如何设置EXPOSURE_TIME和FRAME_DURATION，CaptureRequest.Builder.set(CaptureRequest.SENSOR_EXPOSURE_TIME，x)不起作用

Question

我想调整一下Adroid手机的曝光时间和画面时长。我看过一些报纸说Android不提供曝光时间设置API。我试过使用HTC m8x phone，它的摄像头本身支持从4到1/8000的不同曝光时间，所以我猜应该有一些方法可以在应用程序中更改它。

方法get(CaptureRequest.EXPOSURE_TIME)返回null。在我使用CaptureRequest.Builder.set(CaptureRequest.SENSOR_EXPOSURE_TIME,x)之后，CaptureRequest.SENSOR_EXPOSURE_TIME变成了x，但手机中的预览效果并没有改变。

我查看了HTC m8x的权限，代码如下：

Activity activity = getActivity();
CameraManager manager =(CameraManager)activity.getSystemService(Context.CAMERA_SERVICE);
for (String cameraId : manager.getCameraIdList()) {
  CameraCharacteristics characteristics= manager.getCameraCharacteristics(cameraId);
  // We don't use a front facing camera in this sample.
  if (characteristics.get(CameraCharacteristics.LENS_FACING)== CameraCharacteristics.LENS_FACING_FRONT) {
    continue;
  }
  int level =   characteristics.get(CameraCharacteristics.INFO_SUPPORTED_HARDWARE_LEVEL);
  boolean hasFullLevel
                 = (level ==   CameraCharacteristics.INFO_SUPPORTED_HARDWARE_LEVEL_FULL);



  int[] capabilities = characteristics.get(CameraCharacteristics.REQUEST_AVAILABLE_CAPABILITIES);
  int syncLatency = characteristics.get(CameraCharacteristics.SYNC_MAX_LATENCY);
  boolean hasManualControl = hasCapability(capabilities,CameraCharacteristics.REQUEST_AVAILABLE_CAPABILITIES_MANUAL_SENSOR);
  boolean hasEnoughCapability = hasManualControl &&syncLatency == CameraCharacteristics.SYNC_MAX_LATENCY_PER_FRAME_CONTROL;

  // All these are guaranteed by
  // CameraCharacteristics.INFO_SUPPORTED_HARDWARE_LEVEL_FULL, but checking for only
  // the things we care about expands range of devices we can run on
  // We want:
  //  - Back-facing camera
  //  - Manual sensor control
  //  - Per-frame synchronization (so that exposure can be changed every frame)
  if ( hasFullLevel !! hasEnoughCapability) {
    mCameraId = cameraId;
    return;}
  }

没有返回摄像头id。

characteristics.get(CameraCharacteristics.INFO_SUPPORTED_HARDWARE_LEVEL) =2;
CameraCharacteristics.INFO_SUPPORTED_HARDWARE_LEVEL_FULL = 1;
CameraCharacteristics.REQUEST_AVAILABLE_CAPABILITIES_MANUAL_SENSOR = 1;
capabilities =0;
characteristics.get(CameraCharacteristics.SYNC_MAX_LATENCY) =-1
CameraCharacteristics.SYNC_MAX_LATENCY_PER_FRAME_CONTROL = 0;

那么，这是否表明我无权更改HTC m8x手机的曝光时间？启动手机会有帮助吗？

Answer 1

看起来你的手机安装了Android4.x，而新的camera2应用程序接口需要棒棒糖/API21。如果你已经升级到API21，是的，如果它有完全的控制，它会告诉你它确实支持手动曝光控制……如果它的支持有限...

在REQUEST_AVAILABLE_CAPABILITIES_MANUAL_SENSOR上查看你想要的单个控件，比如曝光...

如果它有传统的支持，不，它不支持手动控制。