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US 2002/0054639 A1Published application
Device and method for coding video information
AssigneeKabushiki Kaisha Toshiba
InventorsYuji Kawashima, Atsushi Asano
Life of this patent
Estimating the term…
Abstract
A video encoder includes a signal processing unit for producing block information such as quantization scale and quantized DCT coefficients and a coding unit for variable-length coding the quantized block information. The amount of generated coded data per unit time (Evop) is estimated from the count (Ncoef(i)) of quantized DCT coefficients contained in block information prior to coding, the amount of coded data (C(y)), and the average codeword length (L(y)) of coded block information. A quantization scale control unit determines the most suitable quantization scale factor on the basis of the target amount of generated coded data (Tvop) and the amount of generated coded data (Evop) and sends it to a quantization unit in the signal processing unit.
Claims9
A video coding device comprising:
- setting means for setting a target amount of generated coded data;
- performing means for performing DCT operations on a unit of video information divided into blocks on a block-by-block basis to produce DCT coefficients;
- quantizing means for quantizing the DCT coefficients in accordance with a predetermined quantization scale factor to produce quantized DCT coefficients;
- coding means for variable-length coding the quantized DCT coefficients to produce a bitstream;
- first counter configured to count the number of the quantized DCT coefficients output from the quantization means;
- second counter configured to count the amount of generated coded data in the bitstream output from the coding means;
- computation means for computing an average codeword length of the quantized DCT coefficients from the number of the quantized DCT coefficients from the first counter and the amount of generated coded data from the second counter;
- and
- update means for computing an estimated value of the amount of coded data to be generated for the unit of information, from the average codeword length supplied from the computation means and the number of the quantized DCT coefficients supplied from the first counter, and updating the quantization scale factor in accordance with the target amount of generated coded data and the estimated amount of generated coded data.
6 more elements
A video coding device comprising:
- transform means for performing DCT operations on a unit of video information divided into blocks on a block-by-block basis to produce DCT coefficients;
- quantization means for quantizing the DCT coefficients in accordance with a predetermined quantization scale factor to produce quantized DCT coefficients;
- set means for setting a target number of quantized DCT coefficients for the unit of video information;
- coding means for variable-length coding the quantized DCT coefficients to produce a bitstream;
- first counter configured to count the actual number of quantized DCT coefficients output from the quantization means;
- second counter configured to count the amount of generated coded data in the bitstream output from the coding means;
- average codeword length computation means for computing an average codeword length of the quantized DCT coefficients from the number of the quantized DCT coefficients from the first counter and the amount of generated coded data from the second counter;
- target quantized DCT coefficient computation means for computing the target number of the quantized DCT coefficients that is expected to be counted by the first counter on the basis of the target number of the target quantized DCT coefficients;
- and
- update means for updating the quantization scale factor in accordance with the actual number of the quantized DCT coefficients and the target number of the quantized DCT coefficients and sending the updated quantization scale factor to the quantization means.
7 more elements
A video coding method, comprising steps of:
- setting a target amount of generated coded data;
- performing DCT operations on a unit of video information divided into blocks on a block-by-block basis to produce DCT coefficients;
- quantizing the DCT coefficients in accordance with a predetermined quantization scale factor to produce quantized DCT coefficients;
- variable-length coding the quantized DCT coefficients to produce a bitstream;
- counting the number of the quantized DCT coefficients, Ncoef(i), output by the quantization step;
- counting the amount of generated coded data in the bitstream output by the coding step;
- computing an average codeword length of the quantized DCT coefficients from the number of the quantized DCT coefficients obtained by the first counting step and the amount of generated coded data obtained by the second counting step;
- and
- computing an estimated value for the amount of generated coded data for the unit of information from the average codeword length and the number of the quantized DCT coefficients and updating the quantization scale factor in accordance with the target amount of generated coded data and the estimated amount of generated coded data.
6 more elements
A video coding method comprising the steps of:
- performing DCT operations on a unit of video information divided into blocks on a block-by-block basis to produce DCT coefficients;
- quantizing the DCT coefficients in accordance with a predetermined quantization scale factor to produce quantized DCT coefficients;
- setting a target number of quantized DCT coefficients for the unit of video information;
- variable-length coding the quantized DCT coefficients to produce a bitstream;
- counting the actual number of quantized DCT coefficients output by the quantization step;
- counting the amount of generated coded data in the bitstream output by the coding step;
- computing an average codeword length of the quantized DCT coefficients from the number of the quantized DCT coefficients and the amount of generated coded data;
- computing the target number of the quantized DCT coefficients that is expected to be counted by the first-mentioned counting step on the basis of the target number of quantized DCT coefficients;
- and
- updating the quantization scale factor in accordance with the actual number of the quantized DCT coefficients and the target number of the quantized DCT coefficients and sending the updated quantization scale factor to the quantization step.
7 more elements
Dependencies are inferred from the claim text.