CODEWITHSUNDEEP
androidandroid-camera
Vlad Ilie
Vlad Ilie

Reputation: 1409

How fast can an Android camera flash turn on/off?

I want to turn the LED flash for the camera of an Android smartphone very fast on/off, and I was wondering if anyone knows about hardware/OS limitation specifications?

The flash light software I've used so far on my Samsung GT s7580 seemed to have pretty big latency when I tried to switch on and off, and the application I want to make needs to keep the light open for a 10th of a second...

Am I barking up the wrong tree?

Upvotes: 4

Views: 2864

Answers (2)

Red wine
Red wine

Reputation: 172

I was wondering the same thing, and I got a time that varied between about 2.5 and 3 seconds for 50 on/off cycles in a Samsung Galaxy Ace 3 GT-S7275Y I used the deprecated Camera object and the code I used is pasted below:

Camera cam;
Camera.Parameters p;


public void turnOnFlashLight() {
    if (cam != null) {
        p.setFlashMode(Camera.Parameters.FLASH_MODE_TORCH);
        cam.setParameters(p);
    }

}

public void turnOffFlashLight() {
    if (cam != null) {
        p.setFlashMode(Camera.Parameters.FLASH_MODE_OFF);
        cam.setParameters(p);
    }
}

public void prepareCamera() {
    if (cam == null) {
        try {
            cam = Camera.open();
            p = cam.getParameters();
            if (getPackageManager().hasSystemFeature(PackageManager.FEATURE_CAMERA_FLASH)) {
                p.setFlashMode(Camera.Parameters.FLASH_MODE_OFF);
                cam.setParameters(p);
                cam.startPreview();
            }
        } catch (Exception e) {
            e.printStackTrace();
            Toast.makeText(getBaseContext(), "Exception throws in turning on flashlight.", Toast.LENGTH_SHORT).show();
        }
    }
}

public void flashSpeedTest(View v) {
    prepareCamera();
    long startTm = System.nanoTime();
    for (int x = 0; x < 100; ++x) {
        if (x % 2 == 0)
            turnOnFlashLight();
        else
            turnOffFlashLight();
    }
    long elapsed = System.nanoTime() - startTm;
    Misc.showMessage(this, String.format("%.3f seconds", elapsed/1e9));
}

Upvotes: 4

kamituel
kamituel

Reputation: 35950

I just tested LED Strobe app from the Google play, and at its fastest setting it's giving me a pretty rapid on/off cycle. I'd say it's close to 10 fps. Some flashes are bright, some are dimmer (but still visible) - it could be related to the power inefficiencies for such a fast cycle.

Anyway, I don't think you can guarantee 10 fps, it'd be dependent on any of the: phone model, LED module, power connection to the LED, battery power level. In my case, I tested it on Moto X 1st gen.

Upvotes: 1

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