Slide 9 of 22

Notes:

• The advantage of this closed-loop technique is that the residuals that go into the design of the quantizer are based on decoded samples and thus the statistics are much closer now to those of an actual coder.

• Unfortunately, the design is unstable. The training set changes from one iteration to the next in an unpredictable manner and accumulation of errors from one frame to the next causes large deviations in the training stage. In fact, there are no guarantees that iterating further will improve the design.