Enhancement Summary

Plotting the audio waveform is currently done in SampleBuffer::visualize. Creating and updating the waveform plot is very unresponsive. You can observe this for example when you load a whole track in the AudioFileProcessor and turn the amplification knob.
Furthermore, every nth sample is currently plotted. In my opinion, this method of "compressing" the information in the actual waveform makes limited sense only. The maximum or RMS of the samples per pixel should be used instead, like in audacity.

Justification

This performance issue can be observed especially for longer samples (>2min) in the following situations:

1. Loading a sample: You have to keep the mouse pressed for 15s+ until you can place the sample in the timeline
2. Moving the amplification knob in the AudioFileProcessor

If this feature is wanted I can try to put something together after the refactor.