FFmpeg 3.3.9
abuffer
Buffer audio frames, and make them available to the filter chain.
aevalsrc
Generate an audio signal specified by an expression.
anullsrc
The null audio source, return unprocessed audio frames.
flite
Synthesize a voice utterance using the libflite library.
anoisesrc
Generate a noise audio signal.
sine
Generate an audio signal made of a sine wave with amplitude 1/8.