The player seems to load fine, but no waveform is displayed. What can I do?
Most of the times, this problem is connected to a newly uploaded file or, in any case, to a file that has never been played back by a WavePlayer instance. When WavePlayer loads a file for the very first time, it needs to analyze its audio content and generates a small peak file where it saves the waveform data. This process only takes place the very first time an audio file is loaded in WavePlayer: once the process is done, the same audio file will always load almost instantaneously.