Method and apparatus for the distribution and enhancement of digital compressed audio

• US 6,865,430 B1
• Filed: 09/10/1999
• Issued: 03/08/2005
• Est. Priority Date: 09/10/1999
• Status: Expired due to Fees

• Current Assignee: David W. Runton, Peter A. Smith
• Original Assignee: David W. Runton, Peter A. Smith
• Inventors: Smith, Peter A., Runton, David W.
• Primary Examiner(s): Lee, Ping
• Application Number:
  US09/393,525
• Time in Patent Office: 2,006 Days
• Field of Search: 381/119, 381/62, 381/98, 381/118, 381/61, 846/60, 846/25, 700/94
• US Class Current: 700/94
• CPC Class Codes: G10H 1/0091 Means for obtaining special acoustic effects combined with modulation G10H1/043
• CPC Class Codes: G10H 2210/311 Distortion, i.e. desired non-linear audio processing to change the tone color, e.g. by adding harmonics or deliberately distorting the amplitude of an audio waveform distortion functions G10H2250/201, G10H2250/205
• CPC Class Codes: G10H 2240/061 MP3, i.e. MPEG-1 or MPEG-2 Audio Layer III, lossy audio compression
• CPC Class Codes: G10L 19/26 Pre-filtering or post-filtering

Abstract

Disclosed are apparatus and methods of enhancing digital audio signals after compression and decompression. The methods and apparatus include receiving a digital decompressed audio signal, harmonically enhancing the signal, adding warmth to the signal, and combining and frequency equalizing the harmonically enhanced audio signal and the warmth enhanced audio signal to provide a digital enhanced decompressed audio signal. The apparatus is preferably provided in software as instructions to a DSP. Adjustments are included within the software for varying levels of the harmonic enhancing and for varying levels of the frequency equalizing. Methods of distribution are disclosed which include providing the software free with the inclusion in the software of either a one-time use, a partial use, a partially enhanced audio signal use, or non-save adjustments, and selling the software for a price without including the one-time use, the partial use, the partially enhanced audio signal use, or the non-save adjustments.

Claims

1. Apparatus for enhancing digital audio signals after the digital audio signals are compressed and decompressed, the apparatus comprising:

an input terminal for receiving a digital decompressed audio signal;

a digital harmonic enhancer coupled to receive the digital decompressed audio signal and provide a harmonically enhanced audio signal, the harmonic enhancer includes a digital amplifier coupled to provide harmonic distortion, a digital high pass filter coupled to receive the digital decompressed audio signal and to provide a digital high pass audio signal to the digital amplifier, and a digital level adjuster coupled to receive the harmonic distortion from the digital amplifier and to provide a level adjusted harmonic distortion audio signal to one input of a digital adder, the digital adder having a second input coupled to receive the digital decompressed audio signal and to add the harmonically enhanced audio signal to the digital decompressed audio signal to produce the harmonically enhanced audio signal;

a digital warmth adder coupled to receive the digital decompressed audio signal and provide a warmth enhanced audio signal; and

a digital frequency equalizer coupled to receive the harmonically enhanced audio signal and the warmth enhanced audio signal and provide a digital enhanced decompressed audio signal.

2. Apparatus as claimed in claim 1 wherein the digital compressed audio signal and the digital decompressed audio signal includes an MP3 format.

3. Apparatus as claimed in claim 1 wherein the digital high pass filter includes an adjustment for varying a frequency band of the digital high pass audio signal.

4. Apparatus as claimed in claim 1 wherein the digital level adjuster includes an adjustment for varying a level of the harmonic distortion from the digital amplifier.

5. Apparatus as claimed in claim 1 wherein the warmth adder includes a saturated digital amplifier with an S-shaped response curve.

6. Apparatus as claimed in claim 5 wherein the response curve of the saturated digital amplifier includes upper and lower saturation areas which are rounded to provide warmth distortion.

7. Apparatus as claimed in claim 1 wherein the frequency equalizer includes a plurality of adjustments for varying levels of different frequency bands within the harmonically enhanced audio signal and the warmth enhanced audio signal.

8. Apparatus as claimed in claim 1 wherein the digital harmonic enhancer, the digital warmth adder, and the digital frequency equalizer are included in a digital signal processor.

9. Apparatus as claimed in claim 1 wherein the digital harmonic enhancer, the digital warmth adder, and the digital frequency equalizer are provided as software for a digital signal processor.

10. Apparatus as claimed in claim 9 wherein the digital harmonic enhancer and the digital frequency equalizer include adjustments for varying a level of the harmonic distortion and for varying levels of different frequency bands within the harmonically enhanced audio signal and the warmth enhanced audio signal.

11. Apparatus as claimed in claim 10 wherein the adjustments are preset to levels determined by an expert of the received digital decompressed audio signal.

12. Apparatus for enhancing digital audio signals after the digital audio signals are compressed and decompressed, the apparatus comprising:

an input terminal for receiving a digital decompressed audio signal;

a digital harmonic enhancer coupled to receive the digital decompressed audio signal and provide a harmonically enhanced audio signal, the harmonic enhancer including a digital high pass filter coupled to receive the digital decompressed audio signal and to provide a digital high pass audio signal, a digital amplifier coupled to receive the digital high pass audio signal and to provide harmonic distortion of the digital high pass audio signal, and a digital level adjuster coupled to receive the harmonically distorted digital high pass audio signal from the digital amplifier and to provide a level adjusted harmonic distortion audio signal to one input of a digital adder, the digital adder having a second input coupled to receive the digital decompressed audio signal and to add the harmonically distorted digital high pass audio signal to the digital decompressed audio signal to produce the harmonically enhanced audio signal, the digital high pass filter including an adjustment for varying a frequency band of the digital high pass audio signal, and the digital level adjuster including an adjustment for varying a level of the harmonic distortion from the digital amplifier;

a digital warmth adder coupled to receive the digital decompressed audio signal and provide a warmth enhanced audio signal, the digital warmth adder including a saturated digital amplifier with an S-shaped response curve wherein the upper and lower saturation areas are rounded to provide warmth distortion; and

a digital frequency equalizer coupled to receive the harmonically enhanced audio signal and the warmth enhanced audio signal and provide a digital enhanced decompressed audio signal.

13. Apparatus as claimed in claim 12 wherein the digital harmonic enhancer, the digital warmth adder, and the digital frequency equalizer are included in a digital signal processor.

14. Apparatus as claimed in claim 12 wherein the digital harmonic enhancer, the digital warmth adder, and the digital frequency equalizer are provided as software for a digital signal processor.

15. Apparatus as claimed in claim 14 wherein the digital harmonic enhancer and the digital frequency equalizer include adjustments for varying a level of the harmonic distortion and for varying levels of different frequency bands within the harmonically enhanced audio signal and the warmth enhanced audio signal.

16. Apparatus as claimed in claim 15 wherein the adjustments are preset to levels determined by an expert of the received digital decompressed audio signal.

17. A method of enhancing digital audio signals after the digital audio signals are compressed and decompressed, the method comprising the steps of:

receiving a digital decompressed audio signal;

harmonically enhancing the digital decompressed audio signal by digitally high pass filtering the digital decompressed audio signal to provide a digital high pass audio signal, digitally amplifying the digital high pass audio signal to provide harmonic distortion, adjusting a level of the harmonic distortion from the digital amplifier and providing a level adjusted harmonic distortion audio signal to one input of a digital adder, coupling a second input of the digital adder to receive the digital decompressed audio signal, and adding the harmonically enhanced audio signal to the digital decompressed audio signal in the digital adder to produce a harmonically enhanced audio signal;

adding warmth to the digital decompressed audio signal and providing a warmth enhanced audio signal; and

combining and frequency equalizing the harmonically enhanced audio signal and the warmth enhanced audio signal to provide a digital enhanced decompressed audio signal.

18. A method as claimed in claim 17 wherein the step of receiving includes receiving a digital decompressed audio signal produced from a digital compressed audio signal using an MP3 format.

19. A method as claimed in claim 17 wherein the step of harmonically enhancing the digital decompressed audio signal includes providing an adjustment for varying a frequency band of the digital high pass audio signal.

20. A method as claimed in claim 17 wherein the step of adding warmth to the digital decompressed audio signal includes saturation amplifying the digital decompressed audio signal with an S-shaped amplification response curve.

21. A method as claimed in claim 20 wherein the step of saturation amplifying includes producing upper and lower saturation areas which are rounded to provide warmth distortion.

22. A method as claimed in claim 17 wherein the step of combining and frequency equalizing includes providing a plurality of adjustments for varying levels of different frequency bands within the harmonically enhanced audio signal and the warmth enhanced audio signal.

23. A method as claimed in claim 17 including providing the steps of harmonically enhancing, adding warmth, and combining and frequency equalizing in a digital signal processor.

24. A method as claimed in claim 23 wherein the steps of harmonically enhancing and combining and frequency equalizing include providing adjustments for varying a level of the harmonic enhancing and for varying levels of different frequency bands within the harmonically enhanced audio signal and the warmth enhanced audio signal.

25. A method as claimed in claim 24 wherein the step of providing adjustments includes providing preset levels determined by an expert of the received digital decompressed audio signal.

26. A method as claimed in claim 17 including providing the steps of harmonically enhancing, adding warmth, and combining and frequency equalizing as software for a digital signal processor.

27. A method of enhancing digital audio signals after the digital audio signals are compressed and decompressed, the method comprising the steps of:

receiving a digital decompressed audio signal;

harmonically enhancing the digital decompressed audio signal and providing a harmonically enhanced audio signal, the step of harmonically enhancing the digital decompressed audio signal including digitally high pass filtering the digital decompressed audio signal to provide a digital high pass audio signal, digitally amplifying the digital high pass audio signal to provide harmonic distortion, and adjusting a level of the harmonic distortion from the digital amplifier and providing a level adjusted harmonic distortion audio signal to one input of a digital adder, coupling a second input of the digital adder to receive the digital decompressed audio signal, and adding the harmonically enhanced audio signal to the digital decompressed audio signal in the digital adder to produce the harmonically enhanced audio signal;

adding warmth to the digital decompressed audio signal and providing a warmth enhanced audio signal including saturation amplifying the digital decompressed audio signal with an S-shaped amplification response curve producing upper and lower saturation areas which are rounded to provide warmth distortion; and

combining and frequency equalizing the harmonically enhanced audio signal and the warmth enhanced audio signal to provide a digital enhanced decompressed audio signal.

28. A method as claimed in claim 27 including providing the steps of harmonically enhancing, adding warmth, and combining and frequency equalizing in a digital signal processor.

29. A method as claimed in claim 27 wherein the steps of harmonically enhancing and combining and frequency equalizing include providing adjustments for varying a level of the harmonic enhancing and for varying levels of different frequency bands within the harmonically enhanced audio signal and the warmth enhanced audio signal.

30. A method as claimed in claim 29 wherein the step of providing adjustments includes providing preset levels determined by an expert of the received digital decompressed audio signal.

31. A method as claimed in claim 27 including providing the steps of harmonically enhancing, adding warmth, and combining and frequency equalizing as software for a digital signal processor.