sdk/android/src/java/org/webrtc/Camera2Session.java - src.git - Git at Google

 /*
  *  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.hardware.camera2.CameraAccessException;
 import android.hardware.camera2.CameraCaptureSession;
 import android.hardware.camera2.CameraCharacteristics;
 import android.hardware.camera2.CameraDevice;
 import android.hardware.camera2.CameraManager;
 import android.hardware.camera2.CameraMetadata;
 import android.hardware.camera2.CaptureFailure;
 import android.hardware.camera2.CaptureRequest;
 import android.os.Handler;
 import android.util.Range;
 import android.view.Surface;
 import androidx.annotation.Nullable;
 import java.util.Arrays;
 import java.util.List;
 import java.util.concurrent.TimeUnit;
 import org.webrtc.CameraEnumerationAndroid.CaptureFormat;

 class Camera2Session implements CameraSession {
   private static final String TAG = "Camera2Session";

   private static final Histogram camera2StartTimeMsHistogram =
       Histogram.createCounts("WebRTC.Android.Camera2.StartTimeMs", 1, 10000, 50);
   private static final Histogram camera2StopTimeMsHistogram =
       Histogram.createCounts("WebRTC.Android.Camera2.StopTimeMs", 1, 10000, 50);
   private static final Histogram camera2ResolutionHistogram = Histogram.createEnumeration(
       "WebRTC.Android.Camera2.Resolution", CameraEnumerationAndroid.COMMON_RESOLUTIONS.size());

   private static enum SessionState { RUNNING, STOPPED }

   private final Handler cameraThreadHandler;
   private final CreateSessionCallback callback;
   private final Events events;
   private final Context applicationContext;
   private final CameraManager cameraManager;
   private final SurfaceTextureHelper surfaceTextureHelper;
   private final String cameraId;
   private final int width;
   private final int height;
   private final int framerate;

   // Initialized at start
   private CameraCharacteristics cameraCharacteristics;
   private int cameraOrientation;
   private boolean isCameraFrontFacing;
   private int fpsUnitFactor;
   private CaptureFormat captureFormat;

   // Initialized when camera opens
   @Nullable private CameraDevice cameraDevice;
   @Nullable private Surface surface;

   // Initialized when capture session is created
   @Nullable private CameraCaptureSession captureSession;

   // State
   private SessionState state = SessionState.RUNNING;
   private boolean firstFrameReported;

   // Used only for stats. Only used on the camera thread.
   private final long constructionTimeNs; // Construction time of this class.

   private class CameraStateCallback extends CameraDevice.StateCallback {
     private String getErrorDescription(int errorCode) {
       switch (errorCode) {
         case CameraDevice.StateCallback.ERROR_CAMERA_DEVICE:
           return "Camera device has encountered a fatal error.";
         case CameraDevice.StateCallback.ERROR_CAMERA_DISABLED:
           return "Camera device could not be opened due to a device policy.";
         case CameraDevice.StateCallback.ERROR_CAMERA_IN_USE:
           return "Camera device is in use already.";
         case CameraDevice.StateCallback.ERROR_CAMERA_SERVICE:
           return "Camera service has encountered a fatal error.";
         case CameraDevice.StateCallback.ERROR_MAX_CAMERAS_IN_USE:
           return "Camera device could not be opened because"
               + " there are too many other open camera devices.";
         default:
           return "Unknown camera error: " + errorCode;
       }
     }

     @Override
     public void onDisconnected(CameraDevice camera) {
       checkIsOnCameraThread();
       final boolean startFailure = (captureSession == null) && (state != SessionState.STOPPED);
       state = SessionState.STOPPED;
       stopInternal();
       if (startFailure) {
         callback.onFailure(FailureType.DISCONNECTED, "Camera disconnected / evicted.");
       } else {
         events.onCameraDisconnected(Camera2Session.this);
       }
     }

     @Override
     public void onError(CameraDevice camera, int errorCode) {
       checkIsOnCameraThread();
       reportError(getErrorDescription(errorCode));
     }

     @Override
     public void onOpened(CameraDevice camera) {
       checkIsOnCameraThread();

       Logging.d(TAG, "Camera opened.");
       cameraDevice = camera;

       surfaceTextureHelper.setTextureSize(captureFormat.width, captureFormat.height);
       surface = new Surface(surfaceTextureHelper.getSurfaceTexture());
       try {
         camera.createCaptureSession(
             Arrays.asList(surface), new CaptureSessionCallback(), cameraThreadHandler);
       } catch (CameraAccessException e) {
         reportError("Failed to create capture session. " + e);
         return;
       }
     }

     @Override
     public void onClosed(CameraDevice camera) {
       checkIsOnCameraThread();

       Logging.d(TAG, "Camera device closed.");
       events.onCameraClosed(Camera2Session.this);
     }
   }

   private class CaptureSessionCallback extends CameraCaptureSession.StateCallback {
     @Override
     public void onConfigureFailed(CameraCaptureSession session) {
       checkIsOnCameraThread();
       session.close();
       reportError("Failed to configure capture session.");
     }

     @Override
     public void onConfigured(CameraCaptureSession session) {
       checkIsOnCameraThread();
       Logging.d(TAG, "Camera capture session configured.");
       captureSession = session;
       try {
         /*
          * The viable options for video capture requests are:
          * TEMPLATE_PREVIEW: High frame rate is given priority over the highest-quality
          *   post-processing.
          * TEMPLATE_RECORD: Stable frame rate is used, and post-processing is set for recording
          *   quality.
          */
         final CaptureRequest.Builder captureRequestBuilder =
             cameraDevice.createCaptureRequest(CameraDevice.TEMPLATE_RECORD);
         // Set auto exposure fps range.
         captureRequestBuilder.set(CaptureRequest.CONTROL_AE_TARGET_FPS_RANGE,
             new Range<Integer>(captureFormat.framerate.min / fpsUnitFactor,
                 captureFormat.framerate.max / fpsUnitFactor));
         captureRequestBuilder.set(
             CaptureRequest.CONTROL_AE_MODE, CaptureRequest.CONTROL_AE_MODE_ON);
         captureRequestBuilder.set(CaptureRequest.CONTROL_AE_LOCK, false);
         chooseStabilizationMode(captureRequestBuilder);
         chooseFocusMode(captureRequestBuilder);

         captureRequestBuilder.addTarget(surface);
         session.setRepeatingRequest(
             captureRequestBuilder.build(), new CameraCaptureCallback(), cameraThreadHandler);
       } catch (CameraAccessException e) {
         reportError("Failed to start capture request. " + e);
         return;
       }

       surfaceTextureHelper.startListening((VideoFrame frame) -> {
         checkIsOnCameraThread();

         if (state != SessionState.RUNNING) {
           Logging.d(TAG, "Texture frame captured but camera is no longer running.");
           return;
         }

         if (!firstFrameReported) {
           firstFrameReported = true;
           final int startTimeMs =
               (int) TimeUnit.NANOSECONDS.toMillis(System.nanoTime() - constructionTimeNs);
           camera2StartTimeMsHistogram.addSample(startTimeMs);
         }

         // Undo the mirror that the OS "helps" us with.
         // http://developer.android.com/reference/android/hardware/Camera.html#setDisplayOrientation(int)
         // Also, undo camera orientation, we report it as rotation instead.
         final VideoFrame modifiedFrame =
             new VideoFrame(CameraSession.createTextureBufferWithModifiedTransformMatrix(
                                (TextureBufferImpl) frame.getBuffer(),
                                /* mirror= */ isCameraFrontFacing,
                                /* rotation= */ -cameraOrientation),
                 /* rotation= */ getFrameOrientation(), frame.getTimestampNs());
         events.onFrameCaptured(Camera2Session.this, modifiedFrame);
         modifiedFrame.release();
       });
       Logging.d(TAG, "Camera device successfully started.");
       callback.onDone(Camera2Session.this);
     }

     // Prefers optical stabilization over software stabilization if available. Only enables one of
     // the stabilization modes at a time because having both enabled can cause strange results.
     private void chooseStabilizationMode(CaptureRequest.Builder captureRequestBuilder) {
       final int[] availableOpticalStabilization = cameraCharacteristics.get(
           CameraCharacteristics.LENS_INFO_AVAILABLE_OPTICAL_STABILIZATION);
       if (availableOpticalStabilization != null) {
         for (int mode : availableOpticalStabilization) {
           if (mode == CaptureRequest.LENS_OPTICAL_STABILIZATION_MODE_ON) {
             captureRequestBuilder.set(CaptureRequest.LENS_OPTICAL_STABILIZATION_MODE,
                 CaptureRequest.LENS_OPTICAL_STABILIZATION_MODE_ON);
             captureRequestBuilder.set(CaptureRequest.CONTROL_VIDEO_STABILIZATION_MODE,
                 CaptureRequest.CONTROL_VIDEO_STABILIZATION_MODE_OFF);
             Logging.d(TAG, "Using optical stabilization.");
             return;
           }
         }
       }
       // If no optical mode is available, try software.
       final int[] availableVideoStabilization = cameraCharacteristics.get(
           CameraCharacteristics.CONTROL_AVAILABLE_VIDEO_STABILIZATION_MODES);
       if (availableVideoStabilization != null) {
         for (int mode : availableVideoStabilization) {
           if (mode == CaptureRequest.CONTROL_VIDEO_STABILIZATION_MODE_ON) {
             captureRequestBuilder.set(CaptureRequest.CONTROL_VIDEO_STABILIZATION_MODE,
                 CaptureRequest.CONTROL_VIDEO_STABILIZATION_MODE_ON);
             captureRequestBuilder.set(CaptureRequest.LENS_OPTICAL_STABILIZATION_MODE,
                 CaptureRequest.LENS_OPTICAL_STABILIZATION_MODE_OFF);
             Logging.d(TAG, "Using video stabilization.");
             return;
           }
         }
       }
       Logging.d(TAG, "Stabilization not available.");
     }

     private void chooseFocusMode(CaptureRequest.Builder captureRequestBuilder) {
       final int[] availableFocusModes =
           cameraCharacteristics.get(CameraCharacteristics.CONTROL_AF_AVAILABLE_MODES);
       for (int mode : availableFocusModes) {
         if (mode == CaptureRequest.CONTROL_AF_MODE_CONTINUOUS_VIDEO) {
           captureRequestBuilder.set(
               CaptureRequest.CONTROL_AF_MODE, CaptureRequest.CONTROL_AF_MODE_CONTINUOUS_VIDEO);
           Logging.d(TAG, "Using continuous video auto-focus.");
           return;
         }
       }
       Logging.d(TAG, "Auto-focus is not available.");
     }
   }

   private static class CameraCaptureCallback extends CameraCaptureSession.CaptureCallback {
     @Override
     public void onCaptureFailed(
         CameraCaptureSession session, CaptureRequest request, CaptureFailure failure) {
       Logging.d(TAG, "Capture failed: " + failure);
     }
   }

   public static void create(CreateSessionCallback callback, Events events,
       Context applicationContext, CameraManager cameraManager,
       SurfaceTextureHelper surfaceTextureHelper, String cameraId, int width, int height,
       int framerate) {
     new Camera2Session(callback, events, applicationContext, cameraManager, surfaceTextureHelper,
         cameraId, width, height, framerate);
   }

   private Camera2Session(CreateSessionCallback callback, Events events, Context applicationContext,
       CameraManager cameraManager, SurfaceTextureHelper surfaceTextureHelper, String cameraId,
       int width, int height, int framerate) {
     Logging.d(TAG, "Create new camera2 session on camera " + cameraId);

     constructionTimeNs = System.nanoTime();

     this.cameraThreadHandler = new Handler();
     this.callback = callback;
     this.events = events;
     this.applicationContext = applicationContext;
     this.cameraManager = cameraManager;
     this.surfaceTextureHelper = surfaceTextureHelper;
     this.cameraId = cameraId;
     this.width = width;
     this.height = height;
     this.framerate = framerate;

     start();
   }

   private void start() {
     checkIsOnCameraThread();
     Logging.d(TAG, "start");

     try {
       cameraCharacteristics = cameraManager.getCameraCharacteristics(cameraId);
     } catch (CameraAccessException | IllegalArgumentException e) {
       reportError("getCameraCharacteristics(): " + e.getMessage());
       return;
     }
     cameraOrientation = cameraCharacteristics.get(CameraCharacteristics.SENSOR_ORIENTATION);
     isCameraFrontFacing = cameraCharacteristics.get(CameraCharacteristics.LENS_FACING)
         == CameraMetadata.LENS_FACING_FRONT;

     findCaptureFormat();

     if (captureFormat == null) {
       // findCaptureFormat reports an error already.
       return;
     }

     openCamera();
   }

   private void findCaptureFormat() {
     checkIsOnCameraThread();

     Range<Integer>[] fpsRanges =
         cameraCharacteristics.get(CameraCharacteristics.CONTROL_AE_AVAILABLE_TARGET_FPS_RANGES);
     fpsUnitFactor = Camera2Enumerator.getFpsUnitFactor(fpsRanges);
     List<CaptureFormat.FramerateRange> framerateRanges =
         Camera2Enumerator.convertFramerates(fpsRanges, fpsUnitFactor);
     List<Size> sizes = Camera2Enumerator.getSupportedSizes(cameraCharacteristics);
     Logging.d(TAG, "Available preview sizes: " + sizes);
     Logging.d(TAG, "Available fps ranges: " + framerateRanges);

     if (framerateRanges.isEmpty() || sizes.isEmpty()) {
       reportError("No supported capture formats.");
       return;
     }

     final CaptureFormat.FramerateRange bestFpsRange =
         CameraEnumerationAndroid.getClosestSupportedFramerateRange(framerateRanges, framerate);

     final Size bestSize = CameraEnumerationAndroid.getClosestSupportedSize(sizes, width, height);
     CameraEnumerationAndroid.reportCameraResolution(camera2ResolutionHistogram, bestSize);

     captureFormat = new CaptureFormat(bestSize.width, bestSize.height, bestFpsRange);
     Logging.d(TAG, "Using capture format: " + captureFormat);
   }

   private void openCamera() {
     checkIsOnCameraThread();

     Logging.d(TAG, "Opening camera " + cameraId);
     events.onCameraOpening();

     try {
       cameraManager.openCamera(cameraId, new CameraStateCallback(), cameraThreadHandler);
     } catch (CameraAccessException | IllegalArgumentException | SecurityException e) {
       reportError("Failed to open camera: " + e);
       return;
     }
   }

   @Override
   public void stop() {
     Logging.d(TAG, "Stop camera2 session on camera " + cameraId);
     checkIsOnCameraThread();
     if (state != SessionState.STOPPED) {
       final long stopStartTime = System.nanoTime();
       state = SessionState.STOPPED;
       stopInternal();
       final int stopTimeMs = (int) TimeUnit.NANOSECONDS.toMillis(System.nanoTime() - stopStartTime);
       camera2StopTimeMsHistogram.addSample(stopTimeMs);
     }
   }

   private void stopInternal() {
     Logging.d(TAG, "Stop internal");
     checkIsOnCameraThread();

     surfaceTextureHelper.stopListening();

     if (captureSession != null) {
       captureSession.close();
       captureSession = null;
     }
     if (surface != null) {
       surface.release();
       surface = null;
     }
     if (cameraDevice != null) {
       cameraDevice.close();
       cameraDevice = null;
     }

     Logging.d(TAG, "Stop done");
   }

   private void reportError(String error) {
     checkIsOnCameraThread();
     Logging.e(TAG, "Error: " + error);

     final boolean startFailure = (captureSession == null) && (state != SessionState.STOPPED);
     state = SessionState.STOPPED;
     stopInternal();
     if (startFailure) {
       callback.onFailure(FailureType.ERROR, error);
     } else {
       events.onCameraError(this, error);
     }
   }

   private int getFrameOrientation() {
     int rotation = CameraSession.getDeviceOrientation(applicationContext);
     if (!isCameraFrontFacing) {
       rotation = 360 - rotation;
     }
     return (cameraOrientation + rotation) % 360;
   }

   private void checkIsOnCameraThread() {
     if (Thread.currentThread() != cameraThreadHandler.getLooper().getThread()) {
       throw new IllegalStateException("Wrong thread");
     }
   }
 }
	/*
	* 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.hardware.camera2.CameraAccessException;
	import android.hardware.camera2.CameraCaptureSession;
	import android.hardware.camera2.CameraCharacteristics;
	import android.hardware.camera2.CameraDevice;
	import android.hardware.camera2.CameraManager;
	import android.hardware.camera2.CameraMetadata;
	import android.hardware.camera2.CaptureFailure;
	import android.hardware.camera2.CaptureRequest;
	import android.os.Handler;
	import android.util.Range;
	import android.view.Surface;
	import androidx.annotation.Nullable;
	import java.util.Arrays;
	import java.util.List;
	import java.util.concurrent.TimeUnit;
	import org.webrtc.CameraEnumerationAndroid.CaptureFormat;

	class Camera2Session implements CameraSession {
	private static final String TAG = "Camera2Session";

	private static final Histogram camera2StartTimeMsHistogram =
	Histogram.createCounts("WebRTC.Android.Camera2.StartTimeMs", 1, 10000, 50);
	private static final Histogram camera2StopTimeMsHistogram =
	Histogram.createCounts("WebRTC.Android.Camera2.StopTimeMs", 1, 10000, 50);
	private static final Histogram camera2ResolutionHistogram = Histogram.createEnumeration(
	"WebRTC.Android.Camera2.Resolution", CameraEnumerationAndroid.COMMON_RESOLUTIONS.size());

	private static enum SessionState { RUNNING, STOPPED }

	private final Handler cameraThreadHandler;
	private final CreateSessionCallback callback;
	private final Events events;
	private final Context applicationContext;
	private final CameraManager cameraManager;
	private final SurfaceTextureHelper surfaceTextureHelper;
	private final String cameraId;
	private final int width;
	private final int height;
	private final int framerate;

	// Initialized at start
	private CameraCharacteristics cameraCharacteristics;
	private int cameraOrientation;
	private boolean isCameraFrontFacing;
	private int fpsUnitFactor;
	private CaptureFormat captureFormat;

	// Initialized when camera opens
	@Nullable private CameraDevice cameraDevice;
	@Nullable private Surface surface;

	// Initialized when capture session is created
	@Nullable private CameraCaptureSession captureSession;

	// State
	private SessionState state = SessionState.RUNNING;
	private boolean firstFrameReported;

	// Used only for stats. Only used on the camera thread.
	private final long constructionTimeNs; // Construction time of this class.

	private class CameraStateCallback extends CameraDevice.StateCallback {
	private String getErrorDescription(int errorCode) {
	switch (errorCode) {
	case CameraDevice.StateCallback.ERROR_CAMERA_DEVICE:
	return "Camera device has encountered a fatal error.";
	case CameraDevice.StateCallback.ERROR_CAMERA_DISABLED:
	return "Camera device could not be opened due to a device policy.";
	case CameraDevice.StateCallback.ERROR_CAMERA_IN_USE:
	return "Camera device is in use already.";
	case CameraDevice.StateCallback.ERROR_CAMERA_SERVICE:
	return "Camera service has encountered a fatal error.";
	case CameraDevice.StateCallback.ERROR_MAX_CAMERAS_IN_USE:
	return "Camera device could not be opened because"
	+ " there are too many other open camera devices.";
	default:
	return "Unknown camera error: " + errorCode;
	}
	}

	@Override
	public void onDisconnected(CameraDevice camera) {
	checkIsOnCameraThread();
	final boolean startFailure = (captureSession == null) && (state != SessionState.STOPPED);
	state = SessionState.STOPPED;
	stopInternal();
	if (startFailure) {
	callback.onFailure(FailureType.DISCONNECTED, "Camera disconnected / evicted.");
	} else {
	events.onCameraDisconnected(Camera2Session.this);
	}
	}

	@Override
	public void onError(CameraDevice camera, int errorCode) {
	checkIsOnCameraThread();
	reportError(getErrorDescription(errorCode));
	}

	@Override
	public void onOpened(CameraDevice camera) {
	checkIsOnCameraThread();

	Logging.d(TAG, "Camera opened.");
	cameraDevice = camera;

	surfaceTextureHelper.setTextureSize(captureFormat.width, captureFormat.height);
	surface = new Surface(surfaceTextureHelper.getSurfaceTexture());
	try {
	camera.createCaptureSession(
	Arrays.asList(surface), new CaptureSessionCallback(), cameraThreadHandler);
	} catch (CameraAccessException e) {
	reportError("Failed to create capture session. " + e);
	return;
	}
	}

	@Override
	public void onClosed(CameraDevice camera) {
	checkIsOnCameraThread();

	Logging.d(TAG, "Camera device closed.");
	events.onCameraClosed(Camera2Session.this);
	}
	}

	private class CaptureSessionCallback extends CameraCaptureSession.StateCallback {
	@Override
	public void onConfigureFailed(CameraCaptureSession session) {
	checkIsOnCameraThread();
	session.close();
	reportError("Failed to configure capture session.");
	}

	@Override
	public void onConfigured(CameraCaptureSession session) {
	checkIsOnCameraThread();
	Logging.d(TAG, "Camera capture session configured.");
	captureSession = session;
	try {
	/*
	* The viable options for video capture requests are:
	* TEMPLATE_PREVIEW: High frame rate is given priority over the highest-quality
	* post-processing.
	* TEMPLATE_RECORD: Stable frame rate is used, and post-processing is set for recording
	* quality.
	*/
	final CaptureRequest.Builder captureRequestBuilder =
	cameraDevice.createCaptureRequest(CameraDevice.TEMPLATE_RECORD);
	// Set auto exposure fps range.
	captureRequestBuilder.set(CaptureRequest.CONTROL_AE_TARGET_FPS_RANGE,
	new Range<Integer>(captureFormat.framerate.min / fpsUnitFactor,
	captureFormat.framerate.max / fpsUnitFactor));
	captureRequestBuilder.set(
	CaptureRequest.CONTROL_AE_MODE, CaptureRequest.CONTROL_AE_MODE_ON);
	captureRequestBuilder.set(CaptureRequest.CONTROL_AE_LOCK, false);
	chooseStabilizationMode(captureRequestBuilder);
	chooseFocusMode(captureRequestBuilder);

	captureRequestBuilder.addTarget(surface);
	session.setRepeatingRequest(
	captureRequestBuilder.build(), new CameraCaptureCallback(), cameraThreadHandler);
	} catch (CameraAccessException e) {
	reportError("Failed to start capture request. " + e);
	return;
	}

	surfaceTextureHelper.startListening((VideoFrame frame) -> {
	checkIsOnCameraThread();

	if (state != SessionState.RUNNING) {
	Logging.d(TAG, "Texture frame captured but camera is no longer running.");
	return;
	}

	if (!firstFrameReported) {
	firstFrameReported = true;
	final int startTimeMs =
	(int) TimeUnit.NANOSECONDS.toMillis(System.nanoTime() - constructionTimeNs);
	camera2StartTimeMsHistogram.addSample(startTimeMs);
	}

	// Undo the mirror that the OS "helps" us with.
	// http://developer.android.com/reference/android/hardware/Camera.html#setDisplayOrientation(int)
	// Also, undo camera orientation, we report it as rotation instead.
	final VideoFrame modifiedFrame =
	new VideoFrame(CameraSession.createTextureBufferWithModifiedTransformMatrix(
	(TextureBufferImpl) frame.getBuffer(),
	/* mirror= */ isCameraFrontFacing,
	/* rotation= */ -cameraOrientation),
	/* rotation= */ getFrameOrientation(), frame.getTimestampNs());
	events.onFrameCaptured(Camera2Session.this, modifiedFrame);
	modifiedFrame.release();
	});
	Logging.d(TAG, "Camera device successfully started.");
	callback.onDone(Camera2Session.this);
	}

	// Prefers optical stabilization over software stabilization if available. Only enables one of
	// the stabilization modes at a time because having both enabled can cause strange results.
	private void chooseStabilizationMode(CaptureRequest.Builder captureRequestBuilder) {
	final int[] availableOpticalStabilization = cameraCharacteristics.get(
	CameraCharacteristics.LENS_INFO_AVAILABLE_OPTICAL_STABILIZATION);
	if (availableOpticalStabilization != null) {
	for (int mode : availableOpticalStabilization) {
	if (mode == CaptureRequest.LENS_OPTICAL_STABILIZATION_MODE_ON) {
	captureRequestBuilder.set(CaptureRequest.LENS_OPTICAL_STABILIZATION_MODE,
	CaptureRequest.LENS_OPTICAL_STABILIZATION_MODE_ON);
	captureRequestBuilder.set(CaptureRequest.CONTROL_VIDEO_STABILIZATION_MODE,
	CaptureRequest.CONTROL_VIDEO_STABILIZATION_MODE_OFF);
	Logging.d(TAG, "Using optical stabilization.");
	return;
	}
	}
	}
	// If no optical mode is available, try software.
	final int[] availableVideoStabilization = cameraCharacteristics.get(
	CameraCharacteristics.CONTROL_AVAILABLE_VIDEO_STABILIZATION_MODES);
	if (availableVideoStabilization != null) {
	for (int mode : availableVideoStabilization) {
	if (mode == CaptureRequest.CONTROL_VIDEO_STABILIZATION_MODE_ON) {
	captureRequestBuilder.set(CaptureRequest.CONTROL_VIDEO_STABILIZATION_MODE,
	CaptureRequest.CONTROL_VIDEO_STABILIZATION_MODE_ON);
	captureRequestBuilder.set(CaptureRequest.LENS_OPTICAL_STABILIZATION_MODE,
	CaptureRequest.LENS_OPTICAL_STABILIZATION_MODE_OFF);
	Logging.d(TAG, "Using video stabilization.");
	return;
	}
	}
	}
	Logging.d(TAG, "Stabilization not available.");
	}

	private void chooseFocusMode(CaptureRequest.Builder captureRequestBuilder) {
	final int[] availableFocusModes =
	cameraCharacteristics.get(CameraCharacteristics.CONTROL_AF_AVAILABLE_MODES);
	for (int mode : availableFocusModes) {
	if (mode == CaptureRequest.CONTROL_AF_MODE_CONTINUOUS_VIDEO) {
	captureRequestBuilder.set(
	CaptureRequest.CONTROL_AF_MODE, CaptureRequest.CONTROL_AF_MODE_CONTINUOUS_VIDEO);
	Logging.d(TAG, "Using continuous video auto-focus.");
	return;
	}
	}
	Logging.d(TAG, "Auto-focus is not available.");
	}
	}

	private static class CameraCaptureCallback extends CameraCaptureSession.CaptureCallback {
	@Override
	public void onCaptureFailed(
	CameraCaptureSession session, CaptureRequest request, CaptureFailure failure) {
	Logging.d(TAG, "Capture failed: " + failure);
	}
	}

	public static void create(CreateSessionCallback callback, Events events,
	Context applicationContext, CameraManager cameraManager,
	SurfaceTextureHelper surfaceTextureHelper, String cameraId, int width, int height,
	int framerate) {
	new Camera2Session(callback, events, applicationContext, cameraManager, surfaceTextureHelper,
	cameraId, width, height, framerate);
	}

	private Camera2Session(CreateSessionCallback callback, Events events, Context applicationContext,
	CameraManager cameraManager, SurfaceTextureHelper surfaceTextureHelper, String cameraId,
	int width, int height, int framerate) {
	Logging.d(TAG, "Create new camera2 session on camera " + cameraId);

	constructionTimeNs = System.nanoTime();

	this.cameraThreadHandler = new Handler();
	this.callback = callback;
	this.events = events;
	this.applicationContext = applicationContext;
	this.cameraManager = cameraManager;
	this.surfaceTextureHelper = surfaceTextureHelper;
	this.cameraId = cameraId;
	this.width = width;
	this.height = height;
	this.framerate = framerate;

	start();
	}

	private void start() {
	checkIsOnCameraThread();
	Logging.d(TAG, "start");

	try {
	cameraCharacteristics = cameraManager.getCameraCharacteristics(cameraId);
	} catch (CameraAccessException \| IllegalArgumentException e) {
	reportError("getCameraCharacteristics(): " + e.getMessage());
	return;
	}
	cameraOrientation = cameraCharacteristics.get(CameraCharacteristics.SENSOR_ORIENTATION);
	isCameraFrontFacing = cameraCharacteristics.get(CameraCharacteristics.LENS_FACING)
	== CameraMetadata.LENS_FACING_FRONT;

	findCaptureFormat();

	if (captureFormat == null) {
	// findCaptureFormat reports an error already.
	return;
	}

	openCamera();
	}

	private void findCaptureFormat() {
	checkIsOnCameraThread();

	Range<Integer>[] fpsRanges =
	cameraCharacteristics.get(CameraCharacteristics.CONTROL_AE_AVAILABLE_TARGET_FPS_RANGES);
	fpsUnitFactor = Camera2Enumerator.getFpsUnitFactor(fpsRanges);
	List<CaptureFormat.FramerateRange> framerateRanges =
	Camera2Enumerator.convertFramerates(fpsRanges, fpsUnitFactor);
	List<Size> sizes = Camera2Enumerator.getSupportedSizes(cameraCharacteristics);
	Logging.d(TAG, "Available preview sizes: " + sizes);
	Logging.d(TAG, "Available fps ranges: " + framerateRanges);

	if (framerateRanges.isEmpty() \|\| sizes.isEmpty()) {
	reportError("No supported capture formats.");
	return;
	}

	final CaptureFormat.FramerateRange bestFpsRange =
	CameraEnumerationAndroid.getClosestSupportedFramerateRange(framerateRanges, framerate);

	final Size bestSize = CameraEnumerationAndroid.getClosestSupportedSize(sizes, width, height);
	CameraEnumerationAndroid.reportCameraResolution(camera2ResolutionHistogram, bestSize);

	captureFormat = new CaptureFormat(bestSize.width, bestSize.height, bestFpsRange);
	Logging.d(TAG, "Using capture format: " + captureFormat);
	}

	private void openCamera() {
	checkIsOnCameraThread();

	Logging.d(TAG, "Opening camera " + cameraId);
	events.onCameraOpening();

	try {
	cameraManager.openCamera(cameraId, new CameraStateCallback(), cameraThreadHandler);
	} catch (CameraAccessException \| IllegalArgumentException \| SecurityException e) {
	reportError("Failed to open camera: " + e);
	return;
	}
	}

	@Override
	public void stop() {
	Logging.d(TAG, "Stop camera2 session on camera " + cameraId);
	checkIsOnCameraThread();
	if (state != SessionState.STOPPED) {
	final long stopStartTime = System.nanoTime();
	state = SessionState.STOPPED;
	stopInternal();
	final int stopTimeMs = (int) TimeUnit.NANOSECONDS.toMillis(System.nanoTime() - stopStartTime);
	camera2StopTimeMsHistogram.addSample(stopTimeMs);
	}
	}

	private void stopInternal() {
	Logging.d(TAG, "Stop internal");
	checkIsOnCameraThread();

	surfaceTextureHelper.stopListening();

	if (captureSession != null) {
	captureSession.close();
	captureSession = null;
	}
	if (surface != null) {
	surface.release();
	surface = null;
	}
	if (cameraDevice != null) {
	cameraDevice.close();
	cameraDevice = null;
	}

	Logging.d(TAG, "Stop done");
	}

	private void reportError(String error) {
	checkIsOnCameraThread();
	Logging.e(TAG, "Error: " + error);

	final boolean startFailure = (captureSession == null) && (state != SessionState.STOPPED);
	state = SessionState.STOPPED;
	stopInternal();
	if (startFailure) {
	callback.onFailure(FailureType.ERROR, error);
	} else {
	events.onCameraError(this, error);
	}
	}

	private int getFrameOrientation() {
	int rotation = CameraSession.getDeviceOrientation(applicationContext);
	if (!isCameraFrontFacing) {
	rotation = 360 - rotation;
	}
	return (cameraOrientation + rotation) % 360;
	}

	private void checkIsOnCameraThread() {
	if (Thread.currentThread() != cameraThreadHandler.getLooper().getThread()) {
	throw new IllegalStateException("Wrong thread");
	}
	}
	}