I took these waveforms from
AKWF-WaveForms. His README.md mentions:
All samples are resampled From D2+2 (which equals 600 samples) to 256+1 Samples for use on the Teensy 3.1. These audio waveforms have a period of 256 points, plus a 257th point that is a duplicate of the first point. This duplicate is needed because the waveform generator uses linear interpolation between each point and the next point in the waveform.
But indeed the documentation of the Teensy Audio Library mentions:
Configure the waveform to be used with WAVEFORM_ARBITRARY. Array must be an array of 256 samples.
Not sure if the guy behind AKWF-WaveForms used these with something other than the Teensy Audio Libary that had this requirement. A quick glance makes me believe that the (current) Teensy Audio Library does not need this duplicate 257th point, but it won't cause any problem either. In that case I wasted 2 bytes per waveform
There are many more waveforms in that GitHub repo, I just picked a few that seemed interesting.