On Sun, 17 Aug 2014, Will Godfrey wrote: > On Sun, 17 Aug 2014 16:15:58 +0000 > Fons Adriaensen <[email protected]> wrote: >> On Sun, Aug 17, 2014 at 08:24:38AM -0700, Len Ovens wrote: >>> So Allen & Heath uses 127 levels on their top end digital control surfaces, How do they do it? Well they have two different scales: - fader: ((Gain+54)/64)*7f - also used for sends >>> - Gain: ((Gain-10)/55)*7f - this is preamp gain >> Suppose you have *real* faders which have a range of 127 mm. >> That's not far from a typical size on a pro mixer. >> Would you ever adjust them by half a millimeter ? >> 127 steps, provided they are mapped well, and zipper noise >> is avoided by interpolation or filtering, should be enough. >> The real problem is that many SW mixers >> * don't use a good mapping, >> * and don't have any other gain controls. >> The latter may force you to use the fader in a range >> where it has bigger steps. > Well that got me thinking! > Presumably this should be set up as a proper log law, so even if the steps > represent (say) 0.5dB that still gives a control range of over 60dB
I forgot to add: I would think ((Gain+54)/64)*7f uses a lot less CPU time than a real (proper) log. Think 8 fingers (plus thumbs?) fading around 80 steps in a small time. Remember that this calculation has to be done at both ends too and the receiving end also has to deal with doing more calculation on as many as 64 tracks of low latency audio at the same time (amongst other things). Also remember, this is only of use if you are building a control surface (I am) and not buying one where "you get what you get". Add to that, even if you are building your own control surface, do you want to use Yet Another standard that you then have to make middle-ware for so that the SW you are talking to will understand? A&H does supply middle-ware (for OSX) that takes the above values and converts them (both ways) so that their control surface looks to the sw like a Mackie (just about put Wackie) control surface. Talk about lot of computations in you music box! -- Len Ovens www.ovenwerks.net _______________________________________________ Linux-audio-dev mailing list [email protected] http://lists.linuxaudio.org/listinfo/linux-audio-dev
