US 2015/0310872 A1Published application

Multistage IIR Filter and Parallelized Filtering of Data with Same

AssigneeDolby Laboratories Licensing Corporation

InventorKhushbu P. Rathi

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Abstract

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.

Claims17

Dependent claims

An audio encoder configured to generate encoded audio data in response to input audio data, said encoder including at least one multistage filter coupled and configured to filter the audio data, wherein the multistage filter includes:

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.

3 more elements

A method for encoding audio data to generate encoded audio data, including by performing multistage filtering on a block of N audio data samples, wherein the multistage filtering includes the steps of:

(a) performing a first biquadratic filtering operation on the block of N samples to generate intermediate values, and asserting the intermediate values to a buffer memory, wherein the intermediate values include a filtered version of each of at least a subset of the N samples;
and
(b) performing a second biquadratic filtering operation on buffered values retrieved from the memory, to generate a block of output values, wherein the output values include an output value corresponding to each of the samples in the block of N samples, a different subset of the buffered values is retrieved and filtered to generate the output value corresponding to each of the samples in the block, and each said subset of the buffered values includes at least two of the intermediate values generated during performance of step (a) which are retrieved from the memory after residing in said memory for different latency times,
wherein steps (a) and (b) are performed in response to a single stream of instructions, such that steps (a) and (b) are performed independently and in parallel in response to the single stream of instructions.

1 more element

Dependencies are inferred from the claim text.

Facts

Application: 14/791,620Filed 6 Jul 2015
Priority: 10 May 2012
Published: 29 Oct 2015
Term ends: Not estimatedThe source records don’t support an estimate.

Classification4 codes

G10L 19/26
Using predictive techniques: pre-filtering or post-filtering
H03H 17/04
Frequency selective networks: recursive filters
G10L
Speech analysis techniques or speech synthesis
H03H
Impedance networks

Family

Application61/645,291Us provisional application · filed 10 May 2012
Application14/058,498Continuation · filed 21 Oct 2013
Application14/791,620Continuation
US 2014/0046673 A1Published application
US 9,076,449 B2Related patent
US 9,324,335 B2Related patent
US 2015/0310872 A1This patent

From the US filing history. Foreign family members aren’t listed.