On 20/03/2015 18:58, Alan Wolfe wrote:
your LFO really should go between -1 and 0, you then multiply that value by the number of samples in your buffer (minus 1 if needed, depending on your design and timing in your code), and then subtract that value from your "write index" into the buffer, making sure to handle the case of going negative, where your subtracted offset is greater than your current write index.
I see no need for the LFO not to be bipolar - the idea is to make the midway (zero) position the middle of the (circular) delay buffer, and of course modulation depth must not exceed the extent of the buffer at either end. A slow modulation rate will then apply a respectable vibrato, with pitch deviation approx equal above and below the source.
At least, that is how I have always done it... Richard Dobson -- dupswapdrop -- the music-dsp mailing list and website: subscription info, FAQ, source code archive, list archive, book reviews, dsp links http://music.columbia.edu/cmc/music-dsp http://music.columbia.edu/mailman/listinfo/music-dsp
