Merge changes from topic "startAudioSource_issues" am: 45da2609b7

Original change: https://android-review.googlesource.com/c/platform/frameworks/base/+/1678048

Change-Id: I1c13ec912645eb807c60370408d4c3f28bae1531

media/java/android/media/HwAudioSource.java

@@ -35,7 +35,13 @@ public class HwAudioSource extends PlayerBase {
     private final AudioDeviceInfo mAudioDeviceInfo;
     private final AudioAttributes mAudioAttributes;
 
-    private int mNativeHandle;
+    /**
+     * The value of the native handle encodes the HwAudioSource state.
+     * The native handle returned by {@link AudioSystem#startAudioSource} is either valid
+     * (aka > 0, so successfully started) or hosting an error code (negative).
+     * 0 corresponds to an untialized or stopped HwAudioSource.
+     */
+    private int mNativeHandle = 0;
 
     /**
      * Class constructor for a hardware audio source based player.
@@ -127,29 +133,38 @@ public class HwAudioSource extends PlayerBase {
 
     /**
      * Starts the playback from {@link AudioDeviceInfo}.
+     * Starts does not return any error code, caller must check {@link HwAudioSource#isPlaying} to
+     * ensure the state of the HwAudioSource encoded in {@link mNativeHandle}.
      */
     public void start() {
         Preconditions.checkState(!isPlaying(), "HwAudioSource is currently playing");
-        baseStart();
         mNativeHandle = AudioSystem.startAudioSource(
                 mAudioDeviceInfo.getPort().activeConfig(),
                 mAudioAttributes);
+        if (isPlaying()) {
+            baseStart();
+        }
     }
 
     /**
      * Checks whether the HwAudioSource player is playing.
+     * It checks the state of the HwAudioSource encoded in {@link HwAudioSource#isPlaying}.
+     * 0 corresponds to a stopped or uninitialized HwAudioSource.
+     * Negative value corresponds to a status reported by {@link AudioSystem#startAudioSource} to
+     * indicate a failure when trying to start the HwAudioSource.
+     *
      * @return true if currently playing, false otherwise
      */
     public boolean isPlaying() {
-        return mNativeHandle != 0;
+        return mNativeHandle > 0;
     }
 
     /**
      * Stops the playback from {@link AudioDeviceInfo}.
      */
     public void stop() {
-        baseStop();
         if (mNativeHandle > 0) {
+            baseStop();
             AudioSystem.stopAudioSource(mNativeHandle);
             mNativeHandle = 0;
         }