Dolby Surround / ProLogic question

[Jukka]

I've seen a few posts on here about Dolby Surround / PL and that mainly it is a DEcoding not an encoding.

I'm not that bothered by that argument, however my question is that if PL (which is what I have on my TV, PL NOT PL2) is a 'phantom' decoding why do some sources not provide any surround info?

My CDs played through my DVD player do, but some of my VCDs dont. Any thoughts?

Specifically I have a DivX movie that doesn't provide any surround sounds, it is MP3 @ 128k, whereas others at this bitrate do.

Many thanks in advance,

Jukka

[crazeplaya]

Are you sure that the original movie had Pro Logic?

[Greenspock]

... if PL (which is what I have on my TV, PL NOT PL2) is a 'phantom' decoding why do some sources not provide any surround info?

PL or Pro Logic (I/II) is a decoder or type of decoder. A set of 'rules' or 'equations' that tries to take something like a two channel audio source and make it/decode it/convert it (whatever) into a multi-channel (>4) output. Hope this helps some.

[sterno]

Real Dolby Surround actually does involve special encoding, information for the center and back channels is encoded in to the two stereo channels. Prologic is the name of Dolby's decoder for Dolby Surround playback. A Prologic decoder can sometimes give you some limited surround effects with non-Surround material, but in my experience it usually only gives you a little bit of center-channel audio.

[Jukka]

Ok,

so is there a way that we can 'fool' the dolby decoder to give (limited) surround from a 2 channel source? I seem to remember reading something on this site about it and it involved using joint stereo instead of stereo at certain bitrates but now I can't find it!! Or is there some other piece of software that can produce a surround mix from 2 channel?

Jukka

[JimJohnD]

Read this post from....

https://www.videohelp.com/forum/viewtopic.php?t=124299&highlight=

It should point you in the right direction.