CEFT

CEFT

Problems with current implementation and possible solutions

Overlapped FFT not critically sampled

Ideas:

• Use an MDCT instead of the FFT
• Do extrapolation on the input and use a wider FFT. Then optimise the search only for the "real" samples

Non-harmonic signals (i.e. music)

Ideas:

• Sinusoidal prediction
• Use two (or more) pitch periods and choose one for each bin/band/whatever
• Use two (or more) pitch periods at the same time and use energy conservation to keep everything stable.

Sparse spectrum

Ideas:

• Use a "rotation matrix"
• Prediction from lower frequencies