Bitcrush

[greg7gkb]

Per #81.

Let me know what you think of it so far :)

[maximecb]

I like that you've added tests.

I actually implemented the bit depth reduction for my own variant and this is the code I had:

// Clamp the input in the [-1, 1] range
inVal = Math.max(Math.min(inVal, 1), -1);

// Map the input to the [0, INT16_MAX] range
let intVal = Math.floor(65535 * (1 + inVal) / 2);

// Drop the bits we don't need
intVal = intVal >> (16 - numBits);

// Convert the value to a floating point number
let maxVal = (1 << numBits) - 1;
let floatVal = intVal / maxVal;
let outVal = floatVal * 2 - 1;

I think we need a bit depth of 32 to signify no bit depth reduction, and the sample rate reduction is probably more useful in terms of how it sounds.

[greg7gkb]

implemented the bit depth reduction for my own variant and this is the code I had:

Very cool. Our approaches are slightly different which I can illustrate when we move to a low number of bits - let's start with 1 bit. At one bit, your algorithm pushes the output to the boundaries at -1 and 1. My algorithm has the +qDelta factor which means it outputs -0.5 and 0.5 (you can see this in the unit tests).

In other words, with 1 bit, your algo chops the space into one segment with outputs at top of bottom. My algo divides the space into two segments and outputs the average level for each segment. I don't know which method would output less error on average, nor which would sound better. Either seems to work.

[greg7gkb]

I just added in sample rate scaling as well - ptal. The feature has a flag useAvg which toggles between using an average value (and thus delay be 'factor' samples) or a held value from the input (no averaging). From the limited audio tests I ran, averaging sounded better but probably also depends on the case at hand.

Unit tests for this still tbd.

[maximecb]

Hello Greg. Sorry for the slow response, got busy with life. I've tried the PR and added comments.

[greg7gkb]

No problem. I'm also busy this week and probably won't have time to resolve until the weekend at best.