two questions about FFT/IFFT

1) Is it possible to do a non-realtime spectral analysis of a BufferSource
using an AnalyserNode with an OfflineAudioContext?

2) Is it possible for me to use a PeriodicWave to convert an array of
frequency data from the Analyser Node back into a time-domain waveform? It
seems like this isn't possible.

Basically I'd like to come up with a web-based version of the spectral
averaging technique that R Luke DuBois employed on Timelapse... averaging
the spectral content of an entire buffer and then reproducing that content
as a sustained drone. Is that possible yet with the Web Audio API as it
currently exists?

Thanks,
Matt Diamond