Method and apparatus for mixing multiple channels of sampled digital audio using a non-linear clipping function
US5581480A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | May 10, 1994 |
| Grant date | Dec 3, 1996 |
| Priority date | — |
| Expiry date | May 10, 2014 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH04R3/00
- WIPO fieldAudio-visual technology
- WIPO sectorElectrical engineering
Abstract
Briefly, a method and apparatus for mixing a plurality of channels of digital audio samples using a non-linear clipping function which has a variable scaling factor is disclosed. The non-linear curving function is capable of being graphically represented by a curve which is sloped at the edges before reaching the maximum values. In a first embodiment, the non-linear clipping function is applied to the samples and values are calculated in real-time. Preferably, inputs to the non-linear clipping function are modified depending upon any significant trends, e.g. increasing or decreasing, in the sums of samples over time. In a second embodiment, to reduce processor overhead, prior to real time application of the non-linear clipping function, the calculations are performed and a lookup table is generated. This lookup table is then used during real time to apply the clipping function to the input data so that the non-linear function is not recalculated whenever multiple channels are mixed. Lookup tables can be used in combination to apply the non-linear clipping function to a number of channels for which there is not a defined a look up table.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.