InputMixer decreases volume with multiple streams

[fwillemsen]

I noticed that when mixing 2 or more channels there is a noticable decrease in volume. After modifying the next function I have correct mixing without a change in volume, exactly what I expected and needed.
Possibly I am doing something wrong. I use the default weights of 100. The first stream is fine, adding a second one decreases the volume. Adding a third or more channel keeps the volume stable at the level of the first 2 mixed.

The code that works for me in the InputMixer and that keeps all volumes as it should (for me):

void resultAdd(float fact) {
for (int j = 0; j < current_vect.size(); j++) {

// Enabling the line below causes a decrease in volume. Volume is restored after 1 stream ends.
// current_vect[j] *= fact;
result_vect[j] += current_vect[j];
}
}

Is it possible to tell me if I misunderstood the default configuration and that I need to use other weights or other settings?

The issue resembles #763 but it is slightly different.

Thanks in advance!

[pschatzmann]

Int16 samples are in the range of negative 32768 through positive 32767.
Mixing is just summing up the samples: if you are mixing 3 channels you need to divide each input by 3 to provent an numeric overflow or clipping and loosing info.

[fwillemsen]

Thanks. The problem with this is that mixing a sound with another will decrease the volume level, really an unnatural effect. Just adding the streams works fine for me with the risk of overflow and clipping (not happened so far, testing with 3 mixed streams) and it will prevent the drop in volume This feels a lot more natural.
I guess the behavior of dropping volume is a design decision to prevent overflow and clipping and I will inherit and modify the class for my own purposes as mentioned in the question (leaving out the factor multiplication).
Hopefully I can show a demo of the difference one of those days and post a link to it in the answer.
By the way, a great library! I can mix, adjust volumes, set sample rates, loop and all with a few lines of code!

[fwillemsen]

I received the point where I notice the clipping. So, for me this answers my own question. The original implementation works fine and guarantees good quality at the cost of some shift in volume. My solution is a hack but carefully used it solves my problem for now. So in general best stick to the original code of the audio tools.