[vlc-devel] Re: [vlc] re : Re: Surround sound?

[Paul Forgey]

Maybe a dematrixer would be a fun audio filter to use.  AFAIK, Dolby's 
EX encoding isn't done discretely, but de-matrixes the back channel 
from SL and SR.  Similar with DTS, should it be implemented (I saw a 
parser for it in there, but no decoder).  While DTS-ES uses discrete 
channels unlike DD-EX, SL and SR are still matrixed for the benefit of 
situations just like this one.

At least this was as things were a few years ago, and I haven't really 
kept on top of things too much since then, so I could be wrong by now.

This same filter could then be used, with the proper options to tell it 
to behave differently, to do other fun things like Pro Logic decoding.  
For example, in this mode, it would take two channels rather than 6 and 
output 4 using a 90 degree phase shift.  (SL and SR are dematrixed 
using a 45 degree phase shift).  Of course, to do proper Pro Logic 
decoding and call it that (ignoring the code definitely would NOT be 
licensed from Dolby! :) the process also needs some bandpass filters.

I can see from looking at the code and documentation the audio stream 
is extremely well thought out, including management of all the channels 
beyond stereo.

On Wednesday, June 4, 2003, at 08:05 AM, <gbazin at altern.org> wrote:

>> I'm on a PC. So getting a Creative Audigy 2 would give me
>> 6.1?
>
> VLC doesn't support 6.1 but it does support 5.1 audio.
> Once liba52 supports Dolby Digital (Surround) EX it should be quite 
> easy to modify VLC to support 6.1 for those DVDs that use this 
> encoding (Most DVDs use 5.1 only).
>
> If you try to play a 5.1 source with VLC on a 6.1 hardware, the rear 
> center channel will just not be used.
>
> --
> Gildas
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