Android Video Capture: Added static methods for device & capabilities enumeration using Camera2 API

media/base/android/java/src/org/chromium/media/VideoCaptureAndroid2.java

+// Copyright 2014 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+package org.chromium.media;
+
+import android.content.Context;
+import android.hardware.camera2.CameraAccessException;
+import android.hardware.camera2.CameraCharacteristics;
+import android.hardware.camera2.CameraManager;
+import android.hardware.camera2.params.StreamConfigurationMap;
+import android.util.Log;
+import android.util.Size;
+
+import org.chromium.base.JNINamespace;
+
+import java.util.ArrayList;
+import java.util.Arrays;
+
+/**
+ * Static methods to retrieve information on current system cameras and their
+ * capabilities using the Camera2 API introduced in Android SDK 21 (L Release).
+ * For this we interact with an android.hardware.camera2.CameraManager.
+ **/
+@JNINamespace("media")
+public class VideoCaptureAndroid2 {
+    private static final double kNanoSecondsToFps = 1.0E-9;
+    private static final String TAG = "VideoCaptureAndroid2";
+
+    // Service function to grab CameraCharacteristics and handle exceptions.
+    private static CameraCharacteristics getCameraCharacteristics(Context appContext, int id) {
+        final CameraManager manager =
+                (CameraManager) appContext.getSystemService(Context.CAMERA_SERVICE);
+        CameraCharacteristics cameraCharacteristics;

[qinmin, 2014/10/24 22:53:22]

can we just do the following: 

try {
  return manager.getCameraCharacteristics(Integer.toString(id));
} catch(CameraAccessException ex) {
}
return null

[mcasas, 2014/10/25 17:46:16]

Done.

+        try {
+            cameraCharacteristics = manager.getCameraCharacteristics(Integer.toString(id));
+        } catch (CameraAccessException ex) {
+            Log.e(TAG, "getNumberOfCameras: getCameraIdList(): " + ex);
+            return null;
+        }
+        return cameraCharacteristics;
+    }
+
+    static int getNumberOfCameras(Context appContext) {
+        final CameraManager manager =
+                (CameraManager) appContext.getSystemService(Context.CAMERA_SERVICE);
+        try {
+            return manager.getCameraIdList().length;
+        } catch (CameraAccessException ex) {
+            Log.e(TAG, "getNumberOfCameras: getCameraIdList(): " + ex);
+            return 0;
+        }
+    }
+
+    static String getName(int id, Context appContext) {
+        final CameraCharacteristics cameraCharacteristics =
+                getCameraCharacteristics(appContext, id);
+        if (cameraCharacteristics == null) return null;
+        int facing = cameraCharacteristics.get(CameraCharacteristics.LENS_FACING);
+
+        return "camera2 " + id + ", facing "
+                + ((facing == CameraCharacteristics.LENS_FACING_FRONT) ? "front" : "back");
+    }
+
+    static VideoCapture.CaptureFormat[] getDeviceSupportedFormats(Context appContext, int id) {
+        CameraCharacteristics cameraCharacteristics = getCameraCharacteristics(appContext, id);

[qinmin, 2014/10/24 22:53:22]

final

[mcasas, 2014/10/25 17:46:15]

Done.

+        if (cameraCharacteristics == null) return null;
+
+        int[] capabilities = cameraCharacteristics.get(
+                CameraCharacteristics.REQUEST_AVAILABLE_CAPABILITIES);
+        // Per-format frame rate via getOutputMinFrameDuration() is only available if the
+        // property REQUEST_AVAILABLE_CAPABILITIES_MANUAL_SENSOR is set.
+        final boolean minFrameDurationAvailable = Arrays.asList(capabilities).contains(
+                CameraCharacteristics.REQUEST_AVAILABLE_CAPABILITIES_MANUAL_SENSOR);
+
+        ArrayList<VideoCapture.CaptureFormat> formatList =
+                new ArrayList<VideoCapture.CaptureFormat>();
+        StreamConfigurationMap streamMap =
+                cameraCharacteristics.get(CameraCharacteristics.SCALER_STREAM_CONFIGURATION_MAP);
+        final int[] formats = streamMap.getOutputFormats();
+        for (int format : formats) {
+            final Size[] sizes = streamMap.getOutputSizes(format);
+            for (Size size : sizes) {
+                double minFrameRate = 0.0f;
+                if (minFrameDurationAvailable) {
+                    final long minFrameDuration =
+                            streamMap.getOutputMinFrameDuration(format, size);
+                    minFrameRate = (minFrameDuration == 0) ? 0.0f :
+                            (1.0 / kNanoSecondsToFps * minFrameDuration);
+                } else {
+                    // TODO(mcasas): find out where to get the info from in this case.
+                    // Hint: perhaps using SCALER_AVAILABLE_PROCESSED_MIN_DURATIONS.
+                    minFrameRate = 0.0;
+                }
+                formatList.add(new VideoCapture.CaptureFormat(size.getWidth(),
+                                                              size.getHeight(),
+                                                              (int) minFrameRate,
+                                                              0));
+            }
+        }
+        return formatList.toArray(new VideoCapture.CaptureFormat[formatList.size()]);
+    }
+
+    VideoCaptureAndroid2() {}
+}