Support mute/solo/volume for tracks

[swesterfeld]

This is my first attempt to implement mute/solo/volume support for tracks.

What is good:

• user can use volume slider, which has a good non-linear mapping to the track volume
• user can toggle mute/solo to mute and solo tracks

What is incomplete:

• the UI code doesn't pull the initial values from the track
• the UI code doesn't display the new volume dB value if the volume is changed (could be a tooltip)
• I wasn't able to do the slider properly, so right now I do some hacky stuff with numberinput.js to be able to display a slider without any number input; this should be conditional
• serialization isn't implemented (also see below)

Other issues:

Right now the mute/solo/volume interface between the UI and core is done by adding methods to the track. However, these values should support automation in the future. So these values really looks like
AudioProcessor parameters. These have a minimum, maximum, default, non-linear mapping between UI values and actual DSP values, the ability to enter a value directly, and these are serialized automatically by the framework. However, as far as I can see Track is not an AudioProcessor, so I cannot make these parameters here.

Btw, panning isn't implemented yet because we don't have a mixer view, it should be added once we have that.

[swesterfeld]

Update: I've now implemented my first lit element for the track volume. The goal was not to be ultra generic here, but learning how to implement it. With this change we now have a volume slider that works. There is some duplicated code between knob.js and the new trackvolume.js for drag / pointer grab support

[swesterfeld]

Update: I've now migrated the PR to use Track properties instead of Track methods for mute / solo / volume. To support automation in the future, the properties that do support automation (mute and volume) are now part of the AudioProcessor and no longer part of the Track, so these can receive messages while playing. Its not sample accurate yet, but this should be fairly easy to add later on.

The solo logic is a bit tricky because to know whether a track is muted or not, the track needs its own mute state, but also the information whether another track is solo, so this has kind of global state. Since we don't need to automate solo, I can compute the solo state is the non-RT code.

Everything works as far as I can see. The trackvolume.js file has duplicated code with knob.js, this should be moved elsewhere. Other than that, let me know if you see something that you'd like to be improved for merging the PR.

[tim-janik]

@greptile

[greptile-apps]

Greptile Overview

Greptile Summary

This PR implements initial mute/solo/volume support for tracks in Anklang, adding essential mixing controls to the DAW. The implementation spans both the backend audio engine and the frontend UI components. On the backend side, it extends the Track class with solo state management and integrates volume/mute/solo parameters into the AudioChain audio processor with proper smoothing to prevent audio clicks. The frontend introduces new UI components (trackbutton.js, trackvolume.js) that provide interactive controls for these mixing parameters and integrates them into the track view.

The architecture uses a property-based system to bridge the UI and backend, with property change notifications enabling reactive updates. The volume control implements cubic scaling for perceptually better volume curves and includes sophisticated drag interaction with pointer lock functionality. Solo functionality correctly handles the interdependency between tracks - when any track is soloed, all non-solo tracks are muted through a global state management system.

While functional, the developer acknowledges this as an interim solution. The current approach adds methods directly to the Track class rather than using the AudioProcessor parameter framework, which would be necessary for future automation support.

Changed Files

Filename	Score	Overview
ase/properties.hh	5/5	Adds property change notifications by emitting notify signals when values are successfully set
ase/track.hh	3/5	Adds solo member variable and related methods, plus property access infrastructure for track controls
ui/b/trackview.js	4/5	Integrates mute/solo/volume UI controls into the track view with flexbox layout
ase/combo.hh	4/5	Adds volume/mute/solo parameter enums and volume smoothing infrastructure to AudioChain
ui/b/trackbutton.js	2/5	New component for mute/solo toggle buttons with async property binding and notification handling
ase/track.cc	4/5	Implements solo method with global state coordination and temporary property serialization
ase/combo.cc	4/5	Adds volume processing with cubic scaling, smooth transitions, and mute/solo audio logic
ui/b/trackvolume.js	2/5	New volume slider component with complex drag handling and property integration

Confidence score: 3/5

• This PR introduces functional mixing controls but has several implementation gaps and potential runtime issues that require careful testing
• Score reflects incomplete UI synchronization, missing error handling in async property operations, potential infinite loops in notification systems, and acknowledged temporary architectural choices
• Pay close attention to ui/b/trackbutton.js and ui/b/trackvolume.js for async property handling, null pointer safety, and notification loop prevention

Sequence Diagram

sequenceDiagram
    participant User
    participant UI as UI Components (trackbutton.js, trackvolume.js)
    participant Track as TrackImpl
    participant AudioChain as AudioChain
    participant AudioProcessor as AudioProcessor
    participant DSP as DSP Engine

    User->>UI: "Click mute/solo button"
    UI->>Track: "access_property('mute'/'solo')"
    Track->>Track: "create_properties()"
    Track->>UI: "Return property object"
    UI->>Track: "prop.set_value(new_value)"
    Track->>Track: "solo(new_solo) or mute property setter"
    Track->>Track: "set_solo_states()"
    Track->>AudioChain: "send_param(SOLO_STATE, state_value)"
    AudioChain->>AudioProcessor: "apply_event(param_event)"
    AudioProcessor->>DSP: "Process audio with volume adjustment"

    User->>UI: "Drag volume slider"
    UI->>Track: "access_property('volume')"
    Track->>AudioChain: "Return volume parameter"
    UI->>AudioChain: "prop.set_normalized(volume_value)"
    AudioChain->>AudioChain: "volume_smooth_.set(new_volume)"
    AudioChain->>DSP: "Apply volume multiplication in render()"

    DSP->>AudioChain: "Process audio frames with volume"
    AudioChain->>Track: "Update telemetry (dbspl levels)"
    Track->>UI: "Telemetry notifications"
    UI->>User: "Update level meters visually"

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_{8 files reviewed, 16 comments}

_{Edit Code Review Agent Settings | Greptile}

[greptile-apps]

style: Including a device-specific header for LinearSmooth creates a dependency on the blepsynth device. Consider moving LinearSmooth to a more general location like ase/ to avoid coupling AudioChain to specific device implementations.

Prompt To Fix With AI

This is a comment left during a code review.
Path: ase/combo.hh
Line: 6:6

Comment:
**style:** Including a device-specific header for LinearSmooth creates a dependency on the blepsynth device. Consider moving LinearSmooth to a more general location like `ase/` to avoid coupling AudioChain to specific device implementations.

How can I resolve this? If you propose a fix, please make it concise.

[greptile-apps]

logic: JSDoc description incorrectly mentions track volume and <b-trackvolume> but this component handles mute/solo buttons

Prompt To Fix With AI

This is a comment left during a code review.
Path: ui/b/trackbutton.js
Line: 9:10

Comment:
**logic:** JSDoc description incorrectly mentions track volume and `<b-trackvolume>` but this component handles mute/solo buttons

How can I resolve this? If you propose a fix, please make it concise.

[greptile-apps]

logic: Property mapping has no default case - if label is neither 'M' nor 'S', property remains undefined causing line 67 to fail

Prompt To Fix With AI

This is a comment left during a code review.
Path: ui/b/trackbutton.js
Line: 62:66

Comment:
**logic:** Property mapping has no default case - if label is neither 'M' nor 'S', property remains undefined causing line 67 to fail

How can I resolve this? If you propose a fix, please make it concise.

[greptile-apps]

logic: Potential infinite loop: property notify triggers update_value() which could cause recursive calls if property changes during get_value

Prompt To Fix With AI

This is a comment left during a code review.
Path: ui/b/trackbutton.js
Line: 69:72

Comment:
**logic:** Potential infinite loop: property notify triggers `update_value()` which could cause recursive calls if property changes during get_value

How can I resolve this? If you propose a fix, please make it concise.

[tim-janik]

@greptile, How can I resolve this? If you propose a fix, please make it concise.

[greptile-apps]

You can prevent the infinite loop by adding a flag to track when an update is already in progress:

Suggested change

	this.prop.on ("notify", args => {
	if (args.detail == property)
	this.update_value();
	});
	this.prop.on ("notify", args => {
	if (args.detail == property && !this.updating)
	this.update_value();
	});

And modify the update_value method to set the flag:

Suggested change

	this.prop.on ("notify", args => {
	if (args.detail == property)
	this.update_value();
	});
	async update_value()
	{
	if (this.updating) return;
	this.updating = true;
	if (!this.prop)
	{
	let property;
	if (this.label == "M")
	property = "mute";
	if (this.label == "S")
	property = "solo";
	let prop = await this.track.access_property (property);
	this.prop = prop;
	this.prop.on ("notify", args => {
	if (args.detail == property && !this.updating)
	this.update_value();
	});
	}
	this.value = await this.prop.get_value();
	this.updating = false;
	}

This prevents recursive calls by ensuring only one update can happen at a time.

[greptile-apps]

style: Util import is unused and can be removed

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This is a comment left during a code review.
Path: ui/b/trackbutton.js
Line: 5:5

Comment:
**style:** Util import is unused and can be removed

How can I resolve this? If you propose a fix, please make it concise.

[greptile-apps]

logic: Recursive call to update_value() in event handler could cause infinite loop if property updates trigger more notifications

Prompt To Fix With AI

This is a comment left during a code review.
Path: ui/b/trackvolume.js
Line: 76:79

Comment:
**logic:** Recursive call to `update_value()` in event handler could cause infinite loop if property updates trigger more notifications

How can I resolve this? If you propose a fix, please make it concise.

[greptile-apps]

logic: Direct access to global Shell object without null check - component will fail if Shell is not initialized

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This is a comment left during a code review.
Path: ui/b/trackvolume.js
Line: 150:150

Comment:
**logic:** Direct access to global `Shell` object without null check - component will fail if Shell is not initialized

How can I resolve this? If you propose a fix, please make it concise.

[greptile-apps]

logic: Global CONFIG object accessed without null/undefined check

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This is a comment left during a code review.
Path: ui/b/trackvolume.js
Line: 230:230

Comment:
**logic:** Global `CONFIG` object accessed without null/undefined check

How can I resolve this? If you propose a fix, please make it concise.

[greptile-apps]

syntax: Typo in comment: 'sping' should be 'spin'

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This is a comment left during a code review.
Path: ui/b/trackvolume.js
Line: 154:154

Comment:
**syntax:** Typo in comment: 'sping' should be 'spin'

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[greptile-apps]

syntax: Typo in comment: 'sping' should be 'spin'

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This is a comment left during a code review.
Path: ui/b/trackvolume.js
Line: 182:182

Comment:
**syntax:** Typo in comment: 'sping' should be 'spin'

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