Converting preview frame to bitmap

Question

I know the subject was on the board many times, but i can not get it work anyhow... I want to save view frames from preview to jpeg files. It looks more or less(code is simp

Answer 1

Simply saving to a jpeg is an easier task than converting to bitmap, no need for that YUV decoding code thanks to YuvImage class.

import android.graphics.YuvImage; 

@Override 
public void onPreviewFrame(byte[] data, Camera camera) { 
    try { 
        Camera.Parameters parameters = camera.getParameters(); 
        Size size = parameters.getPreviewSize(); 
        YuvImage image = new YuvImage(data, parameters.getPreviewFormat(), 
                size.width, size.height, null); 
        File file = new File(Environment.getExternalStorageDirectory(), "out.jpg"); 
        FileOutputStream filecon = new FileOutputStream(file); 
        image.compressToJpeg( 
                new Rect(0, 0, image.getWidth(), image.getHeight()), 90, 
                filecon); 
    } catch (FileNotFoundException e) { 
        Toast toast = Toast 
                .makeText(getBaseContext(), e.getMessage(), 1000); 
        toast.show(); 
    } 
} 

Answer 2

In order to avoid degraded JPEG image on the output (e.g. with interleaving green/red spots), you need to flush and close FileOutputStream

FileOutputStream filecon = new FileOutputStream(file); 
image.compressToJpeg( 
            new Rect(0, 0, image.getWidth(), image.getHeight()), 90, 
        filecon);
filecon.flush();
filecon.close();

Answer 3

as I found out the width and height read from PreviewSize were wrong.... In other words the conversion went wrong because it was based on false values. After use a new way of setting the preview settings(from example deleivered by google) everything works fine.

EDIT:

Sorry for the quick answer above and long delay.

It was while ago and I can not dig the code now, but i think that I used:

http://developer.android.com/reference/android/hardware/Camera.Parameters.html#getSupportedPreviewSizes()

and took the first element from the list and set the values with

http://developer.android.com/reference/android/hardware/Camera.Parameters.html#setPreviewSize(int, int)

i stored the width and height and used it to transform picture.

It dont know if it was the best solution, but it worked out.

Answer 4

If I am not mistaken, you want the width and height of the picture to decode, not the width and heigth of the preview.

Answer 5

Alternatively, if you DO need a bitmap for some reason, and/or want to do this without creating a YUVImage and compressing to JPEG, you can use the handy RenderScript 'ScriptIntrinsicYuvToRGB' (API 17+):

@Override 
public void onPreviewFrame(byte[] data, Camera camera) { 
   Bitmap bitmap = Bitmap.createBitmap(r.width(), r.height(), Bitmap.Config.ARGB_8888);
    Allocation bmData = renderScriptNV21ToRGBA8888(
        mContext, r.width(), r.height(), data);
    bmData.copyTo(bitmap);
}

public Allocation renderScriptNV21ToRGBA8888(Context context, int width, int height, byte[] nv21) {
  RenderScript rs = RenderScript.create(context);
  ScriptIntrinsicYuvToRGB yuvToRgbIntrinsic = ScriptIntrinsicYuvToRGB.create(rs, Element.U8_4(rs));

  Type.Builder yuvType = new Type.Builder(rs, Element.U8(rs)).setX(nv21.length);
  Allocation in = Allocation.createTyped(rs, yuvType.create(), Allocation.USAGE_SCRIPT);

  Type.Builder rgbaType = new Type.Builder(rs, Element.RGBA_8888(rs)).setX(width).setY(height);
  Allocation out = Allocation.createTyped(rs, rgbaType.create(), Allocation.USAGE_SCRIPT);

  in.copyFrom(nv21);

  yuvToRgbIntrinsic.setInput(in);
  yuvToRgbIntrinsic.forEach(out);
  return out;
}