Convert NV21 byte array into bitmap readable format

Question

Hey I'm creating small camera app I have implemented every things but I have one problem which is converting NV21 byte array into jpeg format
I have found many way but all of them even not working or work on some devices
firstly i tried this snippet and it work on Xperia z2 5.2 but on galaxy s4 4.4.4

bitmap = BitmapFactory.decodeByteArray(data, 0, data.length);

also this way works on same device and fail on the other

 int pich = camera.getParameters().getPreviewSize().height;
        int picw = camera.getParameters().getPreviewSize().width;
        int[] pix = new int[picw * pich];
        bitmap.getPixels(pix, 0, picw, 0, 0, picw, pich);
                    //  int R, G, B, Y;
                    for (int y = 0; y < pich; y++) {
                        for (int x = 0; x < picw; x++) {
                            int index = y * picw + x;
                          int R = (pix[index] >> 16) & 0xff; 
                         int G = (pix[index] >> 8) & 0xff;     
                    int B = pix[index] & 0xff;
                   pix[index] = 0xff000000 | (R << 16) | (G << 8) | B;
                        }
                                  }

secondly I tried many solutions to convert decode NV21 first one renderscript code

    public Bitmap convertYUV420_NV21toRGB8888_RenderScript(byte [] data,int W, int H, Fragment fragment) {
    // http://stackoverflow.com/questions/20358803/how-to-use-scriptintrinsicyuvtorgb-converting-byte-yuv-to-byte-rgba
    RenderScript rs;
    ScriptIntrinsicYuvToRGB yuvToRgbIntrinsic;
    rs = RenderScript.create(fragment.getActivity());
    yuvToRgbIntrinsic = ScriptIntrinsicYuvToRGB.create(rs, Element.U8_4(rs)); //Create an intrinsic for converting YUV to RGB.

    Type.Builder yuvType = new Type.Builder(rs, Element.U8(rs)).setX(data.length);
    Allocation in = Allocation.createTyped(rs, yuvType.create(), Allocation.USAGE_SCRIPT); //an Allocation will be populated with empty data when it is first created

    Type.Builder rgbaType = new Type.Builder(rs, Element.RGBA_8888(rs)).setX(W).setY(H);
    Allocation out = Allocation.createTyped(rs, rgbaType.create(), Allocation.USAGE_SCRIPT); //an Allocation will be populated with empty data when it is first created

    in.copyFrom(data);//Populate Allocations with data.

    yuvToRgbIntrinsic.setInput(in); //Set the input yuv allocation, must be U8(RenderScript).
    yuvToRgbIntrinsic.forEach(out); //Launch the appropriate kernels,Convert the image to RGB.


    Bitmap bmpout = Bitmap.createBitmap(W, H, Bitmap.Config.ARGB_8888);
    out.copyTo(bmpout); //Copy data out of Allocation objects.
    return bmpout;

}

and also this code

 void decodeYUV420SP(int[] rgb, byte[] yuv420sp, int width, int height) {

    final int frameSize = width * height;

    for (int j = 0, yp = 0; j < height; j++) {
        int uvp = frameSize + (j >> 1) * width, u = 0, v = 0;

        for (int i = 0; i < width; i++, yp++) {

            int y = (0xff & ((int) yuv420sp[yp])) - 16;

            if (y < 0)

                y = 0;

            if ((i & 1) == 0) {

                v = (0xff & yuv420sp[uvp++]) - 128;

                u = (0xff & yuv420sp[uvp++]) - 128;

            }

            int y1192 = 1192 * y;

            int r = (y1192 + 1634 * v);
            int g = (y1192 - 833 * v - 400 * u);
            int b = (y1192 + 2066 * u);

            if (r < 0)
                r = 0;
            else if (r > 262143)

                r = 262143;
            if (g < 0)
                g = 0;
            else if (g > 262143)

                g = 262143;

            if (b < 0)

                b = 0;

            else if (b > 262143)

                b = 262143;

            rgb[yp] = 0xff000000 | ((r << 6) & 0xff0000) | ((g >> 2) & 0xff00) | ((b >> 10) & 0xff);
        }

    }
}

and finally I tried to save the image on sd card and then reopen it but it also fail

File pictureFile = new File(filename);
            int pich = camera.getParameters().getPreviewSize().height;
            int picw = camera.getParameters().getPreviewSize().width;
            Rect rect = new Rect(0, 0,picw, pich);
            YuvImage img = new YuvImage(data, ImageFormat.NV21, picw, picw, null);

            try {
                FileOutputStream fos = new FileOutputStream(pictureFile);
                img.compressToJpeg(rect, 100, fos);
                fos.write(data);
                fos.close();

and this is the result with last 3 approach I had follow

Solution 1

There are a few ways to save an NV21 frame coming from the camera, the easiest way being converting it to a YuvImage then saving it to a Jpeg file:

FileOutputStream fos = new FileOutputStream(Environment.getExternalStorageDirectory() + "/imagename.jpg");
YuvImage yuvImage = new YuvImage(nv21bytearray, ImageFormat.NV21, width, height, null);
yuvImage.compressToJpeg(new Rect(0, 0, width, height), 100, fos);
fos.close();

Alternatively, you can also convert it to Android Bitmap object and save it as a PNG or other format:

YuvImage yuvImage = new YuvImage(nv21bytearray, ImageFormat.NV21, width, height, null);
ByteArrayOutputStream os = new ByteArrayOutputStream();
yuvImage.compressToJpeg(new Rect(0, 0, width, height), 100, os);
byte[] jpegByteArray = os.toByteArray();
Bitmap bitmap = BitmapFactory.decodeByteArray(jpegByteArray, 0, jpegByteArray.length);
FileOutputStream fos = new FileOutputStream(Environment.getExternalStorageDirectory() + "/imagename.png");
bitmap.compress(Bitmap.CompressFormat.PNG, 100, fos);
fos.close();

Note that the last option does a NV21 -> JPEG -> Bitmap Object -> PNG file process so keep in mind that this is not a very efficient way to save preview images from the camera if you need high performance.

UPDATE: I got tired of how long it takes for this conversion to work so I wrote a library (easyRS) around RenderScript to easily do this in one line of code:

Bitmap outputBitmap = Nv21Image.nv21ToBitmap(rs, nv21ByteArray, width, height);

It is around five times faster than the JPEG process in a 2000x2000 image on a Moto G 2nd.

Solution 2

Your second try (with ScriptIntrinsicYuvToRGB) looks promising. With JellyBean 4.3 (API18) or higher do the following (camera preview format must be NV21):

First, don´t create the rs, the yuvToRgbIntrinsic and the allocations in a method or in a loop where the script will be executed. This will slow down your app extremely and may cause out-of-memory errors. Put these in the onCreate().. method:

rs = RenderScript.create(this);  // create rs object only once and use it as long as possible
yuvToRgbIntrinsic = ScriptIntrinsicYuvToRGB.create(rs, Element.U8_4(rs)); // ditto.

With Api18+ the allocations are created much easier (you do not need Type.Builder objects !). With your cameraPreviewWidth and cameraPreviewHeight create allocation aIn:

int yuvDatalength = cameraPreviewWidth*cameraPreviewHeight*3/2; // this is 12 bit per pixel
aIn = Allocation.createSized(rs, Element.U8(rs), yuvDatalength);  

You need a Bitmap for output:

bmpout = Bitmap.createBitmap(cameraPreviewWidth, cameraPreviewHeight, Bitmap.Config.ARGB_8888);

and simply create the aOut allocation from this Bitmap:

aOut = Allocation.createFromBitmap(rs, bmpout);

Set the script´s in-allocation (only once, outside the loop):

yuvToRgbIntrinsic.setInput(aIn); //Set the input yuv allocation, must be U8(RenderScript).

In the "camera loop" do with byte[] data :

aIn.copyFrom(data); // or aIn.copyFromUnchecked(data);  // which is faster and safe with camera data

yuvToRgbIntrinsic.forEach(aOut); //Launch the appropriate kernels,Convert the image to RGB.

aOut.copyTo(bmpout); // copy data from Allocation aOut to Bitmap bmpout

For example, on Nexus 7 (2013, JellyBean 4.3) a full HD (1920x1080 pixel) camera preview conversion takes about 7 ms.

Comments

[Alex Cohn]

If you want to receive Jpeg, please rename your question, it looks as if you want to convert NV21 to RGB, which is a whole different task.

[Alex Cohn]

How did you display the image? Load the Jpeg file into an ImageView?

[user1884872]

Hello! How to get nv21byteArray from Image in OnImageAvailableListener?

[Diego]

how to convert NV21 frame to .mp4 format?

[Rowan Gontier]

With Google play store no longer accepting builds without 64 bit support, I had to abandon the easyRS library- unless I have a wrong setting that prevents 64 bit support.

[Someone Somewhere]

what's cameraPreviewWidth ?

[Abhinav Chauhan]

using that library giving me , installation failed due to null