Title:
INFINITE IMPULSE RESPONSE FILTER FOR 3D SOUND WITH TAP DELAY LINEINITIALIZATION
Document Type and Number:
WIPO Patent Application WO1999009648
Kind Code:
A3
Abstract:
An audio processing system is used to process digital audio signals that represent sound emanating from a source that is moving through three dimensional space. The audio processing system has a filter unit that employs infinite impulse response (IIR) filters to filter the audio signals. The IIR filters have filter coefficients that change when the sound source is stationary or moves from one location to the next in the 3D space. To minimize the transient response following a coefficient change, the filter unit initializes elements in the tap delay lines of the IIR filters to non-zero values. In one implementation, the tap delay line elements are changed to a set of predetermined non-zero values. In another implementation, the tap delay line elements are initialized to the final values produced by the filter for the previous sound source location. A third implementation is to initialize the tap delay line elements to values that are a function of the new coefficients and the first sample of data at the new location. Yet another implementation is to initialize the tap delay line elements to steady state values produced in response to a step input.
Inventors:
STOKES JACK W III (US)
Application Number:
PCT/US1998/016743
Publication Date:
July 11, 2002
Filing Date:
August 12, 1998
Export Citation:
Assignee:
MICROSOFT CORP (US)
International Classes:
H04S1/00; H03H17/02; H03H17/04; (IPC1-7): H03H17/02
Foreign References:
| US5404406A | 1995-04-04 | |||
| EP0326672A1 | 1989-08-09 |
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