television set and the sound part by a chain hifi.
The popular purpose is the obtaining of an atmosphere comparable to that of the halls of cinema: the cinema at home, thus...

The home-cinema gives the impression to be in the heart of the action! When a helicopter crosses the screen, we lower the head and the dog runs after the tumbler thrown untidily on the ground by the star of the film! Seriously, I noticed it several times...

The video part has to present a compatible large-sized screen with the size of the room. The format 16/9 is particularly adapted well but the format 4/3 can also agree.
The sound part is the most important because it is it which is going to give the atmosphere and the impression of space. There are several techniques, more or less effective to return this impression. They are quite based on the presence of several loudspeakers distributed in the room...

It can be insured by:

• A television set of size adapted to the room.
• An overhead projector (bigger than a TV).
• A video-projector, regrettably very expensively!
• A plasma screen or LCD, still very expensively!

The HDTV (high definition TV)

Here are the various used techniques:

The sound is distributed on two channels, left and the right.
It is a small improvement. The space is only distributed in front without giving the deep impression.
It is the case of the stereo TV NICAM Connected or not with a chain hifi traditional.

THE SOUND (Suite)...

Invented by Jim Fosgate then given up in Dolby Laboratories, It is the first one proceeded who allows to give a real depth to the sound scene. The sound is distributed in 4 ways: before left, central, before right and 2 "surrounds" defer, 1 to the left and the other one to the right. Surrounds being identical. Sources: TV NICAM, satellites, VHS, DVD.

This process returns well the atmosphere of a film. We are already IN the action. We hear surrounding noises, the rain which falls around us. The film seems more realistic. We are IN the movie!

Invented by Dolby Laboratoires, This process distributed the sound in 6 ways (5+1 ): Before left, central, before right, left back, right back "more" 1 sees for the infra-grave. Ways rear "surrounds" are different and restore all whole sound spectre. Source: DVD.

The listening of Dolby Digital is really impressive. The explosions shake us literally and planes make us lower the head, while trying to evade the balls which whistle to our ears...

This process is due to Digital Theater Systems Inc and distributed the sound in 6 ways (5+1 ) as the Dolby Digital but the sound is less compressed and the treatment digital is different. Source: DVD.

The listening is really spectacular! Difficult to tell you which system to choose between DD and DTS...

Always invented by Jim Fosgate then given up in Dolby Laboratories , This new process works on the same principles as the DD and the DTS but with a different signal processing. This new process needs 2 ways only. The advantage of the Dolby Surround Prologic II is that it works, as the DPL-I, with satellite bouquets and cassettes VHS as with DVD...