Possible bug/limit in hum remover filter


I’m having trouble using the hum filter. The recording is 2 channel and 2.5 hrs long, and I’m trying to take out hum with a setting of 4 odd, 1 even harmonics, default 10% sensitivity. At almost exactly halfway through (on the progress bar), the process freezes, and I get “Audacity failed to read from a file from D:” (D: is my temp disk and has 40G spare).

If I run using the debug button, it does the same with an empty dialog box at the failure point. The machine is Win 7 running latest 2.2.1 and has 12G RAM. I have re-created a project from scratch, reimported the source file with the same results. Other hum remover settings result in same.

As a workaround I can perform the filtering if I do it in 2 separate passes, start → halfway and halfway → end, so it looks like some kind of capacity limitation.

This is a problem that affects a lot of Nyquist plug-ins (but not all).
Unlike built-in effects, Nyquist effects do not have arbitrary access to the audio data - they can read a track selection once, from the start of the selection to the end of the selection. Some processes, notable those that require analysis before the effect is applied, need to access the data more than once, and the only way that they can do that is to retain the data in RAM. However, because Nyquist is running in a 32-bit environment, the limit to the amount of data that may be addressed in RAM is 2GB. Thus many Nyquist effects break beyond an hour and a bit.

I’m a bit surprised that this problem occurs with a filter plug-in. Where can I find that plug-in?