Ever heard of the denormalisation problem?
- Upgraded to a P4 processor and got problems with load spikes like never before?.
- Does a certain plugin consume all available CPU power whenever there's NO signal coming in (or out)?.
Denormalisation is an issue with some audio hosts that don't switch off the plugin's audio task when the song is stopped or a track contains silence (or with instruments: no key is pressed while a sound decays).
The problem happens when the CPU (precisely: the floating point unit (FPU) inside of it) detects extremely small numbers and wishes to process them with the same precision as usual. Then it switches into 'denormal' mode which is another way of representing small floating point numbers with the available bit range. Converting between the two states takes a lot of time for the FPU and thus might cause heavy load jumps.
Some algorithm such as delay lines and filters are prone to denormalisation as they work with feedback structures. Here, if an impulse is followed by absolute silence, the resulting signal gets smaller and smaller but in theory, it can never reach zero. In practice, there is an internal threshold of the FPU that switches to denormal mode to carry on processing those small numbers (which might not be of any use for proper operation).
Normalizer is a small plugin that should cancel out those numbers and ensure a trouble-free sequencing of your songs.