surround sound

[tk421]

I noticed something while playing cds through my receiver. If I leave Pro-Logic turned on, some signals are sent to the rear speakers. Everything still comes through the front speakers. I can't seem to tell what is different about the sounds in the rear, but it does seem consistant.

Does anyone know anything about this? I thought if I knew more about it that it may be possible to create songs with this in mind, and create a fake surround sound effect.

[Doogle]

I think the way pro-logic decoders like that work, is:
left and right the same goes to the centre channel
left and right with a phase offset of 180 degress (eg. flip the right channel) goes to the surround channel(s)
otherwise it's stereo as normal and uses the left and right channels.

Of course it's not gonna be as good as having x actual channels, but it still quite fun to play with.

Someone else may be able to be a bit more exact about it... this is from playing around with soundblaster code and my parents (vaguely pro-logic) hi-fi about 8 years ago.

[tk421]

Thanks, I was kind of starting to come to that conclusion.

[soldier43]

There is a DirectX plugin by Sonitus that allows you add surround sound effects to a clip of music...

[popsych]

Also Samplitude has 2-channel surround aka pro logic features built in and you can position sounds as if using proper surround

[ew]

Wave Arts has a new plugin called Panorama that synthesizes quasi- surround (including height ) effects with normal stereo outputs- it's pretty cool.
http://www.wavearts.com/Panorama.html
ew