Strict convolution with fixed kernel which can be updated using a trigger signal. There is a linear crossfade between the buffers upon change.
See Steven W Smith, The Scientist and Engineer's Guide to Digital Signal Processing: chapter 18 - http://www.dspguide.com/ch18.htm
buffer index for the fixed kernel, may be modulated in combination with the trigger
update the kernel on a change from <=0 to >0
size of FFT frame, must be a power of two (512, 1024, 2048, 4096 are standard choices). Convolution uses twice this number internally. Note that the convolution gets progressively more expensive to run for higher powers! The maximum value you can use is 2^16=16384. (This upper limit is half of "SC_FFT_MAXSIZE" defined in the SC source code.) Larger convolutions than this can be done using PartConv.
The number of periods over which a crossfade is made. The default is 1. This must be an integer.