Class: StereoMixer

Overview

Mixes up to 4 stereo inputs. From the traditional mixer hardware point of view, every input and the output has dedicated metering, gain and pan controls.

One instance allocates just a few bytes of memory. Combining multiple instances of the StereoMixer is the recommended way to support more than 4 channels.

How to implement

// Constructor. Has no additional parameters.
let mixer = new Superpowered.StereoMixer();

// Gain per input channel, 8 values (2 per input). Default value for all: 1. Changes between consecutive process() calls are automatically smoothed.
mixer.inputGain[2] = 0.5; // left side of the second input
mixer.inputGain[3] = 0.5; // right side of the second input

// Output gain. Default value for all: 1. Changes between consecutive process() calls are automatically smoothed.
mixer.outputGain[0] = 0.9; // left side
mixer.outputGain[1] = 0.8; // right side

// Processes the audio. Has no return value.
mixer.process(
    input0, // Pointer to floating point numbers. 32-bit interleaved stereo input buffer for the first input. Can be null.
    input1, // Pointer to floating point numbers. 32-bit interleaved stereo input buffer for the second input. Can be null.
    input2, // Pointer to floating point numbers. 32-bit interleaved stereo input buffer for the third input. Can be null.
    input3, // Pointer to floating point numbers. 32-bit interleaved stereo input buffer for the fourth input. Can be null.
    output, // Pointer to floating point numbers. 32-bit interleaved stereo output buffer.
    128     // Number of frames to process. Must be an even number.
);

// The peak absolute audio volume per input channel, updated after every process() call, measured before any gain.
let second_input_left_side = mixer.inputPeak[2];
let second_input_right_side = mixer.inputPeak[3];

// The peak absolute audio volume for the output, updated after every process() call.
let output_left_side = mixer.outputPeak[0];
let output_right_side = mixer.outputPeak[1];

// Destructor (to free up memory).
mixer.destruct();

#include "SuperpoweredMixer.h"

void initMixer() {
    mixer = new Superpowered::StereoMixer();

    // Gain per input channel, 8 values (2 per input). Default value for all: 1. Changes between consecutive process() calls are automatically smoothed.
    mixer->inputGain[2] = 0.5;
    mixer->inputGain[3] = 0.5;

    // Output gain. Default value for all: 1. Changes between consecutive process() calls are automatically smoothed.
    mixer->outputGain[0] = 0.9; // left side
    mixer->outputGain[1] = 0.8; // right side
}

void processAudio(float *interleavedInput, float *interleavedOutput, unsigned int numberOfFrames) {
    mixer->process(input0, input1, input2, input3, interleavedOutput, numberOfFrames);

    // The peak absolute audio volume per input channel, updated after every process() call, measured before any gain.
    float second_input_left_side = mixer->inputPeak[2];
    float second_input_right_side = mixer->inputPeak[3];

    // The peak absolute audio volume for the output, updated after every process() call.
    float output_left_side = mixer->outputPeak[0];
    float output_right_side = mixer->outputPeak[1];
}

Properties

Array[8]

float[8]

Array[8]

float[8]

Array[2]

float[2]

Array[2]

float[2]

Methods

• constructor

  METHOD

  Creates a StereoMixer instance.

  Parameters

  None

  Returns

  Type	Description
  Superpowered.StereoMixer	The constructed instance.

• constructor

  METHOD

  Creates a StereoMixer instance.

  Parameters

  None

  Returns

  Type	Description
  Superpowered::StereoMixer	The constructed instance.

• destruct

  METHOD

  Destructor to free Linear Memory.

  Parameters

  None

  Returns

  None

• process

  METHOD

  Mixes up to 4 mono inputs into a stereo output.

  Parameters

  Name	Type	Description
  input0	Number (pointer in Linear Memory)	32-bit input buffer for the first stereo input. Can be 0.
  input1	Number (pointer in Linear Memory)	32-bit input buffer for the second stereo input. Can be 0.
  input2	Number (pointer in Linear Memory)	32-bit input buffer for the third stereo input. Can be 0.
  input3	Number (pointer in Linear Memory)	32-bit input buffer for the fourth stereo input. Can be 0.
  output	Number (pointer in Linear Memory)	32-bit output buffer.
  numberOfFrames	Number	Number of frames to process. Must be a multiple of 4.

  Returns

  None

• process

  METHOD

  Mixes up to 4 mono inputs into a stereo output.

  Parameters

  Name	Type	Default	Description
  input0	float *		32-bit input buffer for the first stereo input. Can be NULL.
  input1	float *		32-bit input buffer for the second stereo input. Can be NULL.
  input2	float *		32-bit input buffer for the third stereo input. Can be NULL.
  input3	float *		32-bit input buffer for the fourth stereo input. Can be NULL.
  output	float *		32-bit output buffer.
  numberOfFrames	unsigned int		Number of frames to process. Must be a multiple of 4.

  Returns

  None