Basic Granulation

An example of basic audio granulation, where short audio. Grains are extracted and reassembled to create a texture. It focuses on randomizing parameters like grain size and density, selecting source material, and layering grains to produce evolving, complex sonic results.

basic_granulation.bell

## Import sound to perform granulation on
$buf = importaudio('singing.wav');
## Retrieve the duration of the imported sound
$bufdur = $buf.getkey('duration');
## Define the total duration for the granular procesing output
$totdur = 8000;
## Initialize the onset time for grains
$onset = 0;
## Define a breakpoint function (BPF) to control grain playback positions
$readbpf = [0 0 0] [1 1 0];
## Set the duration of each grain in milliseconds
$graindur = 100;
## Compute the maximum possible offset within the buffer, ensuring grains do not exceed the buffer duration
$maxoffset = $bufdur - $graindur;
## Define grain windowing process
$win = window();
## Set a jitter value for randomizing the grain start times
$jitter = 1000;
## Define the overlap factor for grain scheduling
$overlap = 4;
## Iterate until the onset time reaches the total duration
while $onset < $totdur do (
    ## Normalize the current onset time to a [0,1] range
    $nt = $onset / $totdur;
    ## Determine the grain offset using the breakpoint function (BPF)
    $offset = samplebpf($readbpf, $nt) * $maxoffset;
    ## Apply random jitter to the grain offset
    $offsetvar = rand(-1, 1) * $jitter;
    ## Clamp the offset value within valid buffer boundaries
    $offset = max(0, min($maxoffset, $offset + $offsetvar));
    ## Create a grain with specified duration and computed offset
    $grain = $buf.setkey('duration', $graindur).setkey('offset', $offset);
    ## Apply windowing and transcribe the grain with randomized parameters
    $grain.process($win).transcribe(
        ## Introduce slight randomness to onset times
        @onset $onset + rand(-1, 1) * $graindur
        ## Randomize stereo placement
        @pan rand() 
        ## Randomize amplitude between 0.5 and 1
        @gain rand(0.5, 1) 
    );
    ## Increment onset time based on overlap factor
    $onset += $graindur / $overlap
);
## Render the audio output and play the result
render(@play 1)