US 2020/0404273 A1 · TRANSFORMS FOR LARGE VIDEO AND IMAGE BLOCKS

Abstract

Improved transforms are used to encode and decode large video and image blocks. During encoding, a prediction residual block having a large size (e.g., larger than 32×32) is generated. The pixel values of the prediction residual block are transformed to produce transform coefficients. After determining that the transform coefficients exceed a threshold cardinality representative of a maximum transform block size (e.g., 32×32), a number of the transform coefficients are discarded such that a remaining number of transform coefficients does not exceed the threshold cardinality. A transform block is then generated using the remaining number. During decoding, after determining that the transform coefficients exceed the threshold cardinality, a number of new coefficients are added to the transform coefficients such that a total number of transform coefficients exceeds the threshold cardinality. The transform coefficients are then inverse transformed into a prediction residual block having a large size.

Claims20

Dependent claims

A method for decoding an encoded block, the method comprising:

decoding quantized transform coefficients of the encoded block from a bitstream;
dequantizing the quantized transform coefficients to produce a first number of transform coefficients associated with a transform block having a first size;
determining, based on one or more syntax elements within the bitstream, whether the first number of transform coefficients were encoded using a transform size which exceeds a threshold;
responsive to determining that the first number of transform coefficients were encoded using a transform size which exceeds the threshold, adding one or more zero value coefficients to the first number of transform coefficients to result in a second number of transform coefficients which is greater than the first number of transform coefficients;
inverse transforming the second number of transform coefficients to produce a prediction residual having a second size which is greater than the first size;
reconstructing a video block using the prediction residual and a prediction block for the encoded block;
and
outputting the video block for storage or display.

5 more elements

An apparatus for decoding an encoded block, the apparatus comprising:

a processor configured to execute instructions stored in a non-transitory storage medium to:
decode quantized transform coefficients of the encoded block from a bitstream;
dequantize the quantized transform coefficients to produce a first number of transform coefficients associated with a transform block having a first size;
determine, based on one or more syntax elements within the bitstream, whether the first number of transform coefficients were encoded using a transform size which exceeds a threshold;
responsive to a determination that the first number of transform coefficients were encoded using a transform size which exceeds the threshold:
add one or more zero value coefficients to the first number of transform coefficients to result in a second number of transform coefficients which is greater than the first number of transform coefficients;
and
inverse transform the second number of transform coefficients to produce a first prediction residual having a second size which is greater than the first size;
and
responsive to a determination that the first number of transform coefficients were not encoded using a transform size which exceeds the threshold:
inverse transform the first number of transform coefficients to produce a second prediction residual having the first size;
reconstruct a video block using a prediction block for the encoded block and using the first prediction residual or the second prediction residual;
and
output the video block for storage or display.

11 more elements

A method for decoding an encoded block, the method comprising:

dequantizing quantized transform coefficients of the encoded block to produce a first number of transform coefficients associated with a transform block having a first size;
adding one or more zero value coefficients to the first number of transform coefficients to result in a second number of transform coefficients which is greater than the first number of transform coefficients;
inverse transforming the second number of transform coefficients to produce a prediction residual having a second size which is greater than the first size;
and
processing the prediction residual to produce a decoded video block for output or display.

2 more elements

Dependencies are inferred from the claim text.

Transforms for large video and image blocks

Life of this patent

Transforms for large video and image blocks

Life of this patent

Abstract

Claims20