Audio mixing function

I was wondering if it would be useful to have a function to mix two audio samples with a given ratio. (e.g. Mix two audio with 0.5/0.5 or 0.2/0.8 ratio). Usually as far as I know, mixing audio is adding audio samples and clipping. Or it could be normalized by the number of audio being mixed.

I have been naively mixing audio with ratio, r by : mixed_audio = r * audio_A + (1-r) * audio_B but the result normally doesn’t quite match my expectation as you can easily imagine. So some time ago I came across this paper and code about using A-weighting that takes into consideration the human perception to improve the naive method for real auditory experience, and I am still referring to this paper/code till now.

Mixing function that allows both basic and a-weighted method would be helpful in various situations like data augmentation and creation. Any thoughts on implementing a simple mixing function in librosa? 😃 Thanks!

[justinsalamon]

@kyungyunlee great, glad to hear it, and cheers @lostanlen for the shout out 😃

[lostanlen]

Hi @kyungyunlee!

1. At NYU MARL we are already maintaining a library for musical data augmentation named muda (MUsical Data Augmentation). I you haven’t already done so, please see ISMIR 2015 paper by @bmcfee and Bello: http://bmcfee.github.io/papers/ismir2015_augmentation.pdf It features a BackgroundNoise object-oriented interface for mixing two signals with random weights, one belonging to a pool of “foreground” sounds and the other belonging to a pool of “background” sounds: https://muda.readthedocs.io/en/latest/deformers.html#muda.deformers.BackgroundNoise

2. If you have more than one foreground sound to mix over the background, I would recommend using @justinsalamon’s soundscape generator library scaper: https://github.com/justinsalamon/scaper See his paper from WASPAA 2017

3. From a deterministic standpoint, this can be achieved with a Combiner from @rabitt’s pysox: https://pysox.readthedocs.io/en/latest/api.html#module-sox.combine See her paper from ISMIR-LBD 2016

I personally am a user (and occasional contributor) to each of these three libraries so unless there is a compelling use case for it that is not covered by any of them, I would tend to prefer avoiding porting it to librosa.

Does that make sense?