audio: improve device change on Android

Author: miki

bruig/flutterui/bruig/lib/models/audio.dart

@@ -192,6 +192,8 @@ class AudioModel extends ChangeNotifier {
       }
       androidFoundPlaybackDevices =
           androidEarpieceDeviceID != "" && androidSpeakerDeviceID != "";
+      debugPrint(
+          "FoundPlaybackDevices $androidFoundPlaybackDevices earpiece $androidEarpieceDeviceID speaker $androidSpeakerDeviceID");
     }
 
     notifyListeners();

internal/audio/audio.go

@@ -85,6 +85,7 @@ type audioContext interface {
 // playbackDevice lists the calls needed for a playback device (malgo or sim).
 type playbackDevice interface {
 	Start() error
+	Stop() error
 	Uninit()
 }
 

internal/audio/malgoaudio.go

@@ -176,6 +176,8 @@ func (mpc *malgoContext) initPlayback(deviceID DeviceID, cb dataProc) (playbackD
 	deviceConfig.AAudio.ContentType = malgo.AAudioContentTypeSpeech
 	deviceConfig.AAudio.InputPreset = malgo.AAudioInputPresetVoiceCommunication
 	deviceConfig.AAudio.AllowedCapturePolicy = malgo.AAudioAllowCapturePolicyBySystem
+	deviceConfig.AAudio.NoAutoStartAfterReroute = 1
+	deviceConfig.AAudio.EnableCompatibilityWorkarounds = 0
 
 	playbackCallbacks := malgo.DeviceCallbacks{
 		Data: malgo.DataProc(cb),

internal/audio/streams.go

@@ -5,6 +5,7 @@ import (
 	"errors"
 	"fmt"
 	"math"
+	"runtime"
 	"sync"
 	"time"
 
@@ -858,6 +859,10 @@ func (ps *PlaybackStream) playbackLoopWithDevice(ctx context.Context, devID Devi
 		time.Sleep(time.Millisecond * periodSizeMS)
 	}
 
+	if err := device.Stop(); err != nil {
+		ps.log.Errorf("Playback device %q stop() call errored: %v", devID, err)
+	}
+
 	device.Uninit()
 
 	if addDebugTrace {
@@ -905,6 +910,18 @@ func (ps *PlaybackStream) playbackLoop(ctx context.Context) error {
 				}
 			case <-ctx.Done():
 			}
+
+			if runtime.GOOS == "android" {
+				// Without this extra delay on android, AAudio
+				// sometimes reuses the old device, causes
+				// a re-route in the audio playback stack and
+				// ends up locking up the playback loop.
+				select {
+				case <-time.After(time.Millisecond * 500):
+					ps.log.Debugf("Delayed changed to new device ID %q", devID)
+				case <-ctx.Done():
+				}
+			}
 		}
 	}
 	return ctx.Err()