Direct encoding system of composite video signal using inter-frame motion compensation

• US 5,475,430 A
• Filed: 05/17/1994
• Issued: 12/12/1995
• Est. Priority Date: 05/20/1993
• Status: Expired due to Term

• Current Assignee: KDDI Corporation
• Original Assignee: Kokusai Denshi Denwa Company Limited (KDDI Corporation)
• Inventors: Matsumoto, Shuichi, Hamada, Takahiro
• Primary Examiner(s): Britton, Howard W.
• Application Number:
  US08/245,042
• Time in Patent Office: 574 Days
• Field of Search: 348/393, 348/394, 348/395
• US Class Current: 375/240.25
• CPC Class Codes: H04N 11/044 involving transform coding
• CPC Class Codes: H04N 19/619 the transform being operated outside the prediction loop
• CPC Class Codes: H04N 5/145 Movement estimation for video coding H04N19/51

Abstract

Direct encoding of composite video signal which includes both luminance signal (Y) and chrominance signal (C) is carried out without separating luminance signal from chrominance signal. A motion of a block in a frame (8) which provides a motion vector (MV_x, MV_y), and a from a preceding frame is detected in a motion detector reference block is defined in said preceding frame which is locally decoded according to said motion vector. A block to be encoded in a current frame is converted through Hadamard conversion H (1). A composite motion compensation (7) provides a prediction block according to said reference block, which is subject to phase compensation of color sub-carrier, according to remainder of the value MV_x +MV_y when said value is divided by 4assuming that sampling frequency of video signal is four times as high as color sub-carrier frequency. The difference (9) of each element between output matrix of said Hadamard conversion (1) and matrix of said prediction block is quantized (2) and encloded (3). The encoded output is transmitted together with said motion vector. Thus, composite video signal is encoded directly signal, and excellent signal quality with high compression ratio is obtained.

Claims

1. (1) Direct Encoding System of Composite video using inter-frame motion compensation comprising;

an input terminal for receiving a block of input composite video signal which includes both luminance signal (Y) and chrominance signal (C) modulated with color sub-carrier signal, said block being a part of video frame, and having a plurality of pels,

a first Hadamard converter coupled with said input terminal for effecting Hadamard conversion for each block in said input composite video signal,

a subtractor for providing difference between each element of matrix of output of said first Hadamard converter and each related element of matrix of a prediction block,

a quantizer for quantizing output of said subtractor,

a first encoder for encoding output of said quantizer,

an inverse quantizer coupled with output of said quantizer,

an adder coupled with output of said inverse quantizer for providing sum of said output and said prediction block,

a second Hadamard converter coupled with output of said adder for providing inverse Hadamard conversion,

a frame memory coupled with output of said second Hadamard converter to store a frame of locally decoded video signal,

a motion detector coupled with said input terminal through a luminance separation circuit, and output of said frame memory through a luminance separation circuit to provide motion vector (MV_x, MV_y) of each block between a current frame and a preceding frame,

a composite motion compensator having at least a third Hadamard conversion unit, and a phase compensation circuit, coupled with output of said motion detector, and output of said frame memory, to determine a reference block in a preceding frame according to said motion vector (MV_x, MV_y), to carry out Hadamard conversion to said reference block, to effect phase compensation of color sub-carrier of said Hadamard converted reference block, so that the phase compensated reference block is applied to said subtractor as said prediction block,

a second encoder for encoding said motion vector,

a multiplexer for multiplexing outputs of said first encoder and said second encoder, and

an output terminal coupled with output of said multiplexer to provide encoded video signal.

2. Direct encoding system of composite video signal according to claim 1, wherein said phase compensation circuit is coupled with output of said third Hadamard conversion unit, and has means for exchanging and inversing sign of lines of matrix of an Hadamard converted reference block.

3. Direct encoding system of composite video signal according to claim 1, wherein a first switch (SW1) is provided for switching input of said quantizer between output of said subtractor and output of said first Hadamard conversion unit and a second switch (SW2) is provided for switching input of said adder between output of said composite motion compensator and a null point so that input of said quantizer is switched to output of said subtractor and input of said adder is coupled with output of said composite motion compensator only when sum of absolute value of each element of matrix of a block to be encoded of output of said subtractor is equal to or smaller than that of output of said first Hadamard conversion unit.

4. Direct encoding system of composite video signal according to claim 1, wherein phase compensation of a reference block is carried out only for a part of elements of Hadamard converted reference block.

5. Direct encoding system of composite video signal according to claim 1, wherein said composite motion compensator has further an interpolator, and a prediction block decision circuit, and is further coupled with output of said first Hadamard conversion unit, said composite motion compensator takes a plurality of candidate reference blocks which are located adjacent with each other in a frame memory, effects phase compensation for each candidate reference block, effects interpolation for providing reference blocks with fraction precision by said candidate reference blocks, and said prediction block decision circuit selects a prediction block from said reference blocks with fraction precision so that sum of absolute value of each elements of the difference of the matrices between a block to be encoded and each reference block is the minimum.

6. Direct encoding system of composite video signal according to claim 3, wherein said block has 8×

8 pels, each of Hadamard conversion unit is 8 order Hadamard converter, number of candidate reference blocks is 9, and number of interpolated reference blocks is 15.