Variable length coding method

Claim 2

A variable length coding method as set forth in Claim 1, wherein said first analog signal is a video luminance signal and said second analog signal is a video chrominance signal.

Claim 3

A variable length coding method as set forth in Claim 1, wherein said third step includes, a step of executing DCT for said first block and obtaining coefficients; a step of scanning said coefficients in a predetermined order and obtaining R indicating a number of consecutive coefficients with zero and S indicating an absolute value of each coefficient; and a step of coding each coefficient on the basis of the combination of said R and S with said first assigning method of coding bits.

Claim 4

A variable length coding method as set forth in Claim 1, wherein said fourth step includes, a step of executing DCT for said second block and obtaining coefficients; a step of scanning said coefficients in a predetermined order and obtaining R indicating a number of consecutive coefficients with zero and S indicating an absolute value of each coefficient; and a step of coding each coefficient on the basis of the combination of said R and S with said second assigning method of coding bits.

Claim 5

A variable length coding method for coding a television signal containing a luminance signal and two kinds of chrominance signal to a digital signal, comprising: a first step of obtaining a first sub-block having a predetermined number of sample signals by sampling said luminance signal at a predetermined sampling frequency; a second step of obtaining two second sub-blocks each of which has said predetermined number of sample signals by sampling said two kinds of chrominance signal at half of said predetermined sampling frequency; a third step of composing a macro-block by combining said first sub-block and two second sub-blocks; a fourth step of composing one field by combining a plurality of macro-blocks; a fifth step of coding said first sub-block with a first assigning method of coding bits; and a sixth step of coding said second sub-blocks with a second assigning method of coding bits different from said first assigning method.

Claim 6

A variable length coding method as set forth in Claim 5, wherein said first sub-block and said second sub-blocks have sample signals of 8 samples per 1 line × 8 lines.

Claim 7

A variable length coding method as set forth in Claim 5, wherein said fifth step includes, a step of executing DCT for said first sub-block and obtaining coefficients; a step of scanning said coefficients in a predetermined order and obtaining R indicating a number of consecutive coefficients with zero and S indicating an absolute value of each coefficient; and a step of coding each coefficient on the basis of the combination of said R and S with said first assigning method of coding bits.

Claim 8

A variable length coding method as set forth in Claim 5, wherein said sixth step includes, a step of executing DCT for said second sub-blocks and obtaining coefficients; a step of scanning said coefficients in a predetermined order and obtaining R indicating a number of consecutive coefficients with zero and S indicating an absolute value of each coefficient; and a step of coding each coefficient on the basis of the combination of said R and S with said second assigning method of coding bits.

Claim 9

A variable length coding method for coding an analog signal to a digital signal, comprising: a step of determining a plurality of coding methods whose numbers of coding bits are different one another; a step of selecting one coding method from said plurality of coding methods on the basis of the content of said analog signal; and a step of coding said analog signal to said digital signal with the selected coding method.

Claim 10

A variable length coding method for coding an analog signal to a digital signal, comprising: a step of obtaining a block having a predetermined number of sample signals by sampling said analog signal at a predetermined sampling frequency; a step of executing DCT for said block and obtaining coefficients; a step of scanning said coefficients in a predetermined order and obtaining R indicating a number of consecutive coefficients with zero and S indicating an absolute value of each coefficient; a step of computing the existing probability of the combination of said R and S; a step of determining the number of coding bits to be assigned in each combination of said R and S on the basis of the existing probability; and a step of coding each coefficient according to the determined number of coding bits.

Claim 11

A variable length coding method as set forth in Claim 10, wherein the larger said existing probability is, the smaller said number of coding bits to be assigned is.

Claim 12

A variable length coding method as set forth in Claim 10, wherein said analog signal is a luminance signal contained in a television signal.

Claim 13

A variable length coding method as set forth in Claim 10, wherein said analog signal is a chrominance signal contained in a television signal.

Claim 14

A variable length coding method for coding a television signal containing a luminance signal and two kinds of chrominance signal to a digital signal, comprising: a step of obtaining a digital signal in every one field by sampling said television signal per one field at a predetermined sampling frequency; a step of dividing said digital signal in every one field into a plurality of blocks: a step of coding the digital signal equivalent for said luminance signal with a first assigning method of coding bits; and a step of coding the digital signal equivalent for said chrominance signal with a second assigning method of coding bits different from said first assigning method.

Claim 15

A variable length coding and recording method for coding an analog signal to a digital signal in variable length and recording the coded digital signal on a recording medium, comprising: a step of determining a plurality of coding methods whose numbers of coding bits are different one another; a step of selecting one coding method from said plurality of coding methods on the basis of the content of said analog signal; a step of coding said analog signal to said digital signal with the selected coding method; and a step of recording data related to said plurality of coding methods on said recording medium in addition to the coded digital signal.

Claim 16

A variable length coding and recording method as set forth in Claim 15, wherein an error correction code for correcting an error of coding is recorded on said recording medium.

Claim 17

A variable length coding and recording method as set forth in Claim 16, wherein said data related to said plurality of coding methods is superimposed with said error correction code on said recording medium.

Claim 18

A variable length coding and recording method for coding an analog signal containing a first analog signal and a second analog signal whose frequency components are different each other to a digital signal in variable length and recording the coded digital signal on a recording medium, comprising: a step of obtaining a first block having a predetermined number of sample signals by sampling said first analog signal at a first sampling frequency; a step of obtaining a second block having a predetermined number of sample signals by sampling said second analog signal at a second sampling frequency; a step of coding said first block with a first assigning method of coding bits; a step of coding said second block with a second assigning method of coding bits different from said first assigning method; and a step of recording data related to said first and second assigning method on said recording medium.

Claim 19

A variable length coding and recording method for coding a television signal containing a luminance signal and two kinds of chrominance signal to a digital signal in variable length and recording tie coded digital signal on a tape for a digital video cassette recorder, comprising: a step of obtaining a first sub-block having a predetermined number of sample signals by sampling said luminance signal at a predetermined sampling frequency; a step of obtaining two second sub-blocks each of which has said predetermined number of sample signals by sampling said two kinds of chrominance signal at half of said predetermined sampling frequency; a step of coding said first sub-block with a first assigning method of coding bits; a step of coding said second sub-blocks with a second assigning method of coding bits different from said first assigning method; and a step of recording data related to said first and second assigning method on said tape.

Claim 20

A variable length coding and recording method for coding a television signal containing a luminance signal and two kinds of chrominance signal to a digital signal in variable length and recording the coded digital signal on a tape for a digital video cassette recorder, comprising: a step of obtaining blocks having a predetermined number of sample signals by sampling said luminance signal and chrominance signal respectively at a predetermined sampling frequency; a step of executing DCT for said each block and obtaining coefficients; a step of scanning said coefficients in a predetermined order and obtaining R indicating a number of consecutive coefficients with zero and S indicating an absolute value of each coefficient; a step of computing the existing probability of the combination of said R and S; a step of forming a bit map indicating the number of coding bits to be assigned in each combination of said R and S on the basis of the existing probability; a step of coding each coefficient according to said bit map; and a step of recording on said tape data related to said bit map in addition to data obtained by coding each coefficient.