AudioStreamPlayer does not emit signal "finished" when using AudioStreamPolyphonic

[cheesymoo]

Godot version

4.0.stable.official

System information

MacOS 10.14.6

Issue description

When using an AudioStreamPlayer with AudioStreamPolyphonic, no "finished" signal is emitted when a stream finishes playing.

A suggestion:
AudioStreamPolyphonic emits its own "finished" signal that includes the stream id.

Steps to reproduce

Example project attached.

var player = get_node("AudioStreamPlayer")
player.connect("finished", handle_finished)
var playback = player.get_stream_playback
playback_play_stream(preload("res://oneshot.wav")

func handle_finished():
     print("finished")`

Minimal reproduction project

AudioPolyphonicStreamTest.zip

[AThousandShips]

This is because it always returns the requested number of frames when calling mix which is the way the server detects that playback is done

Though I'm not sure this stream is supposed to be finished as you can add new streams to it.

[MJacred]

Related:

• AudioStreamPlayer emits finished signal inconsistently. #56156