Variable length coding method using different bit assigning schemes for luminance and chrominance signals
AssigneeMitsubishi Denki Kabushiki Kaisha
InventorsYukari Arano, Ken Onishi
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Abstract
A variable length coding method designed to assign a different number of coding bits in accordance with the information content a sample holds when an analog signal such as a television signal or the like is converted to a digital signal. An assigning method of coding bits used to a luminance signal is different from that used to a chrominance signal. A variable length coding method is further capable of selecting an optimum assigning method in accordance with contents of an original signal from a plurality of determined assigning methods of coding bits. The data related to the plurality of assigning methods of coding bits is recorded on a medium after it is added to a coded digital signal.
Claims16
A variable length coding method for coding an analog signal containing a first analog signal and a second analog signal, whose frequency components are different, to a digital signal, comprising the steps of:
- (a) obtaining a first block having a predetermined number of sample signals and a first length in a horizontal direction, by sampling said first analog signal at a first sampling frequency;
- (b) obtaining a second block having the predetermined number of sample signals and a second length in the horizontal direction, larger than said first length, by sampling said second analog signal at a second sampling frequency;
- (c) coding said first block using a first bit map table;
- and
- (d) coding said second block using a second bit map table, different from said first bit map table, wherein a greater number of bits are assigned to said second block as a result of said second length.
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) obtaining a first sub-block having a predetermined number of sample signals and a first length in a horizontal direction, by sampling said luminance signal at a predetermined sampling frequency;
- (b) obtaining two second sub-blocks each of which has said predetermined number of sample signals and a second length in the horizontal direction, larger than said first length, by sampling said two kinds of chrominance signal at half of said predetermined sampling frequency;
- (c) composing a macro-block by combining said first sub-block and two second sub-blocks;
- (d) coding said first sub-block using a first bit map table;
- and
- (f) coding said second sub-blocks using a second bit map table, different from said first bit map table, wherein a greater number of bits are assigned to said second sub-block as a result of said second length.
A variable length coding method for coding an analog signal to a digital signal, comprising the steps of:
- (a) obtaining a block having a predetermined number of sample signals by sampling said analog signal at a predetermined sampling frequency;
- (b) performing a discrete cosine transform (DCT) for said block and obtaining coefficients;
- (c) scanning said coefficients in a predetermined order and obtaining a value R indicating a number of consecutive zero coefficients and a value S indicating an absolute value of each coefficient;
- (d) computing an existing probability of the combination of said R and S;
- (e) determining a number of coding bits to be assigned to each combination of said R and S based on the existing probability;
- and
- (f) coding each coefficient according to the determined number of coding bits.
A variable length coding method for coding a television signal, containing a luminance signal having a first length in a horizontal direction and two kinds of chrominance signal having a second length in the horizontal direction, larger than the first length, to a digital signal, comprising the steps of:
- (a) obtaining a digital signal in every field by sampling said television signal per field at a predetermined sampling frequency;
- (b) dividing said digital signal in every field into a plurality of blocks;
- (c) coding a digital signal equivalent for said luminance signal using a first bit map table;
- and
- (d) coding a digital signal equivalent for said chrominance signal using a second bit map table, different from said first bit map table, wherein a greater number of bits are assigned to said two kinds of chominance signal as a result of said second length.
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 from each other, to a digital signal of variable length and recording medium, comprising:
- (a) obtaining a first block having a predetermined number of sample signals and a first length in a horizontal direction, by sampling said first analog signal at a first sampling frequency;
- (b) obtaining a second block having the predetermined number of sample signals and a second length in the horizontal direction, larger than said first length, by sampling said second analog signal at a second sampling frequency;
- (c) coding said first block using a first bit map table;
- (d) coding said second block using a second bit map table, different from said first bit map table, wherein a greater number of bits are assigned to said second block as a result of said second length;
- and
- (e) recording data related to said first bit map table and said second bit map table on said recording medium.
A variable length coding and recording method for coding a television signal containing a luminance signal having a first length in a horizontal direction and two kinds of chrominance signal having a second length in the horizontal direction, larger than the first length, to a digital signal of variable length and recording the coded digital signal on a tape for a digital video cassette recorder, comprising:
- (a) obtaining a first sub-block having a predetermined number of sample signals by sampling said luminance signal at a predetermined sampling frequency;
- (b) 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;
- (c) coding said first sub-block using a first bit map table;
- (d) coding said second sub-blocks using a second bit map table, different from said first bit map table, wherein a greater number of bits are assigned to said second sub-block as a result of said second length;
- and
- (e) recording data related to said first bit map table and said second bit map table on said tape.
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 of variable length and recording the coded digital signal on a tape for a digital video cassette recorder, comprising:
- (a) obtaining blocks having a predetermined number of sample signals by sampling said luminance signal and chrominance signal respectively at a predetermined sampling frequency;
- (b) performing a discrete cosine transform (DCT) for said each block and obtaining coefficients;
- (c) scanning said coefficients in a predetermined order and obtaining a value R indicating a number of consecutive zero coefficients and a value S indicating an absolute value of each coefficient;
- (d) computing an existing probability of the combination of said R and S;
- (e) forming a bit map indicating a number of coding bits to be assigned in each combination of said R and S based on the existing probability;
- (f) coding each coefficient according to said bit map;
- and
- (g) recording on said tape, data related to said bit map in addition to data obtained by coding each coefficient.
Dependencies are inferred from the claim text.