A: 1 bit Set to 1 if the Advanced Prediction option, bit 12 in PTYPE defined by H.263 [4] was set to 1 for current picutre header, otherwise 0.

DBQ: 2 bits Differential quantization parameter used to calculate quantizer for the B frame based on quantizer for the P frame, when PB-frames option is used. The value should be the same as DBQUANT defined by H.263 [4]. Set to zero if PB-frames option is not used.

EBIT: 3 bits End bit position specifies number of least significant bits that shall be ignored in the last data byte.

F: 1 bit The flag bit indicates the mode of the payload header. F=0, mode A; F=1, mode B or mode C depending on P bit defined below.

I: 1 bit. Picture coding type, bit 9 in PTYPE defined by H.263[4], "0" is intra-coded, "1" is inter-coded.

P: 1 bit Optional PB-frames mode as defined by the H.263 [4]. "0" implies normal I or P frame, "1" PB-frames. When F=1, P also indicates modes: mode B if P=0, mode C if P=1.

R: 4 bits Reserved, must be set to zero.

S: 1 bit Set to 1 if the Syntax-based Arithmetic Coding option, bit 11 in PTYPE defined by the H.263 [4] was set to 1 for current picture header, otherwise 0.

SRC : 3 bits Source format, bit 6,7 and 8 in PTYPE defined by H.263 [4], specifies the resolution of the current picture. 001 SUB-CIF 128x96 010 QCIF 176x144 011 CIF 352x288 100 4CIF 704x576 101 16CIF 1408x1152

TR: 8 bits Temporal Reference for the P frame as defined by H.263 [4]. Set to zero if the PB-frames option is not used.

TRB: 3 bits Temporal Reference for the B frame as defined by H.263 [4]. Set to zero if PB-frames option is not used.

U: 1 bit Set to 1 if the Unrestricted Motion Vector option, bit 10 in PTYPE defined by H.263 [4] was set to 1 in the current picture header, otherwise 0.