Efficient way of generating sine tones with code?

Additive synthesis of 16k waves is going to be a lot more difficult than subtractive synthesis of white or pink noise.

if you wanted to have that many oscillators at randomized frequencies, amplitudes and phases, you'd need to precalculate a wavetable that, in order to avoid discontinuities, would be so long it would have a latency that would defeat the purpose of the exercise; the only thing you can do is what you're attempting to do now in gen~, or perhaps use oscbank~ if that is suitable

At the risk of revealing my own ignorance, is this a job for fft? I mean, pull a load of sine tones out of a rich sound source, and then manipulated their individual phases etc? Still, 16,000 though ;(

What I do know is that gen~ is 'always on', calculating every sample, so probably unsuited to what you need.

Brendan

Hi,

Thanks for the answers!
I guess I could do some things with FFT, but my application is a little specific and hard to explain, but I have my reasons for wanting to use discrete sines to generate my sound / noise.
16 000 is not an absolute requirement, if I get to around 2000 discrete tones then I would be quite happy.

Is there any way of having part of the gen~ code executing only when a variable have been changed and not on every sample?
Is there a way to use Java script or some of the Java related objects in Max to use code to generate sine waves dynamically?

//Jonatan

Sounds like you have a job for [poly~]. The max number of voices is 1023, so you'll need several [poly~] objects for several thousand sines.

there's no point in reinventing the wheel-- why not use oscbank~, in conjunction with jfc's suggestion to have poly~? gen~ is always 'on'-- it needs to GENerate the audio if you are using it for every sample otherwise you would get silence.

the only way you can "stop" calculations is if you precalculate the audio and then play it back from a buffer-- but then it is no longer dynamic. so the way you've framed the question indicates your needs are contradictory

here's a patch with 500 discrete oscillators which vary freq and amplitude continuously. you can use multisliders to control manually or randomize with metro. you can change 'fundamental" frequency in Hz and range of frequencies in octaves. it only uses 8% cpu on my old laptop, so 2000 or more is easily done-- adapted from ioscbank~ help file

if you dont need to modulate it, why not generate a wavetable offline and write in in a 10000 ms buffer?

If the frequencies are held constant, the suggestion of using the inverse Fourier transform seems spot on. The fourier domain is based on the notion of a signal being made up of a potentially unlimited number of constant sinewaves. A good engineering challenge!

There's also many cheap approximations of sine waves out there, but it's hard to beat a wavetable in practice. And anything over 1000 voices is going to really hammer the audio thread.