[MPlayer-dev-eng] [PATCH] Automatic downmix

[Tobias Diedrich]

Clément Bœsch wrote:
> > I'm not proposing to have this as default, but optional because it
> > makes sense to have this option for people with an old dolby
> > surround amplifier.
> > 
> 
> Well then it may belong to another patch; downmix codecs builtin don't
> seem to behave like that.

Ok, let's leave it out for now.

> > For best usability I'd imagine having a 'downmix' filter where you
> > can just specify the unnormalized 5.1 downmix matrix would be great
> > I think.
> > i.e. "-af downmix=1.0:1.0:0.707:0.707:1.0:1.0" (downmix=L:R:C:LFE:Ls:Rs)
> > and the filter would normalize to a sum of 1.0 internally.
> > 
> 
> Won't be so hard to do, but once again, another patch I think (it's
> already hard to get one accepted so… maybe later :))

Maybe I'll look at it later.  I was thinking of writing a filter
like this when I saw there was already a thread on downmixing and
joined the discussion. :)

> > Oh, and this links explains where the .707 for C and LFE is coming from:
> > http://ac3filter.net/guides/mixing_matrix
> 
> Ok I think I get it. So do those values seem fine to you? :
> 
> 3 input channels
> 1.0000:0.0000  0.0000:1.0000  0.7070:0.7070
> 0.5858:0.0000  0.0000:0.5858  0.4142:0.4142
> 
> 4 input channels
> 1.0000:0.0000  0.0000:1.0000  1.0000:0.0000  0.0000:1.0000
> 0.5000:0.0000  0.0000:0.5000  0.5000:0.0000  0.0000:0.5000
> 
> 5 input channels
> 1.0000:0.0000  0.0000:1.0000  1.0000:0.0000  0.0000:1.0000  0.7070:0.7070
> 0.3694:0.0000  0.0000:0.3694  0.3694:0.0000  0.0000:0.3694  0.2612:0.2612
> 
> 6 input channels
> 1.0000:0.0000  0.0000:1.0000  1.0000:0.0000  0.0000:1.0000  0.7070:0.7070  0.7070:0.7070
> 0.2929:0.0000  0.0000:0.2929  0.2929:0.0000  0.0000:0.2929  0.2071:0.2071  0.2071:0.2071
> 
> 7 input channels
> 1.0000:0.0000  0.0000:1.0000  1.0000:0.0000  0.0000:1.0000  0.7070:0.7070  1.0000:0.0000  0.0000:1.0000
> 0.2698:0.0000  0.0000:0.2698  0.2698:0.0000  0.0000:0.2698  0.1907:0.1907  0.2698:0.0000  0.0000:0.2698
> 
> 8 input channels
> 1.0000:0.0000  0.0000:1.0000  1.0000:0.0000  0.0000:1.0000  0.7070:0.7070  0.7070:0.7070  1.0000:0.0000  0.0000:1.0000
> 0.2266:0.0000  0.0000:0.2266  0.2266:0.0000  0.0000:0.2266  0.1602:0.1602  0.1602:0.1602  0.2266:0.0000  0.0000:0.2266

Yes, those look ok, thanks.

-- 
Tobias						PGP: http://8ef7ddba.uguu.de