Audio processing
AssigneeWolfson Microelectronics plc
InventorAnthony J. Magrath
Life of this patent
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Abstract
The present invention relates to audio signal processing such as equalisation and spatial enhancement functions. The present invention provides an audio signal processing circuit arrangement for two audio channels, and which combines spatial enhancement or acoustic mixing (crosstalk) cancelling with graphic equalisation functions. This is achieved with a circuit structure having a reduced filter count compared with known cascaded circuits dedicated to each function. The circuit structure processes the sum and difference signals through separate filters and then recombines them to recover the separate channels (adding and subtracting respectively).
Claims15
A processing circuit for audio signals and comprising:
- inputs for receiving first and second signals respectively;
- a first filter arranged to process the sum of said signals;
- a second filter arranged to process the difference of said signals;
- a first scaling unit coupled to the first input signal to provide a first scaled signal;
- a second scaling unit coupled to the second input signal to provide a second scaled signal;
- a third scaling unit coupled to the output of the first filter to provide a third scaled signal;
- a fourth scaling unit coupled to the output of the second filter to provide a fourth scaled signal;
- an adder arranged to add the first scaled signal, the third scaled signal and the fourth scaled signal in order to provide a processed first output signal;
- and
- a subtractor arranged to subtract the fourth scaled signal from the sum of the third scaled signal and the second scaled signal in order to provide a processed second output signal.
A method of processing audio signals in order to provide acoustic crosstalk cancellation and/or channel equalisation effects, the method comprising:
- receiving first and second signals corresponding to a left channel and a right channel of a stereo digital audio signal;
- filtering the sum of said signals;
- filtering the difference of said signals;
- scaling the filtered sum of the input signals;
- scaling the filtered difference of the input signals;
- scaling the first signal input;
- scaling the second signal input;
- adding the scaled and filtered difference signal, the scaled and filtered sum signal and the scaled first input signal in order to provide a processed first output signal;
- and
- subtracting the scaled and filtered difference signal from the sum of the scaled and filtered sum signal and the scaled second input signal in order to provide a processed second output signal.
Dependencies are inferred from the claim text.