Sox mixing with a delay

Question

I have a problem with mixing sounds with delay.

I run this

sox -M f1.wav f1.wav f1.wav f1.wav out.wav delay 3 3 4 4 5 5

In the final file volume of the sound is changing(decreasing). How can i avoid this.

Answer 1

You can also control the volume for each of the signals using -v. You hadn't asked for this, but my experience is that at some point you might use this. And it took me a while to find this option online.

sox -m -v 1 file1.wav -v 0.5 file2.wav out.wav

Hope someone finds this useful.

Answer 2

While man sox does not describe automatic attenuation for merge (-M), this surprises me. The following applies to "mix" mode (-m)

Unlike the other methods, 'mix' combining has the potential to cause clipping in the combiner if no balancing is performed. So here, if manual volume adjustments are not given, to ensure that clipping does not occur, SoX will automatically adjust the volume (amplitude) of each input signal by a factor of ¹/ n , where n is the number of input files. If this results in audio that is too quiet or otherwise unbalanced then the input file volumes can be set manually as described above; using the norm effect on the mix is another alternative.

So even though the manual explicitly excludes all modes other than "mix", I would certainly try the 'norm' effect or otherwise specify volume adjustments, since I cannot see how one would merge signals whilst avoiding clipping without attenuating somewhere.