[pulseaudio-discuss] Mono Upmixing Only

Alexander E. Patrakov patrakov at gmail.com
Wed Apr 3 20:41:27 PDT 2013

2013/4/3 Tanu Kaskinen <tanuk at iki.fi>:
> On Wed, 2013-04-03 at 10:20 +0100, Carl Gridley wrote:
>> Wow, wasn't expecting code so quickly - thanks!
>> I've been away for a bit. Is this working and done? Do I need to get
>> PA 3 and a patch on my system or is it all good and in the queue for
>> an offical release in the future?
> You need to apply the patch yourself, because my solution was not
> considered good. It seems that this was only discussed in IRC, not on
> the mailing list. A bug report has been filed, which contains the
> explanation why the solution was not accepted:
> https://bugs.freedesktop.org/show_bug.cgi?id=62588

I'd say that the "no should mean no" argument is at least incomplete,
in the sense "more discussion is needed". First, did the opponents
present a use case when a pure "no" (with all associated side effects)
would yield the correct result for all use cases?

Second (semi-trolling, don't take too seriously) remixing by channel
copying and linear summation is so old-school! No modern 5.1 receiver
does it by default when fed a stereo signal over SPDIF or HDMI. They
have a US-patented upmixing algorithm from Dolby inside, using Z
transformers and even non-linear elements, and most so-called "stereo"
records are produced with that "matrix decoder" in mind. So, once this
fancy upmixer is completely reverse-engineered, it should be an option
at least in the countries where the patent is invalid. And yes, this
does mean that the "enable-remixing" option is a misnomer, as it is
not a boolean.

Alexander E. Patrakov

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