Loading of project hangs non-deterministicly when using "Allpass delay line, noninterpolating"

[michaelgregorius]

Bug Summary

While working on #2068 I have used the attached test project LADSPA-TestProject.zip to check how various LADSPA effects look. From time to time when loading the project LMMS got into an infinite loop, the loading progress stayed at 20% and I had to kill it.

Steps to reproduce

Unfortunately, this issue cannot be reproduced in a deterministic fashion. Just load the project file in LADSPA-TestProject.zip repeatedly until the hang occurs.

Expected behavior

The file loads without problems.

Actual behavior

The loading of the file hangs the whole application.

Results from debugging

Debugging with gdb showed that the problem is caused by the LADSPA plugin "Allpass delay line, noninterpolating" which is contained in the project.

The application hangs in line 66 of allpass_1895.xml. In my case the value of size was 0 and the value of minsize was 2214592512 during the hang. This then results in never ending bit shifting in the main thread.

Affected LMMS versions

Current master at 8b94bd8 and potentially all older versions.