feat(config): Added ability to listen source rather than sink

[Wohlstand]

Description

Adding the audio_source option that allows to capture explicit source device (like line-in or microphone) rather than capturing an application's sound by making a virtual audio output device to trick the application. In my case I wanted to route the sound source from hardware, and with existing setup it's impossible to do without serious complicated tricks on the audio server by making loopbacks that connects sources and sinks.

By default, audio_source is empty, and behaviour is stay as before. But once audio_source is defined, then Sunshine will explicitly capture audio from the audio source rather than from the sink's monitor.

Screenshot

I don't have any UI changes, only backend.

Issues Fixed or Closed

Discussion: https://github.com/orgs/LizardByte/discussions/830

Roadmap Issues

Nothing

Type of Change

• feat: New feature (non-breaking change which adds functionality)
• fix: Bug fix (non-breaking change which fixes an issue)
• docs: Documentation only changes
• style: Changes that do not affect the meaning of the code (white-space, formatting, missing semicolons, etc.)
• refactor: Code change that neither fixes a bug nor adds a feature
• perf: Code change that improves performance
• test: Adding missing tests or correcting existing tests
• build: Changes that affect the build system or external dependencies
• ci: Changes to CI configuration files and scripts
• chore: Other changes that don't modify src or test files
• revert: Reverts a previous commit
• BREAKING CHANGE: Introduces a breaking change (can be combined with any type above)

Checklist

• Code follows the style guidelines of this project
• Code has been self-reviewed
• Code has been commented, particularly in hard-to-understand areas
• Code docstring/documentation-blocks for new or existing methods/components have been added or updated
• Unit tests have been added or updated for any new or modified functionality

AI Usage

• None: No AI tools were used in creating this PR
• Light: AI provided minor assistance (formatting, simple suggestions)
• Moderate: AI helped with code generation or debugging specific parts
• Heavy: AI generated most or all of the code changes

[Wohlstand]

Okay, now I got another idea how to make this better: maybe implement this as an option of the "Application" entry to capture the hardware source rather than make a fake output device for the work? Otherwise the thing I did will work just globally for all the "applications" if the thing supposed to be used for many people on the same server. In my case I just share stuff from my local PC to my female-friend and we play the same thing.

[codecov]

Bundle Report

Bundle size has no change ✅

[codecov]

❌ 1 Tests Failed:

Tests completed	Failed	Passed	Skipped
230	1	229	8

View the top 1 failed test(s) by shortest run time

ConfigConsistencyTest::AllConfigOptionsExistInAllFiles

Stack Traces | 0.051s run time

D:.../tests/integration/test_config_consistency.cpp:466
Failed
Config options missing from files:
  config.html missing: audio_source
  configuration.md missing: audio_source
  en.json missing: audio_source

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[sonarqubecloud]

Quality Gate passed

Issues
0 New issues
0 Accepted issues

Measures
0 Security Hotspots
0.0% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarQube Cloud

[LizardByte-bot]

It looks like this PR has been idle for 90 days. If it's still something you're working on or would like to pursue, please leave a comment or update your branch. Otherwise, we'll be closing this PR in 10 days to reduce our backlog. Thanks!

[Wohlstand]

I guess I will need to refresh it and make sure it's compatible with the latest state.

[ReenigneArcher]

I guess I will need to refresh it and make sure it's compatible with the latest state.

I don't think anything has changed in regards to audio, so shouldn't be any conflicts.

[Wohlstand]

The another case:

• I didn't documented anything yet.
• Option I made that works on Linux only, I am not sure does it really necessary on Windows and other platforms.
• The option I made, works just globally, but after reviewing how Sunshine is supposed to work, I got a think to try implement it as the "Application-based".

And so, just how I used it actually:

• I combined Sunshine with the modified NXBT thing (NXBT is a daemon that allows to control Nintendo Switch from PC by simulating Pro Controller via raw Bluetooth manipulation).
• I ran Sunshine with "Desktop" only "application" and removed everything.
• I passed to my female-friend who connects Sunshine the screen of Nintendo Switch via full-screen OBS's projector widget and the capture of Line-IN.
• The thing I made allows to don't make me an inconvenience that it steals the default input and this confuses our call done via messenger running on same computer.
• We sometimes might play the game running on same PC, but I making a custom loopback where I manually tell the game to send output into custom sink and I split the sink between loopback and the Sunshine's capturer (based on my line-in thing).

And, generally thing I made I would like to make cleaner and being more stable. I additionally made (but not yet sent) an option that tells Sunshine to don't change audio defaults at all to don't ruin our call conversation.