native-messaging-bash VS captureSystemAudio

I use a Bash start up script every few days when the experiments I run wind up freezing tip-of-tree Chromium or Nightly or the OS itself. The script fetches lastest Firefox Nightly, Chromium Dev Channel installs libtool, libcurl4-openssl-dev, texinfo, cmake, bleachbit, espeak-ng, python3-speechd mpv, git, libssl-dev, clang (or build-essential). I use git frequently. I also wrote a Bash Native Messaging host to communicate from the browser to the local shell script that is W.I.P. https://github.com/guest271314/native-messaging-bash.

Here is a Native Messaging host written in Bash https://github.com/guest271314/native-messaging-bash that you can write stdin to and get stdout from in the browser.

This is how you install and test Native Messaging host, substitute Bash script https://github.com/guest271314/native-messaging-bash and names for for Node.js host https://github.com/guest271314/native-messaging-nodejs.

Bash: https://github.com/guest271314/native-messaging-bash/blob/main/nm_bash.sh

No folders need to be edited. It is not necessary to download a binary. A Native Messaging host using Bash https://github.com/guest271314/native-messaging-bash; I also wrote Native Messaging hosts in C, C++, and QuickJS https://github.com/GoogleChrome/developer.chrome.com/issues/3718#issuecomment-1250341188; others have written Native Messaging hosts in PHP, Python, etc. You should be able to use C# or whatever is the shell on *indows to achieve the same result.

Synchronous. Though non-blocking when we read the message from the browser, execute the command, then stream data output from the local application to the browser piped from QuickJS std.popen(), capture_system_audio.js

I've already achieved the requirement multiple ways, already; from using Native Messaging https://github.com/guest271314/native-messaging-espeak-ng, to using GNU Core Utilities tail, to Deno.watchFs() https://github.com/guest271314/fs, et al., see captureSystemAudio. The one approach I have not yet achieved is compiling to Emscripten - with SSML support.

Sure, see https://github.com/guest271314/captureSystemAudio/blob/master/native_messaging/capture_system_audio/background.js, in pertinent part

This is my second time writing C source code capture_system_audio.c. I got a lot of help doing that, too . I basically implemented the same Native Messaging host algorithm in C, C++, Python, WASI/WebAssembly, and JavaScript (Node.js, QuickJS) which is the programming language I write code most using.

I just fetch the nightly node executable, get rid of everything else in the archive, use .mjs extension for import to work without package.json, then I can connect to the host https://github.com/guest271314/native-messaging-nodejs, and start subprocesses, e.g., raw PCM streams, where stdout is streamed to the client (browser), e.g, https://github.com/guest271314/captureSystemAudio/blob/master/native_messaging/capture_system_audio/capture_system_audio_node.js.

Technically I can just serve the raw data as long as the server is capable of opening creating sub-processes, e.g., using EventSource https://plnkr.co/edit/qX5tepJ38BuDOSZj?preview, in which case I would just need to convert this https://github.com/guest271314/captureSystemAudio/blob/master/native_messaging/capture_system_audio/capture_system_audio.c to accept GET request, read the URL, and send the named event stream to the client.

Chromium and Chrome refuses to capture monitor devices on Linux. Read this https://github.com/edisionnano/Screenshare-with-audio-on-Discord-with-Linux README and the README at https://github.com/guest271314/captureSystemAudio very carefully. At best you can capture tab audio, not whatever is output to speakears and headphones, in spite of the systemAudio constraints, which is poorly named, and actually misleading.

How is capturing speechSynthesis.speak() a security vector https://github.com/guest271314/captureSystemAudio?

Capture audio output to speakers or headphones to MP3 or Opus in WebM https://github.com/guest271314/captureSystemAudio/tree/master/native_messaging/capture_system_audio

An example of using Native Messaging to capture "What-U-Hear", sound output to speakers and headphone, launching native GUI's https://github.com/guest271314/captureSystemAudio/tree/master/native_messaging/capture_system_audio; an adapter for espeak-ng so we can capture the output of speech synthesis engine and stream output to the browser https://github.com/guest271314/native-messaging-espeak-ng.