[vdr] Re: 5.1 Sound with analog soundcard?

[Jarkko Santala <jake@iki.fi>]

On Wed, 2 Jul 2003, Guido Fiala wrote:

> On Wednesday, 2. July 2003 17:27, Marcel Wiesweg wrote:
> > Am Mittwoch, 2. Juli 2003 12:05 schrieb Markus Schorer:
> > > hi,
> > >
> > > sure it's possible.
> > > use a52dec and let it decode to 5.1 (or some other fixed setups).
> > > i'm doing the same. it works really good.
>
> Can you give an commandline example where i can feed a52dec with _any_
> stereo-pcm/mp3-data and it makes 5.1 sound? So far i understand this program
> can only play ac3-frames just like ac3dec, if your mpeg-stream does'nt have
> it you hear nothing - unfortunately except Pro7 actually nobody has the money
> to send such streams - or maybe they are reluctant to buy a licence
> themselfes ?-)
>
>
> Maybe it's just as Onno mentioned - "legal reasons" :-(
>
> I simply think, that a software-solution to this is more flexible and can be
> adapted so that it works _reasonable_ with any data, depending on if it is
> just stereo or dolby you can switch to make it sound right, in case of a
> piece of hardware (not even cheap) you are bound to what it thinks it
> detected is correct... did'nt i buy for an 5.1 sound-card? should'nt there be
> already the license be paid to do dolby-decoding with it?

Well. To get dolby surround from 2 channels, you'd need a dolby surround
decoder which is probably the "legal reasons" refer to; you can't legally
make one with a license from dolby laboratories.

Just to clear one thing up: there is _no_way_ to get 5.1 sound from
stereo, what you can get is dolby surround which is 4 channels (left,
center, right and _one_ surround). And the surround channel is a far cry
from real distinct surround channels in 5.1 which you can only get with
dolby digital, dts or multichannel mpeg audio.

If you add some low/high pass filters, you could get some sort of 4.1
surround. Additionally some pre-dolby digital a/v receivers had some sort
of "thx" processing from lucasfilm which would separate the rear channels
into two, but again, nowhere near real 5.1.

To sum things up, buy a proper a/v receiver, they don't cost anything
these days and as a bonus you will get a digital connection between your
pc and your amp, removing all the problems with analog sound transfer
between the two devices. Basically, you can't have a proper home theater
setup without buying one. :)

And no, real speakers don't have plastic enclosures. And yes, this is
completely OT.

	-jake

-- 
Jarkko Santala <jake@iki.fi>            http://www.iki.fi/~jake/
System Administrator                    2001:670:83:f08::/64


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