"Output the same frequency spectrum" - takes some considerable processing! We're usually working in time-domain, not frequency-domain. I think you're saying do a load of processing to fill the gap when you don't have time to do processing?
Audio software often works in the frequency domain too. CPUs have optimized instructions for this (video also uses them).
Also, the article speaks of multithreaded software, where deadlines can be missed because of complicated dependencies. The end stage where you correct for missing samples can work independently of them in its own thread.
