merge - How does one programmatically mix multiple audio tracks into one track?

Question

What is the algorithm used by Audacity (or any other audio editing program) to mix separate sound tracks?

ie. what is the process of merging the tracks to a single one when the "Mix and Render" command is used.

Answer 1

你只需添加信号。

// fill the destination (output) with the sum of signals: input1, input2, input3
for (size_t idx(0); idx < samplesToWrite; ++idx) {
    output[idx] = input1[idx] + input2[idx] + input3[idx];
}

要将音量或平移应用于信号，请使用乘法。

// to halve the amplitude of an audio signal:
const double halfVolume = 0.5;
for (size_t idx(0); idx < samplesToWrite; ++idx) {
    signal[idx] *= halfVolume;
}