Bitrate control method and apparatus for intra-only video sequence coding
AssigneeSamsung Electronics Co., Ltd.
InventorsNak-hoon KIM, Byung-cheol Song, Yun-gu Lee
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Abstract
A bitrate control method and apparatus for video sequence coding by using only intra pictures are provided. The rate control method includes: separating a video sequence formed only with intra pictures, into picture group units, slice units, and macroblock units; and performing bitrate control so that a predetermined amount of bits can be generated when encoding is performed. According to the method and apparatus, overflow and underflow of a buffer can be prevented.
Claims18
A method of controlling a bitrate when a video sequence formed only with intra pictures is encoded, the method comprising:
- dividing the intra pictures into a plurality of picture groups, and determining target bit amounts of the plurality of picture groups;
- dividing intra pictures included in a first picture group into a plurality of slices, and determining target bit amounts of the plurality of slices based on a target bit amount of the first picture group;
- determining a target bit amount of a first macroblock included in a first slice of the plurality of slices based on a target bit amount of the first slice;
- and
- calculating a quantization parameter of a current macroblock to be encoded, by considering the determined target bit amount of the first macroblock, a generated bit amount allocated to a previous macroblock, and buffer fullness.
An apparatus for controlling a bitrate when a video sequence formed only with intra pictures is encoded, the apparatus comprising:
- a buffer that temporarily stores an encoded bitstream;
- a target bit amount determination unit for picture group units that divides the intra pictures into a plurality of picture groups, and determines target bit amounts of the plurality of picture groups;
- a target bit amount determination unit for slice units that divides intra pictures included in a first picture group into a plurality of slices, and determines target bit amounts of the plurality of slices based on a target bit amount of the first picture group;
- a target bit amount determination unit for macroblock units that determines a target bit amount of a first macroblock included in a first slice of the plurality of slices based on the target bit amount of the first slice;
- a bitrate adjustment unit that determines a quantization parameter for encoding a current macroblock, by considering a buffer fullness, the determined target bit amount for the first macroblock unit, and a bit amount generated for a previous macroblock, and by comparing a magnitude of the buffer fullness with a reference value at a time when the current macroblock is encoded, generating a calibration value according to the buffer fullness, and by adding the generated calibration value to the quantization parameter, generating and outputting a calibrated quantization parameter;
- and
- an encoding unit that quantizes the current macroblock based on the calibrated quantization parameter and generates a bitstream.
Dependencies are inferred from the claim text.