This routine returns the coefficients of the 𝑁 -coefficient symmetric prototype filter 𝐻 (𝑧 ). The coefficients are normalized to have energy 1/2. When the analysis and synthesis filters are configured as shown above, the overall system has an impulse response with a unity coefficient at a delay of 𝑁 − 1 samples.

The procedure described in the paper above was modified to employ a cautious update during the iteration process – without this modification, the procedure did not converge.

Example

A sample use of QMFDesign is shown below.