Automatic correction of power spectral balance in audio source material

• US 6,341,166 B1
• Filed: 03/12/1997
• Issued: 01/22/2002
• Est. Priority Date: 03/12/1997
• Status: Expired due to Term

• Current Assignee: Avago Technologies General IP PTE Limited (Broadcom, Inc.)
• Original Assignee: LSI Logic Corporation (Broadcom, Inc.)
• Inventors: Basel, Peter L.
• Primary Examiner(s): Lee, Ping
• Application Number:
  US08/820,370
• Time in Patent Office: 1,777 Days
• Field of Search: 381/98-103, 381/61, 381/63, 333/28.T, 333/28.R
• US Class Current: 381/103
• CPC Class Codes: H03G 5/005 of digital signals
• CPC Class Codes: H04S 7/307 Frequency adjustment, e.g. tone control H04S7/301 takes precedence

Abstract

An audio system that automatically corrects for variations in spectral balance in audio source material. The audio system comprises a power spectrum analyzer and a source correction equalizer unit coupled to receive an audio input signal, and an index control unit coupled to a spectral balance correction data memory. A reference spectral balance may initially be established by playing a reference source medium with desired sound attributes. The power spectrum analyzer characterizes the spectral balance of the reference source medium, storing the results in non-volatile memory. When a particular source medium is played for the first time, the index control unit reads an identifying parameter from the particular source medium. Because there is no entry for the identifying parameter in spectral balance correction data memory, the particular source medium has not been previously played on the audio system. The particular source medium is then played in its entirety, with the index control unit signaling the power spectrum analyzer to characterize the spectral balance of the particular source medium. When the particular source medium is finished playing, an equalizer settings compute unit compares the reference spectral balance and the spectral balance for the particular source medium and calculates equalizer correction settings, which are then stored in spectral balance correction data memory. These settings can be used to adjust the spectral balance of the particular source medium to match that of the reference source medium. When the particular source medium is subsequently played, the identifying parameter may be used to recall these desired equalizer settings.

Claims

1. A method for equalizing an audio input signal provided from an audio source storage medium, comprising:

characterizing a spectral balance corresponding to a reference audio source storage medium, thereby establishing a reference spectral balance;

storing said reference spectral balance to a reference memory location;

characterizing a spectral balance corresponding to said audio source storage medium, thereby establishing a current source spectral balance;

reading a parameter from said audio source storage medium;

using said parameter to index into a given memory location which stores particular equalizer settings;

controlling an equalizer unit in accordance with said particular equalizer settings, wherein said equalizer unit is configured to adjust the magnitude of selected frequency ranges of said audio input signal in accordance with said particular equalizer settings, thereby producing an audio output signal; and

calculating said particular equalizer settings in response to comparing a particular one of a plurality of reference spectral balances and said current source spectral balance, wherein said particular one of said plurality of reference spectral balances is user-selectable, and wherein said plurality of reference spectral balances is established by characterizing a plurality of spectral balances each corresponding to one of a plurality of reference audio source storage media, and wherein said plurality of reference spectral balances are stored in a plurality of reference memory locations, and wherein said plurality of reference memory locations are non-volatile.

2. The method for equalizing an audio input signal provided from an audio source storage medium as recited in claim 1, wherein said audio output signal exhibits a desired spectral balance.

3. The method for equalizing an audio input signal provided from an audio source storage medium as recited in claim 1, wherein said parameter identifies said audio source storage medium.

4. The method for equalizing an audio input signal provided from an audio source storage medium as recited in claim 1, wherein said calculating said particular equalizer settings is performed by homomorphic signal processing.

5. The method for equalizing an audio input signal provided from an audio source storage medium as recited in claim 1, further comprising storing said particular equalizer settings to said given memory location.

6. The method for equalizing an audio input signal provided from an audio source storage medium as recited in claim 5, wherein said given memory location is non-volatile.

7. The method for equalizing an audio input signal provided from an audio source storage medium as recited in claim 5, wherein said storing said particular equalizer settings to said given memory location is performed prior to said reading said parameter from said audio source storage medium.

8. The method for equalizing an audio input signal provided from an audio source storage medium as recited in claim 1, further comprising conveying said audio output signal to a second equalizer unit.

9. The method for equalizing an audio input signal provided from an audio source storage medium as recited in claim 8, further comprising controlling said second equalizer unit in accordance with user-defined settings, wherein said second equalizer unit is configured to attenuate selected frequency ranges of said audio output signal in accordance with said user-defined settings.

10. The method for equalizing an audio input signal provided from an audio source storage medium as recited in claim 8, further comprising controlling said second equalizer unit in accordance with a particular one of a plurality of user-defined settings, wherein said particular one of said plurality of user-defined settings is user-selectable, and wherein said second equalizer unit is configured to attenuate selected frequency ranges of said audio output signal in accordance with said particular one of said plurality of user-defined settings.

11. An audio system configured to equalize an audio input signal provided from an audio source storage medium, comprising:

a processing unit coupled to receive said audio input signal;

a memory coupled to said processing unit, wherein said memory includes a given memory location which stores particular equalizer settings; and

an equalizer unit coupled to said processing unit, wherein said equalizer unit is configured to receive said audio input signal;

wherein said processing unit is configured to read a parameter which identifies said audio source storage medium from said audio source storage medium, and wherein said processing unit is configured to use said parameter to index into said given memory location and wherein said processing unit is further configured to control said equalizer unit in accordance with said particular equalizer settings, wherein said equalizer unit is configured to adjust the magnitude of selected frequency ranges of said audio input signal, thereby producing an audio output signal;

wherein said processing unit is further configured to characterize a spectral balance corresponding to a reference audio source storage medium, thereby establishing a reference spectral balance;

wherein said processing unit is further configured to store said reference spectral balance to a reference memory location;

wherein said processing unit is further configured to characterize a spectral balance corresponding to said audio source storage medium, thereby establishing a current source spectral balance; and

wherein said processing unit is further configured to calculate said particular equalizer settings in response to comparing a particular one of a plurality of reference spectral balances and said current source spectral balance, wherein said particular one of said plurality of reference spectral balances is user-selectable, and wherein said plurality of reference spectral balances is established by characterizing a plurality of spectral balances each corresponding to one of a plurality of reference audio source storage media, and wherein said plurality of reference spectral balances are stored in a plurality of reference memory locations, and wherein said plurality of reference memory locations are non-volatile.

12. An audio system configured to equalize an audio input signal provided from an audio source storage medium as recited in claim 11, wherein said audio output signal exhibits a desired spectral balance.

13. An audio system configured to equalize an audio input signal provided from an audio source storage medium as recited in claim 11, wherein said processing unit calculates said particular equalizer settings by homomorphic signal processing.

14. An audio system configured to equalize an audio input signal provided from an audio source storage medium as recited in claim 11, wherein said processing unit is further configured to store said particular equalizer settings to said given memory location.

15. An audio system configured to equalize an audio input signal provided from an audio source storage medium as recited in claim 14, wherein said given memory location is non-volatile.

16. An audio system configured to equalize an audio input signal provided from an audio source storage medium as recited in claim 14, wherein said processing unit storing said particular equalizer settings to said given memory location is performed prior to said processing unit reading said parameter from said audio source storage medium.

17. An audio system configured to equalize an audio input signal provided from an audio source storage medium as recited in claim 11, further comprising a second equalizer unit coupled to receive said audio output signal as an input.

18. An audio system configured to equalize an audio input signal provided from an audio source storage medium as recited in claim 17, wherein said processing unit is further configured to control said second equalizer unit in accordance with user-defined settings, and wherein said second equalizer unit is configured to attenuate selected frequency ranges of said audio output signal in accordance with said user-defined settings.

19. An audio system configured to equalize an audio input signal provided from an audio source storage medium as recited in claim 17, wherein said processing unit is further configured to control said second equalizer unit in accordance with a particular one of a plurality of user-defined settings, wherein said particular one of said plurality of user-defined settings is user-selectable, and wherein said second equalizer unit is configured to attenuate selected frequency ranges of said audio output signal in accordance with said particular one of said plurality of user-defined settings.

20. An audio system configured to equalize an audio input signal provided from an audio source storage medium, comprising:

an index control unit configured to read a parameter which identifies said audio source storage medium from said audio source storage medium;

a spectral balance correction memory coupled to said index control unit, wherein said spectral balance correction memory stores particular equalizer settings;

a source correction equalization unit coupled to said spectral balance correction memory, wherein said source correction equalization unit is coupled to receive said audio input signal and said particular equalizer settings, and wherein said source correction equalization unit is further configured to adjust the magnitude of selected frequency ranges of said audio input signal, thereby establishing an audio output signal;

a power spectrum analyzer, wherein said power spectrum analyzer is configured to characterize a spectral balance corresponding to a reference audio source storage medium, thereby establishing a reference spectral balance;

a reference spectral balance memory, wherein said power spectrum analyzer is further configured to store said reference spectral balance to said reference spectral balance memory;

a current source spectral balance memory, wherein said power spectrum analyzer is further configured to characterize a spectral balance corresponding to said audio source storage medium, thereby establishing a current source spectral balance, and wherein said power spectrum analyzer is configured to store said current source spectral balance to said current source spectral balance memory; and

an equalizer setting compute unit configured to calculate said particular equalizer settings in response to comparing a particular one of a plurality of reference spectral balances and said current source spectral balance, wherein said particular one of said plurality of reference spectral balances is user-selectable, and wherein said plurality of reference spectral balances is established by characterizing a plurality of spectral balances each corresponding to one of a plurality of reference audio source storage media, and wherein said plurality of reference spectral balances are stored in a plurality of reference memory locations, and wherein said plurality of reference memory locations are non-volatile.

21. An audio system configured to equalize an audio input signal provided from an audio source storage medium as recited in claim 20, wherein said audio output signal exhibits a desired spectral balance.

22. An audio system configured to equalize an audio input signal provided from an audio source storage medium as recited in claim 20, wherein said equalizer setting compute unit calculates said particular equalizer settings by homomorphic signal processing.

23. An audio system configured to equalize an audio input signal provided from an audio source storage medium as recited in claim 20, wherein said equalizer setting compute unit is further configured to store said particular equalizer settings to said spectral balance correction memory.

24. An audio system configured to equalize an audio input signal provided from an audio source storage medium as recited in claim 23, wherein said equalizer setting compute unit storing said particular equalizer settings to said spectral balance correction memory is performed prior to said index control unit reading said parameter from said audio source storage medium.

25. An audio system configured to equalize an audio input signal provided from an audio source storage medium as recited in claim 20, further comprising a listener correction equalization unit coupled to receive said audio output signal as an input.

26. An audio system configured to equalize an audio input signal provided from an audio source storage medium as recited in claim 25, wherein said listener correction equalization unit attenuates selected frequency ranges of said audio output signal in accordance with user-defined settings.

27. An audio system configured to equalize an audio input signal provided from an audio source storage medium as recited in claim 25, wherein said processing unit is further configured to control said listener correction equalization unit in accordance with a particular one of a plurality of user-defined settings, wherein said particular one of said plurality of user-defined settings is user-selectable, and wherein said listener correction equalization unit is configured to attenuate selected frequency ranges of said audio output signal in accordance with said particular one of said plurality of user-defined settings.

28. A method for equalizing an audio input signal provided from an audio source storage medium, comprising:

characterizing a spectral balance corresponding to a reference audio source storage medium, thereby establishing a reference spectral balance, wherein said reference spectral balance is user-selectable;

storing said reference spectral balance within a reference non-volatile memory location;

characterizing a spectral balance corresponding to said audio input signal, thereby establishing a current source spectral balance;

calculating a particular equalizer setting in response to comparing said reference spectral balance and said current source spectral balance;

storing said particular equalizer setting into a given memory location;

reading a parameter from said audio source storage medium;

using said parameter to index into said given memory location which stores said particular equalizer setting; and

controlling an equalizer unit in accordance with said particular equalizer setting, wherein said equalizer unit is configured to adjust the magnitude of selected frequency ranges of said audio input signal in accordance with said particular equalizer settings, thereby producing an audio output signal.

29. The method for equalizing an audio input signal provided from an audio source storage medium as recited in claim 28, wherein said calculating said particular equalizer setting is performed by homomorphic signal processing.

30. The method for equalizing an audio input signal provided from an audio source storage medium as recited in claim 28, wherein said given memory location is non-volatile.

31. An audio system configured to equalize an audio input signal provided from an audio storage medium, comprising:

a processing unit coupled to receive said audio input signal;

a memory coupled to said processing unit, wherein said memory includes a given memory location which stores a particular equalizer setting; and

an equalizer unit coupled to said processing unit, wherein said equalizer unit is configured to receive said audio input signal;

wherein said processing unit is configured to read a parameter from said audio source storage medium and to use said parameter to index into said given memory location, and wherein said processing unit is further configured to control said equalizer unit in accordance with said particular equalizer setting to thereby adjust the magnitude of selected frequency ranges of said audio input signal to produce an audio output signal;

wherein said processing unit is further configured to characterize a spectral balance corresponding to a reference audio source storage medium, thereby establishing a reference spectral balance, wherein said reference spectral balance is user-selectable;

wherein said processing unit is further configured to store said reference spectral balance to a reference memory location;

wherein said processing unit is further configured to characterize a spectral balance corresponding to said audio input signal, thereby establishing a current source spectral balance; and

wherein said processing unit is further configured to calculate said particular equalizer setting by comparing said reference spectral balance and said current source spectral balance, and to store said particular equalizer setting within said given memory location.

32. An audio system configured to equalize an audio input signal provided from an audio source storage medium as recited in claim 31, wherein said processing unit calculates said particular equalizer setting by homomorphic signal processing.

33. An audio system configured to equalize an audio input signal provided from an audio source storage medium as recited in claim 31, wherein said given memory location is non-volatile.