(Please add "Audio" to project tags. I find myself unable to do anything but delete existing project tags.)
OS: Windows 7 640but, GPU: GTX 580
OS: Windows 8.1 64-bit, GPU: FeForce CT 735M
Broken: As recently as BuildBot 2.71 5e3e095 to as early as official 2.65a, at least.
Short description of error
A rendered animation containing a speaker with pitch keyframed to go from very low to very high rapidly can usually (but not always, this makes tracking down the causes difficult!) contain a loud, inappropriate click during the transition from low to high pitch.
Attempting to render only the audio (to a .FLAC file) can cause Blender to crash before finishing, producing an incomplete audio file, cut off right before where the click would be, or it can continue, in which case it includes the click and produces a .flac file many, many times larger than it needs to be.
Exact steps for others to reproduce the error
Render the animation in this file:
When I do, I get this:
Render the audio in the file. When I do, I get a 1.2 GB file, which, when saved in Audacity, is only 294 KB.
I have not been able to find any setting (in file export type, in audio device settings, etc.) that reliably gets rid of the clicks. The only method to do so seems to be "avoid rapid increases in pitch." Also note that while my file is at 60 fps, I have observed clicks at 24 fps, as well.
I cannot guarantee that only rapid increases in pitch cause clicks, but I have observed no other situation that does.
Pardon any errors in format or etiquette, phabricator has eaten my bug report twice now and I'm just trying to get it out!