src/main/java/org/jcodec/codecs/h264/decode/BlockInterpolator.java
private static void getChroma0X(byte[] pels, int picW, int picH, byte[] blk, int blkOff, int blkStride, int fullX,
            int fullY, int fracY, int blkW, int blkH) {
        int w00 = fullY * picW + fullX;
        int w01 = w00 + (fullY < picH - 1 ? picW : 0);
        int eMy = 8 - fracY;

        for (int j = 0; j < blkH; j++) {
            for (int i = 0; i < blkW; i++) {

                blk[blkOff + i] = (byte) ((eMy * pels[w00 + i] + fracY * pels[w01 + i] + 4) >> 3);
            }
            w00 += picW;
            w01 += picW;
            blkOff += blkStride;
        }
    }
private static void getChroma0X(byte[] pels, int picW, int picH, byte[] blk, int blkOff, int blkStride, int fullX,
            int fullY, int fracY, int blkW, int blkH) {
        int w00 = fullY * picW + fullX;
        int w01 = w00 + (fullY < picH - 1 ? picW : 0);
        int eMy = 8 - fracY;

        for (int j = 0; j < blkH; j++) {
            for (int i = 0; i < blkW; i++) {

                blk[blkOff + i] = (byte) ((eMy * pels[w00 + i] + fracY * pels[w01 + i] + 4) >> 3);
            }
            w00 += picW;
            w01 += picW;
            blkOff += blkStride;
        }
    }
Chroma (X,0)