Support adding and removing MediaRecorder to camera 2 session.

webrtc/sdk/android/src/java/org/webrtc/CameraCapturer.java

 /*
  *  Copyright 2016 The WebRTC project authors. All Rights Reserved.
  *
  *  Use of this source code is governed by a BSD-style license
  *  that can be found in the LICENSE file in the root of the source
  *  tree. An additional intellectual property rights grant can be found
  *  in the file PATENTS.  All contributing project authors may
  *  be found in the AUTHORS file in the root of the source tree.
  */
 
 package org.webrtc;
 
 import android.content.Context;
+import android.media.MediaRecorder;
 import android.os.Handler;
 import android.os.Looper;
 import java.util.Arrays;
 
 @SuppressWarnings("deprecation")
 abstract class CameraCapturer implements CameraVideoCapturer {
   enum SwitchState {
     IDLE, // No switch requested.
     PENDING, // Waiting for previous capture session to open.
     IN_PROGRESS, // Waiting for new switched capture session to start.
   }
 
+  enum MediaRecorderState {
+    IDLE, // No media recording update (add or remove) requested.
+    IDLE_TO_ACTIVE, // Waiting for new capture session with added MediaRecorder surface to start.
+    ACTIVE_TO_IDLE, // Waiting for new capture session with removed MediaRecorder surface to start.
+    ACTIVE, // MediaRecorder was successfully added to camera pipeline.
+  }
+
   private static final String TAG = "CameraCapturer";
   private final static int MAX_OPEN_CAMERA_ATTEMPTS = 3;
   private final static int OPEN_CAMERA_DELAY_MS = 500;
   private final static int OPEN_CAMERA_TIMEOUT = 10000;
 
   private final CameraEnumerator cameraEnumerator;
   private final CameraEventsHandler eventsHandler;
   private final Handler uiThreadHandler;
 
   private final CameraSession.CreateSessionCallback createSessionCallback =
       new CameraSession.CreateSessionCallback() {
         @Override
         public void onDone(CameraSession session) {
           checkIsOnCameraThread();
-          Logging.d(TAG, "Create session done");
+          Logging.d(TAG,
+              "Create session done. Switch state: " + switchState
+                  + ". MediaRecorder state: " + mediaRecorderState);
           uiThreadHandler.removeCallbacks(openCameraTimeoutRunnable);
           synchronized (stateLock) {
             capturerObserver.onCapturerStarted(true /* success */);
             sessionOpening = false;
             currentSession = session;
             cameraStatistics = new CameraStatistics(surfaceHelper, eventsHandler);
             firstFrameObserved = false;
             stateLock.notifyAll();
 
             if (switchState == SwitchState.IN_PROGRESS) {
               if (switchEventsHandler != null) {
                 switchEventsHandler.onCameraSwitchDone(cameraEnumerator.isFrontFacing(cameraName));
                 switchEventsHandler = null;
               }
               switchState = SwitchState.IDLE;
             } else if (switchState == SwitchState.PENDING) {
               switchState = SwitchState.IDLE;
               switchCameraInternal(switchEventsHandler);
             }
+
+            if (mediaRecorderState == MediaRecorderState.IDLE_TO_ACTIVE
+                || mediaRecorderState == MediaRecorderState.ACTIVE_TO_IDLE) {
+              if (mediaRecorderEventsHandler != null) {
+                mediaRecorderEventsHandler.onMediaRecorderSuccess();
+                mediaRecorderEventsHandler = null;
+              }
+              if (mediaRecorderState == MediaRecorderState.IDLE_TO_ACTIVE) {
+                mediaRecorderState = MediaRecorderState.ACTIVE;
+              } else {
+                mediaRecorderState = MediaRecorderState.IDLE;
+              }
+              mediaRecorder = null;
+            }
           }
         }
 
         @Override
         public void onFailure(CameraSession.FailureType failureType, String error) {
           checkIsOnCameraThread();
           uiThreadHandler.removeCallbacks(openCameraTimeoutRunnable);
           synchronized (stateLock) {
             capturerObserver.onCapturerStarted(false /* success */);
             openAttemptsRemaining--;
 
             if (openAttemptsRemaining <= 0) {
               Logging.w(TAG, "Opening camera failed, passing: " + error);
               sessionOpening = false;
               stateLock.notifyAll();
 
               if (switchState != SwitchState.IDLE) {
                 if (switchEventsHandler != null) {
                   switchEventsHandler.onCameraSwitchError(error);
                   switchEventsHandler = null;
                 }
                 switchState = SwitchState.IDLE;
               }
 
+              if (mediaRecorderState != MediaRecorderState.IDLE) {
+                if (mediaRecorderEventsHandler != null) {
+                  mediaRecorderEventsHandler.onMediaRecorderError(error);
+                  mediaRecorderEventsHandler = null;
+                }
+                mediaRecorderState = MediaRecorderState.IDLE;
+                mediaRecorder = null;
+              }
+
               if (failureType == CameraSession.FailureType.DISCONNECTED) {
                 eventsHandler.onCameraDisconnected();
               } else {
                 eventsHandler.onCameraError(error);
               }
             } else {
               Logging.w(TAG, "Opening camera failed, retry: " + error);
 
               createSessionInternal(OPEN_CAMERA_DELAY_MS);
             }
@@ skipping 97 matching lines @@
       eventsHandler.onCameraError("Camera failed to start within timeout.");
     }
   };
 
   // Initialized on initialize
   // -------------------------
   private Handler cameraThreadHandler;
   private Context applicationContext;
   private CapturerObserver capturerObserver;
   private SurfaceTextureHelper surfaceHelper;
+  private MediaRecorder mediaRecorder;

[sakal, 2017/04/24 09:17:32]

I don't think this member variable is needed. It can just be an argument to
createSessionInternal. The less state we have the better.

At least it is not initialized on initialize so it doesn't belong here.

[AlexG, 2017/04/25 23:11:51]

This is actually used during re attempting to open camera session - in
createSessionCallback.onFailure. We need to cache the value to use during these
attempts - similar to say cameraName. I moved the declaration to a better place

[sakal, 2017/04/26 07:34:11]

But you set openAttemptsRemaining = 1; in updateMediaRecorderInternal so there
will be no retries?

 
   private final Object stateLock = new Object();
   private boolean sessionOpening; /* guarded by stateLock */
   private CameraSession currentSession; /* guarded by stateLock */
   private String cameraName; /* guarded by stateLock */
   private int width; /* guarded by stateLock */
   private int height; /* guarded by stateLock */
   private int framerate; /* guarded by stateLock */
   private int openAttemptsRemaining; /* guarded by stateLock */
   private SwitchState switchState = SwitchState.IDLE; /* guarded by stateLock */
   private CameraSwitchHandler switchEventsHandler; /* guarded by stateLock */
   // Valid from onDone call until stopCapture, otherwise null.
   private CameraStatistics cameraStatistics; /* guarded by stateLock */
   private boolean firstFrameObserved; /* guarded by stateLock */
 
+  // Variables used on camera thread - do not require stateLock synchronization.
+  private MediaRecorderState mediaRecorderState = MediaRecorderState.IDLE;
+  private MediaRecorderHandler mediaRecorderEventsHandler;
+
   public CameraCapturer(
       String cameraName, CameraEventsHandler eventsHandler, CameraEnumerator cameraEnumerator) {
     if (eventsHandler == null) {
       eventsHandler = new CameraEventsHandler() {
         @Override
         public void onCameraError(String errorDescription) {}
         @Override
         public void onCameraDisconnected() {}
         @Override
         public void onCameraFreezed(String errorDescription) {}
@@ skipping 54 matching lines @@
       createSessionInternal(0);
     }
   }
 
   private void createSessionInternal(int delayMs) {
     uiThreadHandler.postDelayed(openCameraTimeoutRunnable, delayMs + OPEN_CAMERA_TIMEOUT);
     cameraThreadHandler.postDelayed(new Runnable() {
       @Override
       public void run() {
         createCameraSession(createSessionCallback, cameraSessionEventsHandler, applicationContext,
-            surfaceHelper, cameraName, width, height, framerate);
+            surfaceHelper, mediaRecorder, cameraName, width, height, framerate);
       }
     }, delayMs);
   }
 
   @Override
   public void stopCapture() {
     Logging.d(TAG, "Stop capture");
 
     synchronized (stateLock) {
       while (sessionOpening) {
@@ skipping 42 matching lines @@
     Logging.d(TAG, "switchCamera");
     cameraThreadHandler.post(new Runnable() {
       @Override
       public void run() {
         switchCameraInternal(switchEventsHandler);
       }
     });
   }
 
   @Override
+  public void addMediaRecorderToCamera(
+      final MediaRecorder mediaRecorder, final MediaRecorderHandler mediaRecoderEventsHandler) {
+    Logging.d(TAG, "addMediaRecorderToCamera");
+    cameraThreadHandler.post(new Runnable() {
+      @Override
+      public void run() {
+        updateMediaRecorderInternal(
+            true /* addMediaRecorder */, mediaRecorder, mediaRecoderEventsHandler);
+      }
+    });
+  }
+
+  @Override
+  public void removeMediaRecorderFromCamera(final MediaRecorderHandler mediaRecoderEventsHandler) {
+    Logging.d(TAG, "removeMediaRecorderFromCamera");
+    cameraThreadHandler.post(new Runnable() {
+      @Override
+      public void run() {
+        updateMediaRecorderInternal(
+            false /* addMediaRecorder */, null /* mediaRecorder */, mediaRecoderEventsHandler);
+      }
+    });
+  }
+
+  @Override
   public boolean isScreencast() {
     return false;
   }
 
   public void printStackTrace() {
     Thread cameraThread = null;
     if (cameraThreadHandler != null) {
       cameraThread = cameraThreadHandler.getLooper().getThread();
     }
     if (cameraThread != null) {
       StackTraceElement[] cameraStackTrace = cameraThread.getStackTrace();
       if (cameraStackTrace.length > 0) {
         Logging.d(TAG, "CameraCapturer stack trace:");
         for (StackTraceElement traceElem : cameraStackTrace) {
           Logging.d(TAG, traceElem.toString());
         }
       }
     }
   }
 
+  private void reportCameraSwitchError(String error, CameraSwitchHandler switchEventsHandler) {
+    Logging.e(TAG, error);
+    if (switchEventsHandler != null) {
+      switchEventsHandler.onCameraSwitchError(error);
+    }
+  }
+
   private void switchCameraInternal(final CameraSwitchHandler switchEventsHandler) {
     Logging.d(TAG, "switchCamera internal");
 
     final String[] deviceNames = cameraEnumerator.getDeviceNames();
 
     if (deviceNames.length < 2) {
       if (switchEventsHandler != null) {
         switchEventsHandler.onCameraSwitchError("No camera to switch to.");
       }
       return;
     }
 
     synchronized (stateLock) {
       if (switchState != SwitchState.IDLE) {
-        Logging.d(TAG, "switchCamera switchInProgress");
-        if (switchEventsHandler != null) {
-          switchEventsHandler.onCameraSwitchError("Camera switch already in progress.");
-        }
+        reportCameraSwitchError("Camera switch already in progress.", switchEventsHandler);
+        return;
+      }
+      if (mediaRecorderState != MediaRecorderState.IDLE) {
+        reportCameraSwitchError("switchCamera: media recording is active", switchEventsHandler);
+        return;
+      }
+      if (!sessionOpening && currentSession == null) {
+        reportCameraSwitchError("switchCamera: camera is not running.", switchEventsHandler);
         return;
       }
 
-      if (!sessionOpening && currentSession == null) {
-        Logging.d(TAG, "switchCamera: No session open");
-        if (switchEventsHandler != null) {
-          switchEventsHandler.onCameraSwitchError("Camera is not running.");
-        }
-        return;
-      }
-
       this.switchEventsHandler = switchEventsHandler;
       if (sessionOpening) {
         switchState = SwitchState.PENDING;
         return;
       } else {
         switchState = SwitchState.IN_PROGRESS;
       }
 
       Logging.d(TAG, "switchCamera: Stopping session");
       cameraStatistics.release();
@@ skipping 10 matching lines @@
       int cameraNameIndex = Arrays.asList(deviceNames).indexOf(cameraName);
       cameraName = deviceNames[(cameraNameIndex + 1) % deviceNames.length];
 
       sessionOpening = true;
       openAttemptsRemaining = 1;
       createSessionInternal(0);
     }
     Logging.d(TAG, "switchCamera done");
   }
 
+  private void reportUpdateMediaRecorderError(
+      String error, MediaRecorderHandler mediaRecoderEventsHandler) {
+    checkIsOnCameraThread();
+    Logging.e(TAG, error);
+    if (mediaRecoderEventsHandler != null) {
+      mediaRecoderEventsHandler.onMediaRecorderError(error);
+    }
+  }
+
+  private void updateMediaRecorderInternal(boolean addMediaRecorder, MediaRecorder mediaRecorder,

[magjed_webrtc, 2017/04/22 08:41:52]

I would prefer to not have |addMediaRecorder| as an argument and instead have:
final boolean addMediaRecorder = (mediaRecorder != null);
in this function.

[AlexG, 2017/04/25 23:11:52]

Done.

+      MediaRecorderHandler mediaRecoderEventsHandler) {
+    checkIsOnCameraThread();
+    Logging.d(TAG,
+        "updateMediaRecoderInternal internal. State: " + mediaRecorderState
+            + ". Switch state: " + switchState + ". Add MediaRecorder: " + addMediaRecorder);
+
+    synchronized (stateLock) {
+      if ((addMediaRecorder && mediaRecorderState != MediaRecorderState.IDLE)
+          || (!addMediaRecorder && mediaRecorderState != MediaRecorderState.ACTIVE)) {
+        reportUpdateMediaRecorderError(
+            "Incorrect state for MediaRecorder update.", mediaRecoderEventsHandler);
+        return;
+      }
+      if (switchState != SwitchState.IDLE) {
+        reportUpdateMediaRecorderError(
+            "MediaRecorder update while camera is switching.", mediaRecoderEventsHandler);
+        return;
+      }
+      if (sessionOpening) {
+        reportUpdateMediaRecorderError(
+            "MediaRecorder update while camera is still opening.", mediaRecoderEventsHandler);
+        return;
+      }
+
+      this.mediaRecorderEventsHandler = mediaRecoderEventsHandler;
+      if (addMediaRecorder) {

[magjed_webrtc, 2017/04/22 08:41:52]

I would like to move 'this.mediaRecorder = mediaRecorder;' outside this
if-statement.

[AlexG, 2017/04/25 23:11:52]

Done.

+        this.mediaRecorder = mediaRecorder;
+        mediaRecorderState = MediaRecorderState.IDLE_TO_ACTIVE;
+      } else {
+        this.mediaRecorder = null;
+        mediaRecorderState = MediaRecorderState.ACTIVE_TO_IDLE;
+      }
+
+      Logging.d(TAG, "updateMediaRecoder: Stopping session");

[magjed_webrtc, 2017/04/22 08:41:52]

The documentation for addMediaRecorderToCamera says:  "This can only be called
while the camera is running.", but we never check if 'currentSession != null'
here, and we will actually crash if currentSession is null. So we should
probably call reportUpdateMediaRecorderError for that case.

However, would it be interesting to support the use case when the MediaRecorder
is added before the call to startCapture? I.e. support this:
capturer.addMediaRecorderToCamera(...);
capturer.startCapture(...);
That wouldn't require restarting the session and will save some time. It looks
like you can just return here if currentSession is null in order to support it.

[AlexG, 2017/04/25 23:11:52]

Done.

Yes, this case mat be supported as well, but I suggest to consider it later.
This may be a complex use case since it passes more responsibility from app to
WebRTC layer. It may also have some bad impact on power usage, since full
MediaRecorder preparation need to be done before it can be added to camera and
it keeping non released MEdiaRecorder for a log time may increase power/memory
usage

+      cameraStatistics.release();
+      cameraStatistics = null;
+      final CameraSession oldSession = currentSession;
+      cameraThreadHandler.post(new Runnable() {
+        @Override
+        public void run() {
+          oldSession.stop();
+        }
+      });
+      currentSession = null;
+
+      sessionOpening = true;
+      openAttemptsRemaining = 1;
+      createSessionInternal(0);
+    }
+    Logging.d(TAG, "updateMediaRecoderInternal done");
+  }
+
   private void checkIsOnCameraThread() {
     if (Thread.currentThread() != cameraThreadHandler.getLooper().getThread()) {
       Logging.e(TAG, "Check is on camera thread failed.");
       throw new RuntimeException("Not on camera thread.");
     }
   }
 
   protected String getCameraName() {
     synchronized (stateLock) {
       return cameraName;
     }
   }
 
   abstract protected void createCameraSession(
       CameraSession.CreateSessionCallback createSessionCallback, CameraSession.Events events,
-      Context applicationContext, SurfaceTextureHelper surfaceTextureHelper, String cameraName,
-      int width, int height, int framerate);
+      Context applicationContext, SurfaceTextureHelper surfaceTextureHelper,
+      MediaRecorder mediaRecoder, String cameraName, int width, int height, int framerate);
 }