On March 12, 2013 03:08:18 PM Tim E. Real wrote: > On March 12, 2013 08:41:01 PM you wrote: > > On 03/12/2013 04:23 PM, Tim E. Real wrote: > > > Hi, I need some advice, clear up some confusion: > > > > > > I noticed our app uses this pan formula: > > > vol_L = volume * (1.0 - pan); > > > vol_R = volume * (1.0 + pan); > > > > > > where volume is the fader value, pan is the pan knob value > > > which ranges between -1.0 and 1.0, and vol_L and vol_R are the > > > factors to be applied to the data when sending a mono signal > > > to a stereo bus. > > > > > > When pan is center, 100% of the signal is sent to L and R. > > > At pan extremities, the signal is boosted by 3dB. > > > > > > But according to [1], we should be using a Pan Law [2], > > > > > > where pan center is around 3dB to 6dB down and pan > > > extremities is full signal. > > > > > > So I want to change how we mix mono -> stereo and use > > > > > > true Pan Law. I could add a Pan Law selector, seems like it > > > might be useful for various studio acoustics. > > > > > > Then I noticed we use the same formula above to apply 'balance' > > > > > > (using the same pan knob) when sending a stereo signal to > > > a stereo bus. > > > > > > But according to [3] we should be using a true balance control, not > > > those > > > > > > same pan factors above. And according to [1]: > > > "Note that mixers which have stereo input channels controlled by a > > > single > > > > > > pan pot are in fact using the balance control architecture in those > > > channels, not pan control." > > > > > > So I want to change how we mix stereo -> stereo and use true balance. > > > > > > But then I checked some other apps to see what they do. > > > In an unofficial test I noticed that QTractor seems to do the same > > > thing, > > > > > > that is, when pan is adjusted on a stereo track, one meter goes up > > > while > > > the other goes down. RG seems not to have stereo meters and Ardour > > > I couldn't seem to make pan affect the meters, I will try some more. > > > > > > My questions: > > > > > > Is the pan formula above popular? > > > > > > What is the consensus on stereo balance - use a Pan Law, being the > > > > > > formula above or otherwise, or use a true balance? > > > > > > What should I do in the remaining case sending a stereo signal to a mono > > > bus? If I am using a Pan Law as balance, the two signals will have > > > already been> > > > > > > attenuated at pan center so I could simply sum the two channels > > > together. > > > > > > But if instead I use true balance, at center the two signals are 100%. > > > So should I attenuate the signals before summing them to a mono bus? > > > Currently as our pan formula above shows, there would be no attenuation. > > > > you are right - it should attenuate in the middle and gain increase as > > you move. i hate balance controls because you can't move the image > > around the panorama. if you have a stereo piano sample for example, you > > need to move all the "sample data" around the sound stage - not hear an > > amplified L channel and an attenuated R channel which is the balance > > model. Balance is for home stereo's. Pan is for grown ups :) > > OK just to be clear I was not implying that the given pan formula > would be used to do a true 'stereo pan', just that the formula would be > used to adjust stereo 'balance' giving almost the same results as a true > stereo balance, but slightly different levels, but not a true 'stereo pan'. > > But having said that, yes I'm wondering about a true 'stereo pan' feature. > How would such a feature work? > I imagine that if for example if there is sound exclusively on the L > channel, and 'stereo pan' is at center then moved all the way to the right, > the sound that was exclusively on the L channel now moves to the exact > center? That is, all the sound in the stereo field now moves 90 degrees to > the right? It means you'd never be able to completely move an exclusive > sound which was strictly on L, all the way to the right.
Ah, the answer might be an 'expanded' pan range of -180 to +180 degrees instead of the normal -90 to +90. That way something all the way on L could be moved all the way to R. Right? Tim. > > Does that sound correct Geoff? > I can easily implement a true 'stereo pan', given some rules. > Just, now I'd have to give the user the option of using either pan or > balance, complicating things a wee bit more, but probably nothing an > additional small pushbutton or two couldn't fix. > > Thanks. > Tim. _______________________________________________ Linux-audio-dev mailing list [email protected] http://lists.linuxaudio.org/listinfo/linux-audio-dev
