Subject: Re: [linux-audio-dev] surround encoding
From: Steve Harris (S.W.Harris_AT_ecs.soton.ac.uk)
Date: Tue Oct 16 2001 - 19:32:43 EEST
On Tue, Oct 16, 2001 at 04:46:33PM +0300, Juhana Sadeharju wrote:
> >From: Steve Harris <S.W.Harris_AT_ecs.soton.ac.uk>
> >
> >DTS OTOH is patented, but I've a feeling the the line format is just the
> >2 stereo channels plus Sr, Sl and LFE, uncompressed on the data channels,
> >so its hard to imagine that thats covered by the patents.
> What is left is that people could make surround sound for their
> own fun or use it in student works, for example. But if a step
> to commercial business (DVD, exhibitions etc.) is made, they
> have to pay lisence. Of course, DTS company would set the final
> rules. Would this be worth of asking?
I don't see why not. Dolby have been asked in the past, but DTS is
produced by another company. I don't know what thier opinion is. I'm not
quite clear on IP laws, but I think that in the US if they aren't willing
to give you the format there is no legal way of implementing it.
> Is the MPEG 5.1 surround patent free? We could use it if no other
> system is available in commercial amplifiers besides those three.
I expect it is based on MPEG1-L3 so its a bit open to interpretation, but
as with AC3 you're going to need a serious processor to encode that in
realtime. Also, I think MPEG 5.1 amps are only easily available in Europe,
and becoming less common.
> In extreme, people would have to design a new free surround format
> and offer the decoder to amplifier manufacturers.
What about ambisonics? I think the decoder hardware is expensive but
aren't there some LADSPA plugins that can encode it? It's technologically
superior to the 5.1 and 6.1 formats anyway IMHO. Though I asuming that the
point is to produce something that can be played back on generic domestic
equipment.
- Steve
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