fix YV12 documentation

    public static final int RGB_565 = 4;

    /**

     * Planar 4:2:0 YCrCb format. This format assumes an horizontal stride of 16

     * pixels for all planes and an implicit vertical stride of the image

     * height's next multiple of two.

     *   y_size = stride * ALIGN(height, 2)

     *   c_size = ALIGN(stride/2, 16) * height

     * Android YUV format:

     *

     * This format is exposed to software decoders and applications.

     *

     * YV12 is a 4:2:0 YCrCb planar format comprised of a WxH Y plane followed

     * by (W/2) x (H/2) Cr and Cb planes.

     *

     * This format assumes

     * - an even width

     * - an even height

     * - a horizontal stride multiple of 16 pixels

     * - a vertical stride equal to the height

     *

     *   y_size = stride * height

     *   c_size = ALIGN(stride/2, 16) * height/2

     *   size = y_size + c_size * 2

     *   cr_offset = y_size

     *   cb_offset = y_size + c_size