Multistage IIR Filter and Parallelized Filtering of Data with Same

摘要

In some embodiments, a multistage filter whose biquad filter stages are combined with latency between the stages, a system (e.g., an audio encoder or decoder) including such a filter, and methods for multistage biquad filtering. In typical embodiments, all biquad filter stages of the filter are operable independently to perform fully parallelized processing of data. In some embodiments, the inventive multistage filter includes a buffer memory, at least two biquad filter stages, and a controller coupled and configured to assert a single stream of instructions to the filter stages. Typically, the multistage filter is configured to perform multistage filtering of a block of input samples in a single processing loop with iteration over a sample index but without iteration over a biquadratic filter stage index.

主权项

1. A multistage filter, including:
a buffer memory; at least two biquad filter stages, including a first biquad filter stage and a subsequent biquad filter stage; and a controller, coupled to the biquad filter stages and configured to assert a single stream of instructions to both the first biquad filter stage and the subsequent biquad filter stage, wherein said first biquad filter stage and said subsequent biquad filter stage operate independently and in parallel in response to the stream of instructions, wherein the first biquad filter stage is coupled to the memory and configured to perform biquadratic filtering on a block of N input samples in response to the stream of instructions to generate intermediate values, and to assert the intermediate values to the memory, wherein the intermediate values include a filtered version of each of at least a subset of the input samples, and wherein the subsequent biquad filter stage is coupled to the memory and configured to perform biquadratic filtering on buffered values retrieved from the memory in response to the stream of instructions to generate a block of output values, wherein the output values include an output value corresponding to each of the input samples in the block of N input samples, and the buffered values include at least some of the intermediate values generated in the first biquad filter stage in response to the block of N input samples.