Re: [LAD] Mixing audio: Implementing pan and balance

On 03/14/2013 12:37 PM, Paul Davis wrote:
>
>
> On Thu, Mar 14, 2013 at 6:42 AM, Jörn Nettingsmeier
> <nettings@email-addr-hidden <mailto:nettings@email-addr-hidden>> wrote:
>
> On 03/12/2013 08:08 PM, Tim E. Real wrote:
>
> But having said that, yes I'm wondering about a true 'stereo
> pan' feature.
> How would such a feature work?
>
>
> there is no one true stereo pan.
>
> a pan law for intensity stereo (i.e. a panned image or an XY
> coincident microphone pair) would increase one channel and decrease
> another such that the total energy remains constant. a cosine/sine
> law is usually used, because
>
> cos^2 + sin^2 = 1
>
> ardour3 attempts to do this, by allowing you to reduce the width (by
> introducing crosstalk), and then letting you move the compressed
> image left or right. sort of works, but only for pan-potted stuff.
>
> a pan law for run-time stereo (i.e. spaced omnis) would have to use
> delays, leaving the original level intact.
>
> the ardour3 panner gets this type of signal horribly wrong, because
> you _never_ want to introduce crosstalk in spaced omnis - instant
> comb-filtering hell.
>
> for stereo techniques that incorporate both run-time and intensity,
> such as ORTF, NOS, EBS, you-name-it, you need different amounts of
> gain change _and_ delay.
>
> that's why nobody wants to use a ready-made stereo balance control -
> it is almost guaranteed to do the wrong thing for the source
> material at hand.
>
>
> git add libs/panners/spaced_omni_panner
> git commit
> git push

point taken :)

the problem is, you usually have a mixture of the above. hence, no way
to get the stereo panner right. unless the user knows exactly what s/he
is doing, and then s/he doesn't really need a stereo panner :-D

btw, sorry for the pot shot at ardour specifically - in fact, most if
not all DAWs get it wrong. iirc, some DAWs with a focus on classical
(sequoia, pyramix) have some code to mogrify complex stereo, but i
haven't used it.

my approach to complex stereo re-panning is: split the signal into two
mono busses, add a delay, add eqs if you have to, move faders.
and while we're at it, the same approach works for processing in the MS
domain. it's painful enough to only use it when you really need it, and
hard enough to discourage casual users :)

for those who read german, here is a discussion we had about this in the
VDT forum: http://www.tonmeister.de/forum/viewtopic.php?f=6&t=238&p=817

best,

jörn

-- 
Jörn Nettingsmeier
Lortzingstr. 11, 45128 Essen, Tel. +49 177 7937487
Meister für Veranstaltungstechnik (Bühne/Studio)
Tonmeister VDT
http://stackingdwarves.net
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