Hi,
If your question is with respect to the complexity and the compression then here are the standards that are latest.
Audio:
AC3, Variation of CSACELP(ITU-TG.729) for whole of audio.
Speech:
CSACELP(ITU-TG.729) the best wrt both quality & compression, MELP avg quality but greater compression.
SMV coder for 3GPP2. Select mode vocoder. Developed by Conexcent and other companies.
Mpeg4 audio, which includes a 2 kbps low bit rate speech coding developed by Sony. It uses hormonic coders for voiced speech and CELP for unvoiced speech.
Hi,dinolin:
Do you have some sigma delta document ??such as
1.Oversampling Delta-Sigma Data Converters : Theory, Design, and Simulation
by James C. Candy (Editor), Gabor C. Temes (Editor)
2.Understanding Delta-Sigma Data Converters
by Richard Schreier, Gabor C. Temes
3.Delta-Sigma Modulators: Modeling, Design and Applications
by George I. Bourdopoulos, Aristodemos Pnevmatikakis, Vassilis Anastassopoulos, Theodore L. Deliyannis