Below is an overview of how CELT works:
It may look a bit hairy, but it's actually a relatively simple idea. The four main ideas are:
- We use a lapped transform (here an MDCT) on very short windows (128-256 samples)
- The spectrum is divided in bands and the energy in each band is encoded and kept constant
- We use a time-domain pitch predictor, with frequency-domain gains
- The residual is encoded using a pulse codebook
I'll address each of these (and more) in later posts.