Improve multitrack player

[bryan-pardo]

Describe the bug
Take 2 copies of the same audio signal. Hand them to multitrack to produce a 2-track player. Play both tracks simultaneously. There's an echo. Ergo, the tracks are playing a touch out of synch.

Steps To Reproduce

Do this in a python notebook.

import nussl
import matplotlib.pyplot as plt
import numpy as np
from pprint import pprint
from common import viz

signal = nussl.AudioSignal('path/to/file.wav')
signal.stft()
viz.show_sources({'copy A': signal, 'copy B': signal})

Now...run the audio player with both tracks playing.

Expected behavior
You should hear only one signal
What did happen
You hear a signal with an echo.
Audio output
Run it for yourself.

Software versions*
I ran this in Google CoLab

Linux-4.19.112+-x86_64-with-Ubuntu-18.04-bionic
Python 3.6.9 (default, Oct 8 2020, 12:12:24)
[GCC 8.4.0]
NumPy 1.19.4
SciPy 1.4.1
nussl 1.1.3rc5

[Atralb]

Hi there, I'm having an issue with common.viz.show_sources too, but it's another one: only the graphs are printed, not the player (like here). Here is a screenshot showcasing the issue.

I'm having a real trouble finding the origin of this module. I've skimmed through the source code in /opt/conda/lib/python3.8/site-packages/common/viz.py, so I understand it is directly related to nussl, but where does it come from ? I can't seem to find this common module in the repo here.

[pseeth]

Hi @bryan-pardo, yeah the multitrack player can be improved for sure...it's down to using media elements to play the audio instead of using something more robust like Web Audio API. It's a bit low on the priority list right now, but I have an attempt lying around using trackswitch.js. Usually, with the current multitrack player, I can fix it by just stopping and restarting it.

@Atralb, the common library is not a pip library, rather it's just a set of utilities that was helpful for writing the source separation book. Here is the "library": https://github.com/source-separation/tutorial (under the common package). It gets installed when you clone the tutorial and install it via pip install -e .. By the way, it seems like you're using conda but not using conda environments. I recommend using conda environments to avoid any issues.

As for your issue, I've seen that happen sometimes in other browsers. Usually rerunning the code cell works. The multitrack player sometimes goes away when you refresh the page, when running it in a notebook.

I'm going to rename this issue to "Improve multitrack player", self-assign it, and keep track of progress here.

[Atralb]

@pseeth Thanks a lot for the answer ! Of course, I forgot to check in source-separation/tutorial, dummy me...

And you're actually right about the player... rerunning the cell now makes it appear. I had tried rerunning a second time when I first encountered the issue, and since it didn't work then, I directly assumed this was an issue with my installation afterwards. Sorry for having gone too fast :/

As for conda and envs, I'm actually running a jupyter notebook server in an ad hoc docker container with a custom image based on scipy-notebook from jupyter/docker-stacks over which I added nussl, so that's why I don't shouldn't need a virtual env.

PS: By the way, if you'd rather I moved my own message in a specific issue to separate it from bryan-pardo's one, I can :). Whatever you prefer.