gistfile1.java

// decode Y, U, and V values on the YUV 420 buffer described as YCbCr_422_SP by Android  
// David Manpearl 081201  
public void decodeYUV(int[] out, byte[] fg, int width, int height) 
        throws NullPointerException, IllegalArgumentException { 
    int sz = width * height; 
    if (out == null) 
        throw new NullPointerException("buffer out is null"); 
    if (out.length < sz) 
        throw new IllegalArgumentException("buffer out size " + out.length 
                + " < minimum " + sz); 
    if (fg == null) 
        throw new NullPointerException("buffer 'fg' is null"); 
    if (fg.length < sz) 
        throw new IllegalArgumentException("buffer fg size " + fg.length 
                + " < minimum " + sz * 3 / 2); 
    int i, j; 
    int Y, Cr = 0, Cb = 0; 
    for (j = 0; j < height; j++) { 
        int pixPtr = j * width; 
        final int jDiv2 = j >> 1; 
        for (i = 0; i < width; i++) { 
            Y = fg[pixPtr]; 
            if (Y < 0) 
                Y += 255; 
            if ((i & 0x1) != 1) { 
                final int cOff = sz + jDiv2 * width + (i >> 1) * 2; 
                Cb = fg[cOff]; 
                if (Cb < 0) 
                    Cb += 127; 
                else 
                    Cb -= 128; 
                Cr = fg[cOff + 1]; 
                if (Cr < 0) 
                    Cr += 127; 
                else 
                    Cr -= 128; 
            } 
            int R = Y + Cr + (Cr >> 2) + (Cr >> 3) + (Cr >> 5); 
            if (R < 0) 
                R = 0; 
            else if (R > 255) 
                R = 255; 
            int G = Y - (Cb >> 2) + (Cb >> 4) + (Cb >> 5) - (Cr >> 1) 
                    + (Cr >> 3) + (Cr >> 4) + (Cr >> 5); 
            if (G < 0) 
                G = 0; 
            else if (G > 255) 
                G = 255; 
            int B = Y + Cb + (Cb >> 1) + (Cb >> 2) + (Cb >> 6); 
            if (B < 0) 
                B = 0; 
            else if (B > 255) 
                B = 255; 

            out[pixPtr++] = 0xff000000 + (B << 16) + (G << 8) + R; 
        } 
    } 
 
}