Methods and systems for mixing digital audio signals

• US 6,882,891 B2
• Filed: 12/06/2000
• Issued: 04/19/2005
• Est. Priority Date: 12/06/2000
• Status: Active Grant

• Current Assignee: Microsoft Technology Licensing LLC (Microsoft Corporation)
• Original Assignee: Microsoft Corporation
• Inventors: Rudolph, Eric H.
• Primary Examiner(s): WOO, STELLA L
• Application Number:
  US09/732,372
• Publication Number:
  US 20020099458A1
• Time in Patent Office: 1,595 Days
• Field of Search: 700/94, 381/119, 381/20, 369/4, 386/52, 386/53, 386/54, 386/93, 386/96, 386/98, 386/99, 386/102, 386/104
• US Class Current: 700/94
• CPC Class Codes: H04H 60/04 Studio equipment; Interconnection of studios

Abstract

Methods and systems for mixing digital audio signals are described. In one embodiment, a result buffer is configured to hold resultant mixed digital audio signals that represent multiple combined input signals. A volume ramp function is calculated based, at least in part, on one or more previously-processed result buffers. A current digital audio signal is processed using the volume ramp function to provide a processed audio signal. In one embodiment, the volume ramp function is a linearly varying function and the current digital audio signal is divided by the volume ramp function. At least portions of the processed audio signal are then written into the result buffer. The process constitutes a one-pass method for autogain control for mixing audio signals.

Claims

1. A method of mixing digital audio signals comprising:

processing multiple result buffers by receiving multiple digital audio signals, providing portions of each of the digital audio signals into individual multi-bit input buffers, and combining the contents of the input buffers in a result buffer to provide a mixed audio signal;

calculating a volume ramp function for a current result buffer as a function of one or more volumes associated with multiple previously-processed result buffers;

combining multiple digital audio signals;

processing the combined digital audio signals with the volume ramp function to provide a processed result signal; and

providing at least some bits from the processed result signal into a result buffer to provide a mixed audio signal.

2. The method of claim 1, wherein said calculating comprises calculating the volume ramp function as a function of one or more maximum volumes associated with the previously-processed result buffers.

3. The method of claim 1, wherein said calculating comprises calculating the volume ramp function as a linearly varying function.

4. The method of claim 1, wherein said calculating comprises calculating a linearly varying volume ramp function as a function of one or more maximum volumes associated with the previously-processed result buffers.

5. The method of claim 1, wherein said calculating comprises calculating the volume ramp function to have start and stop values each of which being calculated based upon different groups of previously-processed result buffers.

6. The method of claim 5, wherein said different groups can have overlapping result buffers.

7. The method of claim 5, wherein said processing of the combined digital audio signals comprises dividing the combined digital audio signal by the volume ramp function.

8. The method of claim 7, wherein the volume ramp function varies linearly between the start and stop values.

9. The method of claim 1, wherein said providing at least some bits comprises selecting a predetermined number of bits from the processed result signal.

10. The method of claim 1, wherein said providing at least some bits comprises selecting predetermined bits from the processed result signal.

11. One or more computer-readable media having computer-readable instructions thereon which, when executed by a computer, implement the method of claim 1.

12. A system comprising:

one or more computer-readable media;

code means embodied on the one or more computer-readable media arid configured to;

process multiple result buffers by receiving multiple digital audio signals, providing portions of each of the digital audio signals into individual multi-bit input buffers, and combining the contents of the input buffers in a result buffer to provide a mixed audio signal;

calculate a volume ramp function for a current result buffer as a function of one or more volumes associated with multiple previously-processed result buffers;

combine multiple digital audio signals;

process the combined digital audio signals with the volume ramp function to provide a processed result signal;

arid

provide at least some bits from the processed result signal into a result buffer to provide a mixed audio signal.

13. The system of claim 12, wherein said code means calculates the volume ramp function as a function of one or more maximum volumes associated with the previously-processed result buffers.

14. The system of claim 12, wherein said code means calculates the volume ramp function as a linearly varying function.

15. The system of claim 12, wherein said code means calculates a linearly varying volume ramp function as a function of one or more maximum volumes associated with the previously-processed result buffers.

16. The system of claim 12, wherein said code means calculates the volume ramp function to have start and stop values each of which being calculated based upon different groups of previously-processed result buffers.

17. The system of claim 16, wherein said different groups can have overlapping result buffers.

18. The system of claim 16, wherein said code means processes the combined digital audio signals by dividing the combined digital audio signal by the volume ramp function.

19. The system of claim 18, wherein the volume ramp function varies linearly between the start and stop values.

20. The system of claim 12, wherein said code means provides at least some bits by selecting a predetermined number of bits from the processed result signal.

21. The system of claim 12, wherein said code means provides at least some bits comprises selecting predetermined bits from the processed result signal.