Video compression system
A improvement to video compression techniques is described in which blocks of video input information are compared in their respective pixel values to corresponding blocks of immediately preceding frames. The blocks are analyzed to determine whether change has occurred in accordance with two tests. First, the pixel values of the block are compared to the pixel values of a preceding block and if a threshold number of pixel values in the block exceed their counterparts by a threshold amount, then the block is assumed to have changed and is communicated via a standard communication protocol, compression technique and media. Second, even if the threshold number of pixels in the block has not changed, the pixel values are compared with their prior frame counterparts to determine if any one pixel value has changed in magnitude more than a second threshold amount. Again, one such pixel is identified, then the block is assumed to have changed and is communicated.
1. A computer-implemented method in a data processing system for communicating video information as the video information changes from one frame to another, comprising:
a. determining changes in pixel values within a current block of a frame of the video information;
b. testing:
(i) whether a change in pixel value determined in step (a) for any one of the pixels in the current block exceeds an override threshold, and
(ii) whether a plural number of pixels in the current block that changed in pixel value by at least a noise threshold is equal to or greater than a block change threshold; and
c. if the test of either step b.i. or step b.ii. is true, then communicating information identifying the pixel values within the block;
d. if both conditions of steps b.i. and b.ii. are not true, then communicating a no change condition in the current block comprising communicating nothing regarding the current block; and
decoding the video information by writing current blocks for which nothing is communicated as unchanged compared to a corresponding block in a previous frame.
2. The method according to claim 1 , wherein said block change threshold is equal to the number of pixels in the current block.
3. The method according to claim 1 , wherein said noise threshold is greater than one.
4. The method according to claim 1 , wherein the step of transmitting comprises transmitting the information identifying the pixel values within the block to a compressor for compression prior to transmission over a communication channel.
5. A video encoder comprising:
a pixel value analyzer analyzing pixel values within a current block of a frame of video information to determine changes in pixel values between frames;
a comparator testing:
(i) whether a change in pixel value determined by the pixel value analyzer for any one of the pixels in the current block exceeds a override threshold, and
(ii) whether a plural number of pixels in the current block that changed in pixel value by at least a noise threshold is equal to or greater than a block change threshold, and
a transmitter transmitting information identifying the pixel values within the block if the comparator determines either condition (i) or condition (ii) is true, and if the comparator determines both conditions (i) and (ii) are not true, then communicating a no change condition in the current block comprising communicating nothing regarding the current block.
6. The video encoder according to claim 5 , wherein said block change threshold is equal to the number of pixels in the current block.
7. The video encoder according to claim 5 , wherein said noise threshold is greater than one.
8. The video encoder according to claim 5 , wherein the transmitter further comprises a compressor for compressing the pixel values within the block prior to transmission over a communication channel.