Lookup~ table and signal distortion: waveshaping

If a sample playback object doesn’t follow through linearly from top to bottom into a sample memory buffer it will create odd sounds: it can reverse the sound, playing faster and therefore at a different pitch, skipping through, with the risk of creating clicks, noises, most of the unwanted.

However, this can be actually what we really want, if distorting a signal is our goal.

One famous way of creating distortion is to waveshape a sound. A playback object reads into a sample buffer accordingly to an order of samples that has nothing to do with the actual samples stored in the memory. The resulting audio output then takes all sort of audio distortions, which sound cool in the end. Another is the clip~ distortion, which is literally, cutting the shape of a signal,  by pushing it out of the soudncard boundaries.

Digital distrotion effects cannot be compared to the distortions applied via physical signal paths (from instrument, through amplifier, to the ears) but can simulate quite well at least certain effects.

[Article about THe fuzz effect]

Signal and buffers can be all mixed-up. A sample playback object (like groove~ or play~) take a sample from a memory buffer and reads through it, returning amplitudes values over time.

If the amplitude values order of a sample gets mixed up, then the resulting played back signal gets distortions, extra-harmonics, clips and many other artefacts, that lovers of distortion really like.

The clip~ object takes an incoming signal but has a reduced dynamic range. The signal by passing through it loses some of its data which is not readjusted at the output but left as it is: cracks, clicks and all sorts of noise start appearing in the signal, with quite likeable distrotion effect.

[picture samples]

compare the two waves before, to the left the original sample, to the right the same portion of the sample passing through a -0224-0.18 clip cut (range reduce from -1-1 to -0.24-0.2)

When a sample playback object like play~ or groove~ doesn;t follow the expected order of samples in the buffer memory it will play one after the other unrelated sampled amplitudes. For each of them at each bit there will be unpredictable skips in the amplitudes, which creates noise.

the lookup~ object takes an incomng signal but follows a lookup table to instruct the playback of the signal. This results in distortion.