First used in cinemas, the Dolby Digital
signal information is placed on the film between the sprocket
holes of the film and now is the standard format for DVDs.
Dolby Digital has been developed using the latest digital
technology. Following the basic theory of the Dolby system, Dolby
Digital records, transfers and plays back each channelís signals
with all digital signals. In addition, each channel is recorded
independently. Therefore, unlike the conventional analogue Pro
no signal is pushed into the two channels by matrix treatment. As
a result, each channel's divisional characteristics have been
enhanced and stable playback has been achieved. Consumer-format
Dolby Digital is basically the same as that for theatre use; only
the data rate is different.
Dolby AC-3 meanings are 3rd developed for AUDIO CODING form. It
was designed as a versatile low bit ratecoder for' Multchannel
Digital Audio System'. The name AC-3 is the predecessor to Dolby
Digital, today it generally refers to sound system used on some
laserdisc players produced prior to the advent of DVD. The use of
AC-3 requires a LD with AC-3 RF out and of course the use of an
AC-3 amplifier. The AC-3 RF output is a purely digital RF audio
output, the signal has to be decoded by a RF to digital decoder
before it can be connected to the digital input of a Dolby Digital
Amplifier. Some high end amplifiers have a RF decoder input built in to
the amplifier if you don't have a laserdisc player you wont need
The latest version of Dolby Digital is Dolby Digital EX which adds
2 extra rear speakers to your theatre setup this type of system is
called a 7.1 system.
John Logie Baird is often
considered the inventor of
Television his original design is
far different from the sets that first became popular. his
design was mechanical in part and only could display 30 lines.