fix(static): raw stereo loopback capture — no voice-call DSP (tin-can fix)

[OmikronApex]

Problem

After the loopback-permission fix (feedBack-desktop #100), song-preview audio reached ASIO and the streamer WASAPI output — but sounded like a tin can. Chromium applies voice-call processing (echo cancellation, noise suppression, AGC, mono downmix) to getDisplayMedia audio tracks by default.

Fix

_engageLoopback now requests echoCancellation:false, noiseSuppression:false, autoGainControl:false, channelCount:2, sampleRate:48000. All best-effort (ideal-valued): unsupported constraints degrade silently rather than failing the capture. The [asio-diag] loopback: line now dumps the track's effective getSettings() so tester logs prove which processing applied.

Verification

Packaged portable build (fix16), ASIO4ALL:

[asio-diag] loopback: suppressed= true pageMuted= false rate= 48000 track= {"sampleRate":48000,"channelCount":2,"echoCancellation":false,"noiseSuppression":false,"autoGainControl":false}
[renderer-bus] engaged: app loopback → engine bus

Tester confirms clean preview audio on ASIO + streamer output.

Companion desktop PR: got-feedBack/feedBack-desktop#100.

🤖 Generated with Claude Code

Summary by CodeRabbit

• Bug Fixes
  • Improved desktop audio loopback capture for cleaner stereo music recording.
  • Audio capture now requests reduced processing, including disabled echo cancellation, noise suppression, and automatic gain control.
  • Added best-effort support for two-channel, 48 kHz audio capture.
• Diagnostics
  • Expanded optional audio diagnostics with detailed capture settings, including sample rate, channel count, and processing flags.

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📝 Walkthrough

Walkthrough

Desktop renderer loopback capture now requests raw stereo audio at 48 kHz with audio processing disabled, while ASIO diagnostics log the resulting track settings as structured JSON.

Changes

Renderer audio capture

Layer / File(s)	Summary
Loopback constraints and diagnostics static/js/juce-audio.js	_engageLoopback requests two-channel, 48 kHz audio with echo cancellation, noise suppression, and automatic gain control disabled; ASIO diagnostics log the track settings as JSON.

Estimated code review effort: 2 (Simple) | ~10 minutes

Possibly related PRs

• got-feedBack/feedBack#852: Extends the same asio-diag renderer-bus diagnostics path.
• got-feedBack/feedBack#865: Introduces the related loopback capture and diagnostics behavior.
• got-feedBack/feedBack#877: Modifies the same whole-application loopback capture pipeline.

🚥 Pre-merge checks | ✅ 5

✅ Passed checks (5 passed)

Check name	Status	Explanation
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Title check	✅ Passed	The title clearly matches the main change: raw stereo loopback capture with DSP disabled.
Docstring Coverage	✅ Passed	No functions found in the changed files to evaluate docstring coverage. Skipping docstring coverage check.
Linked Issues check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Out of Scope Changes check	✅ Passed	Check skipped because no linked issues were found for this pull request.

✨ Finishing Touches

🧪 Generate unit tests (beta)

• Create PR with unit tests
• Commit unit tests in branch fix/loopback-raw-audio

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[OmikronApex]

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