Enabling Camera Flash While Recording Video

Question

I need a way to control the camera flash on an Android device while it is recording video. I\'m making a strobe light app, and taking videos with a flashing strobe light would r

Answer 1

I encountered a similar issue. The user should be able to change the flash mode during recording to meet their needs depending on the light situation. After some investigative research i came to the following solution:

I assume, that you've already set up a proper SurfaceView and a SurfaceHolder with its necessary callbacks. The first thing i did was providing this code (not declared variables are globals):

public void surfaceCreated(SurfaceHolder holder) {
    try {
        camera = Camera.open();

        parameters = camera.getParameters();
        parameters.setFlashMode(Parameters.FLASH_MODE_OFF);

        camera.setParameters(parameters);
        camera.setPreviewDisplay(holder);
        camera.startPreview();

        recorder = new MediaRecorder();
    } catch (IOException e) {
        e.printStackTrace();
    }       
}

My next step was initializing and preparing the recorder:

private void initialize() {
    camera.unlock();

    recorder.setCamera(camera);
    recorder.setAudioSource(MediaRecorder.AudioSource.CAMCORDER);
    recorder.setVideoSource(MediaRecorder.VideoSource.CAMERA);
    recorder.setOutputFormat(MediaRecorder.OutputFormat.MPEG_4);
    recorder.setAudioEncoder(MediaRecorder.AudioEncoder.AAC);
    recorder.setVideoEncoder(MediaRecorder.VideoEncoder.H264);
    recorder.setVideoFrameRate(20);
    recorder.setOutputFile(filePath);

    try {
        recorder.prepare();
    } catch (IllegalStateException e) {
        e.printStackTrace();
        finish();
    } catch (IOException e) {
        e.printStackTrace();
        finish();
    }
}

It's important to note, that camera.unlock() has to be called BEFORE the whole initialization process of the media recorder. That said also be aware of the proper order of each set property, otherwise you'll get an IllegalStateException when calling prepare() or start(). When it comes to recording, i do this. This will usually be triggered by a view element:

public void record(View view) {
    if (recording) {
        recorder.stop();

        //TODO: do stuff....

        recording = false;
    } else {
        recording = true;

        initialize();
        recorder.start();
    }
}

So now, i finally can record properly. But what's with that flash? Last but not least, here comes the magic behind the scenes:

public void flash(View view) {
    if(!recording) {
        camera.lock();
    }

    parameters.setFlashMode(parameters.getFlashMode().equals(Parameters.FLASH_MODE_TORCH) ? Parameters.FLASH_MODE_OFF : Parameters.FLASH_MODE_TORCH);
    camera.setParameters(parameters);

    if(!recording) {
        camera.unlock();
    }
}

Everytime i call that method via an onClick action i can change the flash mode, even during recording. Just take care of properly locking the camera. Once the lock is aquired by the media recorder during recording, you don't have to lock/unlock the camera again. It doesn't even work. This was tested on a Samsung Galaxy S3 with Android-Version 4.1.2. Hope this approach helps.

Answer 2

To access the device camera, you must declare the CAMERA permission in your Android Manifest. Also be sure to include the <uses-feature> manifest element to declare camera features used by your application. For example, if you use the camera and auto-focus feature, your Manifest should include the following:

 <uses-permission android:name="android.permission.CAMERA" />
 <uses-feature android:name="android.hardware.camera" />
 <uses-feature android:name="android.hardware.camera.autofocus" />

A sample that checks for torch support might look something like this:

//Create camera and parameter objects
private Camera mCamera;
private Camera.Parameters mParameters;
private boolean mbTorchEnabled = false;

//... later in a click handler or other location, assuming that the mCamera object has already been instantiated with Camera.open()
mParameters = mCamera.getParameters();

//Get supported flash modes
List flashModes = mParameters.getSupportedFlashModes ();

//Make sure that torch mode is supported
//EDIT - wrong and dangerous to check for torch support this way
//if(flashModes != null && flashModes.contains("torch")){
if(flashModes != null && flashModes.contains(Camera.Parameters.FLASH_MODE_TORCH)){
    if(mbTorchEnabled){
        //Set the flash parameter to off
        mParameters.setFlashMode(Camera.Parameters.FLASH_MODE_OFF);
    }
    else{
        //Set the flash parameter to use the torch
        mParameters.setFlashMode(Camera.Parameters.FLASH_MODE_TORCH);
    }

    //Commit the camera parameters
    mCamera.setParameters(mParameters);

    mbTorchEnabled = !mbTorchEnabled;
}

To turn the torch on, you simply set the camera parameter Camera.Parameters.FLASH_MODE_TORCH

Camera mCamera;
Camera.Parameters mParameters;

//Get a reference to the camera/parameters
mCamera = Camera.open();
mParameters = mCamera.getParameters();

//Set the torch parameter
mParameters.setFlashMode(Camera.Parameters.FLASH_MODE_TORCH);

//Comit camera parameters
mCamera.setParameters(mParameters);

To turn the torch off, set Camera.Parameters.FLASH_MODE_OFF

Answer 3

Try this.. hopefully it will work.. :)

 private static Torch torch;

          public Torch() {
            super();
            torch = this;
          }

          public static Torch getTorch() {
            return torch;
          }

          private void getCamera() {
            if (mCamera == null) {
              try {
                mCamera = Camera.open();
              } catch (RuntimeException e) {
                Log.e(TAG, "Camera.open() failed: " + e.getMessage());
              }
            }
          }
        public void toggleLight(View view) {
            toggleLight();
          }

          private void toggleLight() {
            if (lightOn) {
              turnLightOff();
            } else {
              turnLightOn();
            }
          }

          private void turnLightOn() {
            if (!eulaAgreed) {
              return;
            }
            if (mCamera == null) {
              Toast.makeText(this, "Camera not found", Toast.LENGTH_LONG);
                   button.setBackgroundColor(COLOR_WHITE);
              return;
            }
            lightOn = true;
            Parameters parameters = mCamera.getParameters();
            if (parameters == null) {
                    button.setBackgroundColor(COLOR_WHITE);
              return;
         }
            List<String> flashModes = parameters.getSupportedFlashModes();
               if (flashModes == null) {
                   button.setBackgroundColor(COLOR_WHITE);
              return;
            }
            String flashMode = parameters.getFlashMode();
            Log.i(TAG, "Flash mode: " + flashMode);
            Log.i(TAG, "Flash modes: " + flashModes);
            if (!Parameters.FLASH_MODE_TORCH.equals(flashMode)) {
                   if (flashModes.contains(Parameters.FLASH_MODE_TORCH)) {
                parameters.setFlashMode(Parameters.FLASH_MODE_TORCH);
                mCamera.setParameters(parameters);
                button.setBackgroundColor(COLOR_LIGHT);
                startWakeLock();
              } else {
                Toast.makeText(this, "Flash mode (torch) not supported",
                    Toast.LENGTH_LONG);
                       button.setBackgroundColor(COLOR_WHITE);
                Log.e(TAG, "FLASH_MODE_TORCH not supported");
              }
            }
          }
         private void turnLightOff() {
            if (lightOn) {
                    button.setBackgroundColor(COLOR_DARK);
              lightOn = false;
              if (mCamera == null) {
                return;
              }
              Parameters parameters = mCamera.getParameters();
              if (parameters == null) {
                return;
              }
              List<String> flashModes = parameters.getSupportedFlashModes();
              String flashMode = parameters.getFlashMode();
                   if (flashModes == null) {
                return;
              }
              Log.i(TAG, "Flash mode: " + flashMode);
              Log.i(TAG, "Flash modes: " + flashModes);
              if (!Parameters.FLASH_MODE_OFF.equals(flashMode)) {
                       if (flashModes.contains(Parameters.FLASH_MODE_OFF)) {
                  parameters.setFlashMode(Parameters.FLASH_MODE_OFF);
                  mCamera.setParameters(parameters);
                  stopWakeLock();
                } else {
                  Log.e(TAG, "FLASH_MODE_OFF not supported");
                }
              }
            }
          }
     private void startPreview() {
        if (!previewOn && mCamera != null) {
          mCamera.startPreview();
          previewOn = true;
        }
      }

      private void stopPreview() {
        if (previewOn && mCamera != null) {
          mCamera.stopPreview();
          previewOn = false;
        }
      }

      private void startWakeLock() {
        if (wakeLock == null) {
          Log.d(TAG, "wakeLock is null, getting a new WakeLock");
          PowerManager pm = (PowerManager) getSystemService(Context.POWER_SERVICE);
          Log.d(TAG, "PowerManager acquired");
          wakeLock = pm.newWakeLock(PowerManager.PARTIAL_WAKE_LOCK, WAKE_LOCK_TAG);
          Log.d(TAG, "WakeLock set");
        }
        wakeLock.acquire();
        Log.d(TAG, "WakeLock acquired");
      }

      private void stopWakeLock() {
        if (wakeLock != null) {
          wakeLock.release();
          Log.d(TAG, "WakeLock released");
        }
      }
     @Override
      public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        if (Eula.show(this)) {
          eulaAgreed = true;
        }
        setContentView(R.layout.main);
        button = findViewById(R.id.button);
        surfaceView = (SurfaceView) this.findViewById(R.id.surfaceview);
        surfaceHolder = surfaceView.getHolder();
        surfaceHolder.addCallback(this);
        surfaceHolder.setType(SurfaceHolder.SURFACE_TYPE_PUSH_BUFFERS);
        disablePhoneSleep();
        Log.i(TAG, "onCreate");
      }

Answer 4

After preparing media recorder, use camera.lock(), and then set whatever parameters you want to set to camera. But before starting recording you need to call camera.unlock(), and after you stop media recorder you need to call camera.lock() to start preview. Enjoy!!!