[Emacspeak] Me vs. Mac Audio -- The Saga So Far...

[Robert Melton <lists@xxxxxxxxxxx>]

TL;DR: This post just basically says what I have learned so far, and where I am at 
in debugging the robotic and distorted audio issues that can occur on MacOS with
heavy use.  No solutions are below, so if you don't use Mac and don't care about
this issue -- skip it. 

----

What is the issue?

With extended heavy and rapid use of Emacs-Plus (27, 28, 29 or 30) or Emacs-Mac
 on modern MacOS (12+) with any modern Emacspeak (I use master, but this has 
been happening for awhile) the Mac audio subsystem will become garbled, robotic 
and distorted.  This does not impact only sounds from Emacspeak but all sounds, 
including Spotify, other apps, everything.  When you exit emacs this completely is
remedied and stuff normalizes.  Yet, this appears to have a trailing impact in some 
way as once it happens it will very quickly happen if you reopen Emacs.


----

What have you looked at as the cause? 

At first, myself and other users expected it might have to do with 3rd party audio
 modifications on MacOS, and while this does make it more pronounced, it is not
 the cause, I have confirmed on a few complete install on an M1 Mac Mini.

The next idea was that it was a specific version of Emacs, specifically Emacs-Mac. 
Again, this was a contributing factor to the problem, but not the cause. I produced 
it with a fresh built Emacs-Plus 28.2.

So, then I thought it might be the python mac server, so I wrote a new one in Go 
to see if this was the case, and while building (and using) my new server, the bug
 came up again. So it isn't the python mac server. I might complete the server, it is 
just really getting started at https://github.com/robertmeta/fastmac -- I still want a 
faster more easily concurrent server for Mac that has less requirements to install. 

So then I thought it might be thrashing the audio API on mac via the sounds 
playback in the mac server (which applies to tones as well, patch incoming soon) 
and while this was an improvement and again might have added to the mean time
between failures -- it was again not the core issue. 

By pure luck, as I was doing this stuff over the last few weeks I started using and
 loving Ivy and Swiper. This was great timing, as I can consistently bug out my 
sound with Ivy and Swiper witha couple tries. It appears to be related to sounds 
played during typing / using backsapce in like swiper for example. With enough 
overlapping / concurrent noises the sound gets blown out.

So with a lot more digging, I confirmed that this is completely unrelated to the 
python mac server!  With audio icons disabled this bug is completely gone, does 
not occur in any way that I can cause. 

---- 

So where are we now? 

I am in the process of understanding how the audio icons work and how they get 
attached to events and where the code that actually interfaces with the MacOS 
audio system lives.  I am new to Emacs and Lisp so I am slower than the average 
bear at finding the right place, but slowly but surely making progress... any tips and 
pointers greatly appreciated. 

----

Anything you specifically didn't try yet? 

I did not try with the base Emacs package that can be installed with brew.  It feels 
very far from working with my config and setup so I have not dove in too far to 
testing it, This is indeed worth testing and I will probably attempt it this weekend. 

-- 
Robert "robertmeta" Melton