Main.java Source code

Introduction

Here is the source code for Main.java

Source

//package com.java2s;
import android.graphics.Bitmap;

public class Main {
    public static byte[] getNV21(int inputWidth, int inputHeight, Bitmap scaled) {

        int[] argb = new int[inputWidth * inputHeight];
        scaled.getPixels(argb, 0, inputWidth, 0, 0, inputWidth, inputHeight);
        byte[] yuv = new byte[inputWidth * inputHeight * 3 / 2];
        encodeYUV420SP(yuv, argb, inputWidth, inputHeight);
        return yuv;
    }

    public static void encodeYUV420SP(byte[] yuv420sp, int[] argb, int width, int height) {
        final int frameSize = width * height;

        int yIndex = 0;
        int uvIndex = frameSize;

        int a, R, G, B, Y, U, V;
        int index = 0;
        for (int j = 0; j < height; j++) {
            for (int i = 0; i < width; i++) {

                // nuknown why need invert R and B
                a = (argb[index] & 0xff000000) >> 24; // a is not used obviously
                B = (argb[index] & 0xff0000) >> 16;
                G = (argb[index] & 0xff00) >> 8;
                R = (argb[index] & 0xff) >> 0;

                // well known RGB to YUV algorithm
                Y = ((66 * R + 129 * G + 25 * B + 128) >> 8) + 16;
                U = ((-38 * R - 74 * G + 112 * B + 128) >> 8) + 128;
                V = ((112 * R - 94 * G - 18 * B + 128) >> 8) + 128;

                // NV21 has a plane of Y and interleaved planes of VU each
                // sampled by a factor of 2
                // meaning for every 4 Y pixels there are 1 V and 1 U. Note the
                // sampling is every other
                // pixel AND every other scanline.
                yuv420sp[yIndex++] = (byte) ((Y < 0) ? 0 : ((Y > 255) ? 255 : Y));
                if (j % 2 == 0 && index % 2 == 0) {
                    yuv420sp[uvIndex++] = (byte) ((V < 0) ? 0 : ((V > 255) ? 255 : V));
                    yuv420sp[uvIndex++] = (byte) ((U < 0) ? 0 : ((U > 255) ? 255 : U));
                }

                index++;
            }
        }
    }
}