I'm trying to apply the sine-wave Tremolo effect to a few minutes of audio I have, and I'd like to set the Frequency (Hz) to be 0.25 to achieve 15 periods per minute. However, the UI of the Tremolo parameters popup seems to disregard anything more accurate than tenth of a Hz.
E.g. I can set it to 0.2 Hz to have 12 cycles/min, or 0.3 Hz to have 18 cycles/min, but manually entering 0.25 in the text-field besides seems to be ignored.
Is there a way I can still achieve a 0.25 Hz Tremolo effect within Audacity somehow?
Or if not, is there some other free and/or open source software that runs on Linux or on the web that can do the trick? Command-line solutions also interest me if no GUI-based solutions are available.
Or if not, is there some proprietary and/or closed software to achieve this effect?