SHIFT_INV_ROW      33 libavcodec/ps2/idct_mmi.c #define SHIFT_INV_ROW   (16 - BITS_INV_ACC)
SHIFT_INV_ROW      50 libavcodec/x86/idct_mmx_xvid.c #define SHIFT_INV_ROW   (16 - BITS_INV_ACC) //11