Dolby Digital Audio - LG LHT754 Troubleshooting Manual

Dolby Digital Audio

Dolby Digital soundtracks are very popular with many commercial DVD-Video releases. However, the
DVD specification does not require that the soundtrack have to be Dolby Digital. There are other formats
such as MPEG audio, PCM audio, and DTS. Dolby Digital, DTS, and MPEG audio record audio samples
in compressed format while PCM audio samples are uncompressed.
The full name of Dolby Digital or AC-3 is Dolby Digital 5.1. The name describes the sound distribution
on six channels in space. All the six channels are compressed into one stereo file, which is unpacked
with a special decoder and divided into six audio columns. According to the AC-3 format the sound is
heard from five wide-band columns: left, right, rear left, rear right, central and from one narrow band,
which is used for low frequency effects (LFE) only. This LFE effect is better felt than heard in the movie
theatres. The number 5.1 indicates five general channels and one LFE channel. Dolby Digital is a great
step forward comparing to Dolby Surround, concerning perception of the spatial sound. The following
illustration shows an ideal setting to enjoy
Dolby Digital soundtracks.
The Dolby Digital format supports soundtracks
in a variety of formats such as mono, dual
mono, stereo, Dolby Surround stereo, Dolby
Surround 5.1 (also commonly known as AC-3).
DVDs with DTS audio soundtracks are required
to include a Dolby Digital audio track. Each DVD
disc can have up to 8 different soundtracks.
Commercial NTSC DVD-Video usually contains
the first soundtrack in Dolby Surround 5.1
and the secondary soundtrack in Dolby Digital Stereo.
Home Theatre Troubleshooting - 2007