LowLevelSpectralExtractor fails due to a bug in scheduler

[dbogdanov]

import essentia.standard as es
loader = es.EasyLoader(filename='01.wav')
lowLevelSpectralExtractor = es.LowLevelSpectralExtractor(frameSize=2048, hopSize=1024, sampleRate=44100)
audio = loader()
features = lowLevelSpectralExtractor(audio)
...

produces
RuntimeError: In LowLevelSpectralExtractor.compute: VectorInput: internal error: output buffer full

the problem is the bug in the streaming scheduler

[wackou]

Test that pinpoints the issue can be seen here: https://github.com/MTG/essentia/blob/master/test/src/basetest/test_scheduler.cpp

Workaround for now: do not connect the output of an algorithm inside a composite to both a SourceProxy and a Sink from another algorithm inside the same composite

[dbogdanov]

the problem is solved, however there is a warning produced by scheduler:

[ WARNING ] something strange happened in HarmonicPeaks:
[ WARNING ] we are at the end of the stream, but there is a different number of tokens available on the inputs:
[ WARNING ] - HarmonicPeaks::frequencies: 1
[ WARNING ] - HarmonicPeaks::magnitudes: 1
[ WARNING ] - HarmonicPeaks::pitch: 0

which is probably due to the diamond-shape graph (HarmonicPeaks merges back the results of different branches). However, the results seem to be computed ok.