Sound processing system with degraded signal optimization

• US 20030039365A1
• Filed: 07/31/2002
• Published: 02/27/2003
• Est. Priority Date: 05/07/2001
• Status: Active Grant

• Current Assignee: Harman International Industries Incorporated (Samsung Electronics Co. Ltd.)
• Original Assignee: Harman International Industries Incorporated (Samsung Electronics Co. Ltd.)
• Inventors: House, William, Eid, Bradley
• Granted Patent: US 7,177,432 B2
• Time in Patent Office: Days
• US Class Current: 381/27
• CPC Class Codes: H04R 2499/13 Acoustic transducers and sound field adaptation in vehicles
• CPC Class Codes: H04S 3/02 of the matrix type, i.e. in which input signals are combined algebraically, e.g. after having been phase shifted with respect to each other
• CPC Class Codes: H04S 5/00 Pseudo-stereo systems, e.g. in which additional channel signals are derived from monophonic signals by means of phase shifting, time delay or reverberation
• CPC Class Codes: H04S 5/005 of the pseudo five- or more-channel type, e.g. virtual surround
• CPC Class Codes: H04S 7/305 Electronic adaptation of stereophonic audio signals to reverberation of the listening space H04S7/301 takes precedence

Abstract

A sound processing system adaptively mixes active matrix decoding and passive matrix processing of incoming audio signals. Mixed output signals are generated with active matrix decoding where the audio signals are stereo. Mixed output signals are generated with passive matrix processing where the audio signals are monaural. The sound processing system reduces the degree of active matrix decoding in the mixed output signals where the incoming audio signals are stereo and monaural. The sound processing system also generates virtual stereo signals from incoming audio signals having monaural signals. Mixed output signals are generated of the virtual stereo signals using active matrix decoding.

Claims

1. A sound processing system, comprising:

a head unit;

a decoder connected to the head unit, where the decoder generates decoded signals in response to audio signals from the head unit; and

a crossbar matrix mixer connected to the head unit and to the decoder, the crossbar matrix mixer to receive audio signals from the head unit, the crossbar matrix mixer to receive the multiple decoded signals from the decoder;

where the crossbar matrix mixer generates mixed output signals in response to the audio signals and the multiple decoded signals;

where the mixed output signals comprise active matrix decoded signals when the audio signals comprise a stereo signal, and

where the mixed output signals comprise passive matrix processed signals when the audio signals comprise a monaural signal.

2. The sound processing system according to claim 1, where the degree of active matrix decoding is reduced in the mixed output signals when the audio signals comprise stereo and monaural signals.

3. The sound processing system according to claim 1, where the mixed output signals comprise passive matrix processed signals when the audio signals comprise stereo and monaural signals.

4. The sound processing system according to claim 1, where the audio signals comprise digital signals.

5. The sound processing system according to claim 1, further comprising a secondary source connected to the crossbar matrix mixer.

6. The sound processing system according to claim 1, where the decoded signals comprise five decoded signals.

7. The sound processing system according to claim 6, comprising a decoded signal for a subwoofer.

8. The sound processing system according to claim 1, where the decoded signals comprise seven decoded signals.

9. The sound processing system according to claim 8, comprising a decoded signal for a subwoofer.

10. The sound processing system according to claim 1, where the decoder comprises a discrete decoder.

11. The sound processing system according to claim 1, where the decoder comprises a LOGIC 70 decoder.

12. The sound processing system according to claim 1, where the mixed output signals comprise at least two summed signals.

13. The sound processing system according to claim 1, where the mixed output signals comprise at least one left signal, at least one right signal, and a center signal.

14. The sound processing system according to claim 13,

where the at least one left signal comprises at least one of a left front signal, a left surround signal, and left rear signal;

and

where the at least one right signal comprises at least one of a right front signal, a right surround signal, and a right rear signal.

15. The sound processing system according to claim 1, where the head unit comprises a left channel and a right channel.

16. The sound processing system according to claim 15, further comprising:

a first analog to digital converter (ADC) connected to the left channel, the decoder, and the crossbar matrix mixer; and

a second analog to digital converter (ADC) connected to the right channel, the decoder, and the crossbar matrix mixer.

17. The sound processing system according to claim 1,

where an ambiance signal is added to the audio signals;

where the decoder generates the decoded signals in response to the ambiance and audio signals; and

where the mixed output signals comprise active matrix decoded signals.

18. A method for processing sound, comprising:

generating decoded signals in response to audio signals; and

generating mixed output signals in response to the decoded signals and the audio signals;

where the mixed output signals comprise active matrix decoded signals when the audio signals comprise a stereo signal; and

where the mixed output signals comprise passive matrix processed signals when the audio signals comprise a monaural signal.

19. The method according to claim 18, further comprising reducing the degree of active matrix decoding in the mixed output signals when the audio signals comprise stereo and monaural signals.

20. The method according to claim 18, where the mixed output signals comprise passive matrix processed signals when the audio signals comprise stereo and monaural signals.

21. The method according to claim 18, where the decoded signals comprise five decoded signals.

22. The method according to claim 18, where the decoded signals comprise seven decoded signals.

23. The method of processing sound according to claim 18, further comprising:

determining band limits of left and right input signals;

calculating a coherence in response to the left and right input signals;

estimating steering angles for a left output signal versus a right output signal and for a center output signal versus a surround output signal; and

limiting the steering angles in response to the coherence.

24. The method of processing sound according to claim 23, where the coherence C is determined by,

25. The method according to claim 18, further comprising:

adding an ambiance signal to the audio signals when the audio signals comprise a monaural signal; and

generating decoded signals in response to the ambiance and audio signals,

where the mixed output signals comprise active matrix decoded signals.

26. The method according to claim 18, further comprising:

forming a synthetic surround signal S_ƒ

calculating a coherence C in response to a left input signal L and a right input signal R;

generating a left virtual stereo signal L_t and a right virtual stereo signal R_t in response to the left and right input signals, the synthetic surround signal, and the coherence; and

generating decoded signals in response to the left and right virtual stereo signals, where the mixed output signals comprise active matrix decoded signals.

27. The method according to claim 26, where

S_f=(L_bl+R_bl)/2 L_t=(X*L)+(Y*S_ƒ

*C) R_t=(X*R)+(Y*S_ƒ

*C)

where L_bl and R_bl are band-limited L and R signals and X and Y are weighting factors.

28. The method according to claim 27, where X=1.707 and Y=0.7.

29. The method according to claim 27, where L_bl and R_bl are band-limited to about 7 KHz.