Device and method for performing half-pixel accuracy fast search in video coding

An apparatus for obtaining a motion vector between a first and a second frame of video image data having sub-pixel accuracy comprising:

• a memory having a program and a processor, the program configured, when executed, to perform:
• identifying a first conjugate sub-pixel value in a first direction having a lowest first direction MAD value;
• identifying a second conjugate sub-pixel value in a second direction having a lowest second direction MAD value;
• and
• determining a motion vector representing the distance between the first macroblock and the second macroblock using the integer pixel location and a sub-integer pixel location, wherein the sub-pixel location is obtained from the first conjugate sub-pixel value and the second conjugate sub-pixel value having the lowest MAD value.

A computer program comprising:

• a computer-usable medium having program components embodied therein, when executed by a processor, for obtaining a motion vector having half-pixel accuracy between a first and a second frame of video image data, the computer usable medium comprising:
• at an integer pixel location having a lowest mean of absolute difference (“MAD”) value in the second frame relative to the first frame,
• a component of the program configured to identify a first conjugate sub-pixel value in a first direction having a lowest first direction MAD value;
• a component of the program configured to identify a second conjugate sub-pixel value in a second direction having a lowest second direction MAD value;
• and
• a component of the program configured to determine a motion vector representing the distance between the first macroblock and the second macroblock using the integer pixel location and a sub-integer pixel location, wherein the sub-pixel location is obtained from the first conjugate sub-pixel value and the second conjugate sub-pixel value having the lowest MAD value.

A device for obtaining a motion vector between a first macroblock contained in a first frame and a second macroblock contained in a second frame of video image data comprising:

• a memory device that stores executable program codes;
• a processor that accesses the memory device and executes the instructions contained therein, the processor comprising:
• a component configured to identify a first conjugate sub-pixel value in a first direction having a lowest first direction MAD value;
• a component configured to identify a second conjugate sub-pixel value in a second direction having a lowest second direction MAD value;
• and
• a component configured to determine a motion vector representing the distance between the first macroblock and the second macroblock using the integer pixel location and a sub-integer pixel location, wherein the sub-pixel location is obtained from the first conjugate sub-pixel value and the second conjugate sub-pixel value having the lowest MAD value.

A fast search sub-pixel accuracy method for obtaining a motion vector between successive frames of video image data, the method comprising the steps of:

• determining a first macroblock of a first frame comprising a plurality of pixels arranged in a two-dimensional array;
• selecting a second macroblock of a second frame comprising a plurality of pixels arranged in a two-dimensional array having the lowest mean of absolute differences (MAD) value between the first and the second macroblocks;
• determining a minimum pixel location having the lowest MAD value in the second macroblock;
• calculating conjugate sub-pixel values in a first direction centered on the minimum pixel location;
• determining the conjugate sub-pixel value in the first direction having the lowest MAD value;
• calculating conjugate sub-pixel values in a second direction centered on the sub-pixel having the lowest MAD value in the first direction;
• determining the conjugate sub-pixel value in the second direction having the lowest MAD value;
• and
• determining a motion vector for the macroblock representing the distance between the first macroblock and the second macroblock using the integer pixel location and the sub integer pixel location having the lowest MAD values.

A method of obtaining a motion vector between a first macroblock contained in a first frame and a second macroblock contained in a second frame of video image data comprising:

• at an integer pixel location having a lowest mean of absolute difference (“MAD”) value in the second frame relative to the first frame, determining a first sub-pixel value in a first direction having a lowest first direction MAD value;
• determining a second sub-pixel value in a second direction centered on the first sub-pixel value, the second sub-pixel value having a lowest second direction MAD value;
• and
• determining a motion vector representing the distance between the first macroblock and the second macroblock using the integer pixel location and the second sub-integer pixel location.

A method of obtaining a motion vector between a first macroblock contained in a first frame and a second macroblock contained in a second frame of video image data comprising:

• at an integer pixel location having a lowest mean of absolute difference (“MAD”) value in the second frame relative to the first frame, determining a first sub-pixel value in a first diagonal direction having a lowest first direction MAD value;
• determining a second sub-pixel value in a second diagonal direction centered on the first sub-pixel value, the second sub-pixel value having a lowest second direction MAD value;
• and
• determining a motion vector representing the distance between the first macroblock and the second macroblock using the integer pixel location and the second sub-integer pixel location.

A method of obtaining a motion vector between a first macroblock contained in a first frame and a second macroblock contained in a second frame of video image data in a video recorder, the method comprising:

• at an integer pixel location having a lowest mean of absolute difference (“MAD”) value in the second frame relative to the first frame, determining a first sub-pixel value in a first direction having a lowest first direction MAD value;
• determining a second sub-pixel value in a second direction centered on the first sub-pixel value, the second sub-pixel value having a lowest second direction MAD value;
• determining a motion vector representing the distance between the first macroblock and the second macroblock using the integer pixel location and the second sub-integer pixel location;
• and
• storing the motion vector on a storage device.