For the record, I think this is a terrible idea. However, the way I'd do it if needed: keep two or the most recent good buffers. When you need to synthesize, s

For the record, I think this is a terrible idea. However, the way I'd do it if needed: keep two or the most recent good buffers. When you need to synthesize, start running a phase vocoder based on the hop between those two. You get frozen sinusoids and some random noise for the bins that don't have one, and almost no cpu use on the happy path of no underruns. Still, don't do it :)