Method and apparatus of current picture referencing for video coding using adaptive motion vector resolution and sub-block prediction mode

An apparatus of syntax processing for a video encoding system and video decoding system, wherein current picture referencing (CPR) and adaptive motion vector resolution (AMVR) coding tools are enabled, the apparatus comprising one or more electronic circuits or processors arrange to:

• determine a current reference picture for a current block in a current picture;
• and
• when the current reference picture is equal to the current picture, infer an integer motion vector flag to be true without signalling the integer motion vector flag in a bitstream at an encoder side or without parsing the integer motion vector flag from the bitstream at a decoder side for the current block, wherein the integer motion vector flag being true indicates a current motion vector (MV) being represented in one integer number and the integer motion vector flag being false indicates the current motion vector (MV) being represented in one fractional number.

A method of syntax processing by a video encoding system and video decoding system, wherein current picture referencing (CPR) and adaptive motion vector resolution (AMVR) coding tools are enabled, the method comprising:

• determining motion vector differences for a current block in a current picture;
• and
• when all motion vector differences for the current block are equal to zero, inferring an integer motion vector flag to be false without signalling the integer motion vector flag in a bitstream at an encoder side or without parsing the integer motion vector flag from the bitstream at a decoder side for the current block, wherein the integer motion vector flag being true indicates a current motion vector (MV) being represented in one integer number and the integer motion vector flag being false indicates the current motion vector (MV) being represented in one fractional number.

An apparatus of syntax processing for a video encoding system and video decoding system, wherein current picture referencing (CPR) and adaptive motion vector resolution (AMVR) coding tools are enabled, the apparatus comprising one or more electronic circuits or processors arrange to:

• determine motion vector differences for a current block in a current picture;
• and
• when all motion vector differences for the current block are equal to zero, infer an integer motion vector flag to be false without signalling the integer motion vector flag in a bitstream at an encoder side or without parsing the integer motion vector flag from the bitstream at a decoder side for the current block, wherein the integer motion vector flag being true indicates a current motion vector (MV) being represented in one integer number and the integer motion vector flag being false indicates the current motion vector (MV) being represented in one fractional number.