FFT
Fast Fourier Transform. A fast algorithm for performing a discrete Fourier transform (an orthogonal transform).


Filterbank
A set of band-pass filters covering the entire audio frequency range.


Flag
A variable which can take one of only two values.


Forbidden
The term forbidden when used in the clauses defining the coded bitstream indicates that the value shall never be used. This is usually to avoid emulation of start codes.


Forward compatibility
A new coding standard is forward compatible with an existing coding standard if new decoders (designed to operate with the new coding standard) continue to be able to decode bitstreams of the existing coding standard.


Fs
Sampling frequency.