Method of coding video signals and transmission system thereof

Claim 3

The method according to claim 1; further comprising dividing each said frame of video data into a plurality of sub-regions thereof, allocating to said frame a main region transmission allowable data quantity, and distributing to each of said sub-regions a portion of said main region transmission allowable data quantity constituting a respective sub-region transmission allowable data quantity corresponding to a digital video signal quantity of the respective sub-region; and in which said size of the quantizing step for each of said sub-regions is controlled on the basis of the respective sub-region transmission allowable data quantity.

Claim 4

The method according to claim 2; in which said sub-region transmission allowable data quantity for each of said sub-regions is determined on the basis of a ratio of the digital video signal quantity of the respective sub-region to the digital video signal quantity of said main region.

Claim 5

The method according to claim 3; in which said size of the quantizing step is further controlled to maintain constant the amount of data generated from said plurality of sub-regions making up each said main region.

Claim 6

The method according to claim 1; in which said controlling of the size of said quantizing step includes accumulating a first total absolute value of said frame of video data, dividing said frame of video data into a plurality of sub-regions thereof, accumulating a second total absolute value of each said sub-region of video data, distributing a total bit amount allowed for transmission of said first total absolute value to a bit amount allowed for transmission of each said sub-region in proportion to said second total absoslute value, and determining said size of the quantization step in response to said bit amount allowed for transmission of the respective sub-region.

Claim 7

The method according to claim 5; in which said first total absolute value is obtained from a present frame which is to be transmitted.

Claim 8

The method according to claim 5; in which said first total absoslute value is obtained from a frame preceding a frame which is to be transmitted.

Claim 9

The method according to claim 1; in which said variable length code is transmitted through a transmission buffer memory; and further comprising controlling said size of the quantizing step in accordance with a quantity of data remaining in said memory so as to avoid overflowing and under flowing of the latter.

Claim 10

The method according to claim 1; in which said controlling of the size of said quantizing step includes accumulating a total absolute value of said frame of video data, dividing said frame of video data into a plurality of sub-regions thereof, determining a total bit amount allowed for transmission of said total absolute value, and determining said size of the quantizing step as a product of a proportional coefficient and a ratio of said total absolute value and said total bit amount allowed for transmission thereof.

Claim 11

The method according to claim 9; further comprising updating said proportional coefficient at least from frame-to-frame.

Claim 12

The method according to claim 1; further comprising dividing each said frame of video data into a plurality of sub-regions each containing a predetermined number of pixels and corresponding to a transmission unit block, accumulating a total absolute value of transmission data for each said transmission unit block, and determining from said total absolute value of transmission data a mean value thereof for each said pixel; and in which said size of the quantizing step is further controlled on the basis of said mean value.

Claim 13

The method according to claim 11; further comsprising transmitting said variable length code through a transmission buffer memory having a predetermined buffer capacity, determining the remaining quantity of said buffer capacity, calculating a size of the quantizing step from a product of said mean value of transmission data and a ratio of said remaining quantity to said buffer capacity, and substituting predetermined minimum and maximum values of said quantizing step in the event that the calculated size of the quantizing step is below or above, respectively, said minimum and maximum values.

Claim 14

The method according to claim 1; further comprising transmitting said variable length code through a transmission buffer memory having a predetermined buffer capacity, determining the quantity of said buffer capacity remaining in said buffer memory, and detecting motion in a picture from successive frames of said video data; and in which said controlling of the size of said quantizing step is in accordance with said motion in a picture that is detected and with said remaining quantity of said buffer capacity.

Claim 15

The method according to claim 13; further comprising dividing each said frame of video data into a plurality of sub-regions each containing a predetermined number of pixels of data to be coded, generating a feedback quantization step on the basis of said remaining quantity of buffer capacity, and comparing said data of each of said pixels with said feedback quantization step for said detecting of motion in a picture.

Claim 16

The method according to claim 14; in which, when said comparing of said data of each pixel with said feedback quantization step indicates the presence of motion, said controlling of the size of said quantizing step for a sub-region being coded is effected on the basis of comparing data in successive frame from sub-regions which are adjacent the coded sub-region.

Claim 17

The method according to claim 15; in which said adjacent sub-regions are respectively differently displaced horizontally and vertically in respect to said coded sub-region; and in which, in comparing data in successive frames from said differently displaced sub-regions, the results thereof have differently weighted values in said controlling of said size of the quantizing step.

Claim 18

The method according to claim 16; in which said controlling of the size of said quantizing step further includes adding said differently weighted values of the results to provide a sum of said values, detecting motion in said coded sub-region, determining a feedback quantization step transform ratio on the basis of the detection of motion in said coded sub-region and said sum of the differently weighted values, and obtaining said surrounding said one sub-region to be coded, determining a maximum difference between said mean value associated with said sub-region to be coded and said mean values associated with said surrounding sub-regions, selecting a feedback quantization step transform ratio in accordance with the amount of said maximum difference, and calculating said size of the quantizing step from said feedback quantization step and said feedback quantization step transform ratio.

Claim 19

The method according to claim 19; further comprising substituting predetermined minimum and maximum values of said quantizing step in the event that the calculated size of the quantizing step is below or above, respectively, said minimum and maximum values.

Claim 20

The method according to claim 1; further comprising dividing each said frame of video data into a plurality of blocks, generating predictive data for each of said blocks, providing deviation data as the difference between the video data and predictive data for each of said blocks, accumulating a first total absolute value of said deviation data for each said frame, dividing said first total absolute value by the number of said blocks in a frame so as to obtain a mean value of the absolute value of said deviation data for each said block, setting a threshold level in accordance with said mean value, calculating a second total absolute value of said deviation data for each of said blocks, determining whether or not said second total absolute value is greater than said threshold level, applying to said discrete cosine transform coded data a weighting coefficient having a gradient when said second total absolute value is greater than said threshold level, and applying to said discrete cosine transform coded data a flat weighting coefficient when said second total absolute value is less than said threshold value.