Digital audio signal filtering mechanism and method

• US 7,016,746 B2
• Filed: 05/16/2002
• Issued: 03/21/2006
• Est. Priority Date: 11/07/1997
• Status: Expired due to Fees

• Current Assignee: Microsoft Technology Licensing LLC (Microsoft Corporation)
• Original Assignee: Microsoft Corporation
• Inventors: Wiser, Philip R., Heringer, LeeAnn, Kearby, Gerry, Rishniw, Leon, Brownell, Jason
• Primary Examiner(s): Pendleton, Brian T.
• Application Number:
  US10/147,746
• Publication Number:
  US 20030009247A1
• Time in Patent Office: 1,405 Days
• Field of Search: 709/217, 709/219, 381/98, 381/103, 381/23, 700/94
• US Class Current: 700/94
• CPC Class Codes: G11B 20/10527 Audio or video recording; Data buffering arrangements G11B20/12 - G11B20/18 take precedence
• CPC Class Codes: G11B 2020/10546 specifically adapted for audio data
• CPC Class Codes: H04S 3/008 in which the audio signals are in digital form, i.e. employing more than two discrete digital channels data reduction aspects thereof based on psychoacoustics G10L19/02
• CPC Class Codes: H04S 7/307 Frequency adjustment, e.g. tone control H04S7/301 takes precedence
• CPC Class Codes: H04S 7/40 Visual indication of stereophonic sound image

Abstract

Essentially all of the processing parameters which control processing of a source audio signal to produce an encoded audio signal are stored in an audio processing profile. Multiple audio processing profiles are stored in a processing profile database such that specific combinations of processing parameters can be retrieved and used at a later time. Audio processing profiles are organized according to specific delivery bandwidths such that a sound engineer can quickly and efficiently encode audio signals for each of a number of distinct delivery media. Synchronized A/B switching during playback of various encoded audio signals allows the sound engineer to detect nuances in the sound characteristics of the various encoded audio signals.

Claims

1. A method for processing an audio signal to produce an encoded audio signal for subsequent decoding and playback of the audio signal, the method comprising:

storing audio signal processing data in a memory of a computer;

retrieving format data from the audio processing data;

producing a format intermediate audio signal from the audio signal in accordance with the retrieved format data;

retrieving sample rate data from the signal processing data;

producing a sample rate converted intermediate audio signal from the format intermediate audio signal in accordance with the sample rate data;

retrieving filtering data from the signal processing data;

producing a filtered intermediate audio signal from the sample rate converted intermediate audio signal in accordance with the filtering data;

retrieving encoding data from the signal processing data;

producing the encoded audio signal from the filtered intermediate audio signal in accordance with the encoding data.

2. The method of claim 1 wherein the step of producing a filtered intermediate audio signal comprises:

filtering the sample rate converted intermediate audio signal using one or more equalization filters, each of which is selected from the group consisting of low shelf, band pass, and high shelf filters and each of which is defined by the filtering data.

3. The method of claim 1 wherein the step of producing a filtered intermediate audio signal comprises:

filtering the sample rate converted intermediate audio signal using one or more dynamic filters, each of which is selected from the group consisting of expander, compressor, and limiter filters and each of which is defined by the filtering data.

4. The method of claim 1 wherein the step of storing comprises the step of:

storing the audio signal processing data as an audio processing profile in a database which includes one or more other audio processing profiles and which is stored in the memory.

5. A computer readable medium useful in association with a computer which includes a processor and a memory, the computer readable medium including computer instructions which are configured to cause the computer to process an audio signal to produce an encoded audio signal for subsequent decoding and playback of the audio signal by performing the steps of:

storing audio signal processing data in a memory of a computer;

retrieving format data from the audio processing data;

producing a format intermediate audio signal from the audio signal in accordance with the retrieved format data;

retrieving sample rate data from the signal processing data;

producing a sample rate converted intermediate audio signal from the format intermediate audio signal in accordance with the sample rate data;

retrieving filtering data from the signal processing data;

producing a filtered intermediate audio signal from the sample rate converted intermediate audio signal in accordance with the filtering data;

retrieving encoding data from the signal processing data;

producing the encoded audio signal from the filtered intermediate audio signal in accordance with the encoding data.

6. The computer readable medium of claim 5 wherein the step of producing a filtered intermediate audio signal comprises:

filtering the sample rate converted intermediate audio signal using one or more equalization filters, each of which is selected from the group consisting of low shelf, band pass, and high shelf filters and each of which is defined by the filtering data.

7. The computer readable medium of claim 5 wherein the step of producing a filtered intermediate audio signal comprises:

filtering the sample rate converted intermediate audio signal using one or more dynamic filters, each of which is selected from the group consisting of expander, compressor, and limiter filters and each of which is defined by the filtering data.

8. The computer readable medium of claim 5 wherein the step of storing comprises the step of:

storing the audio signal processing data as an audio processing profile in a database which includes one or more other audio processing profiles and which is stored in the memory.

9. A computer system comprising:

a processor;

a memory operatively coupled to the processor; and

an audio signal processor which executes in the processor from the memory and which, when executed by the processor, causes the computer to process an audio signal to produce an encoded audio signal for subsequent decoding and playback of the audio signal by performing the steps of;

storing audio signal processing data in a memory of a computer;

retrieving format data from the audio processing data;

producing a format intermediate audio signal from the audio signal in accordance with the retrieved format data;

retrieving sample rate data from the signal processing data;

producing a sample rate converted intermediate audio signal from the format intermediate audio signal in accordance with the sample rate data;

retrieving filtering data from the signal processing data;

producing a filtered intermediate audio signal from the sample rate converted intermediate audio signal in accordance with the filtering data;

retrieving encoding data from the signal processing data;

producing the encoded audio signal from the filtered intermediate audio signal in accordance with the encoding data.

10. The computer system of claim 9 wherein the step of producing a filtered intermediate audio signal comprises:

filtering the sample rate converted intermediate audio signal using one or more equalization filters, each of which is selected from the group consisting of low shelf, band pass, and high shelf filters and each of which is defined by the filtering data.

11. The computer system of claim 9 wherein the step of producing a filtered intermediate audio signal comprises:

filtering the sample rate converted intermediate audio signal using one or more dynamic filters, each of which is selected from the group consisting of expander, compressor, and limiter filters and each of which is defined by the filtering data.

12. The computer system of claim 9 wherein the step of storing comprises the step of:

storing the audio signal processing data as an audio processing profile in a database which includes one or more other audio processing profiles and which is stored in the memory.