Surround Sound

Surround Sound is a general term for additional sound signals that are added to a simple stereo track to enhance audio playback. Most DVDs include a 5- or 6-channel (also called 5.1 channel) sound track. They also have a matrix-encoded sound track which contains the surround sound channels within just two audio channels (matrix-encoded stereo). These can be sent to a stereo receiver or a computer sound card.

Likewise, streaming audio on the Internet can also be matrix-encoded and sent to your computer. With an appropriate sound decoder and speakers, you can play back these surround sound presentations. Without a surround sound decoder, the additional sound signals are skipped and a standard stereo track is played.

RealPlayer can reproduce matrix-encoded surround sound stereo from either local sources (CD/DVD) or from streaming audio. If the clip you are playing does not contain matrix-encoded surround sound, then the Player will reproduce only standard stereo or mono audio.

How do I play back surround encoded content?

To playback the sound correctly, connect your sound card's stereo output to a surround-enabled receiver and switch the receiver to surround decoding. That's all there is to it.

To obtain the best surround sound, a surround-enabled receiver requires an unmodified signal so it can properly decode the surround sound. Therefore, disable the Equalizer in RealPlayer to maintain an unmodified signal. In addition, open your sound card's Properties dialog from the Windows System Properties) and ensure that no "wide stereo" (such as "qsound") or similar options are selected (advanced properties).

Dolby ProLogic and Matrix-encoded Sound

Maxtrix-encoded Dolby sound is four channels of audio (left, right, front center, and rear center) encoded within two audio channels. When played with a simple stereo system, it is played as standard left and right channel stereo. When the two-channel matrix-encoded signal is sent to a sound system with a Dolby Prologic decoder, the four channels are extracted and can be played as a surround sound presentation.

Most TV shows today use Dolby ProLogic (look for the "Dolby Surround" logo at the end of the credits) to encode multiple audio channels. The transmitted audio signal, or feed, is just two channels, but an audio system with a Dolby decoder will separate these into four channels of surround sound.