System and method for video coding

1. An encoder, comprising:

circuitry; and

memory coupled to the circuitry;

wherein the circuitry, in operation:

generates a first coefficient value by applying a CCALF (cross component adaptive loop filtering) process to a first reconstructed image sample of a luma component;

sets the first coefficient value to zero in response to the first coefficient value being less than 64;

generates a second coefficient value by applying an ALF (adaptive loop filtering) process to a second reconstructed image sample of a chroma component;

generates a third coefficient value by adding the first coefficient value to the second coefficient value;

encodes a third reconstructed image sample of the chroma component using the third coefficient value;

determines a first parameter having the same value for Cb component and Cr component of the chroma component;

determines, using the first parameter, a model of entropy coding from a plurality of models; and

performs, using the model, the entropy coding of a second parameter of the CCALF process.

2. An encoding apparatus, comprising:

a block splitter, which, in operation, splits a first image into a plurality of blocks;

an intra predictor, which, in operation, predicts blocks included in the first image, using reference blocks included in the first image;

an inter predictor, which, in operation, predicts blocks included in the first image, using reference blocks included in a second image different from the first image;

a loop filter, which, in operation, filters blocks included in the first image;

a transformer, which, in operation, transforms a prediction error between an original signal and a prediction signal generated by the intra predictor or the inter predictor, to generate transform coefficients;

a quantizer, which, in operation, quantizes the transform coefficients to generate quantized coefficients; and

an entropy encoder, which, in operation, variably encodes the quantized coefficients to generate an encoded bitstream including the encoded quantized coefficients and control information,

wherein the loop filter performs:

generating a first coefficient value by applying a CCALF (cross component adaptive loop filtering) process to a first reconstructed image sample of a luma component;

setting the first coefficient value to zero in response to the first coefficient value being less than 64;

generating a second coefficient value by applying an ALF (adaptive loop filtering) process to a second reconstructed image sample of a chroma component;

generating a third coefficient value by adding the first coefficient value to the second coefficient value; and

encoding a third reconstructed image sample of the chroma component using the third coefficient value,

wherein the entropy encoder performs:

determining a first parameter having the same value for Cb component and Cr component of the chroma component;

determining, using the first parameter, a model of entropy coding from a plurality of models; and

entropy coding, using the model, a second parameter of the CCALF process.

3. A decoder, comprising:

circuitry; and

memory coupled to the circuitry;

wherein the circuitry, in operation:

determines a first parameter having the same value for Cb component and Cr component of a chroma component;

determines, using the first parameter, a model of entropy coding from a plurality of models;

performs, using the model, entropy decoding of a second parameter of a CCALF (cross component adaptive loop filtering) process;

generates a first coefficient value by applying the CCALF process to a first reconstructed image sample of a luma component;

sets the first coefficient value to zero in response to the first coefficient value being less than 64;

generates a second coefficient value by applying an ALF (adaptive loop filtering) process to a second reconstructed image sample of the chroma component;

generates a third coefficient value by adding the first coefficient value to the second coefficient value; and

decodes a third reconstructed image sample of the chroma component using the third coefficient value.

4. A decoding apparatus, comprising:

a decoder, which, in operation, decodes an encoded bitstream to output quantized coefficients;

an inverse quantizer, which, in operation, inverse quantizes the quantized coefficients to output transform coefficients;

an inverse transformer, which, in operation, inverse transforms the transform coefficients to output a prediction error;

an intra predictor, which, in operation, predicts blocks included in a first image, using a reference blocks included in the first image;

an inter predictor, which, in operation, predicts blocks included in the first image, using reference blocks included in a second image different from the first image;

a loop filter, which, in operation, filters blocks included in the first image; and

an output, which, in operation, outputs a picture including the first image,

wherein the decoder performs:

determining a first parameter having the same value for Cb component and Cr component of a chroma component;

determining, using the first parameter, a model of entropy coding from a plurality of models; and

entropy decoding, using the model, a second parameter of a CCALF (cross component adaptive loop filtering) process,

wherein the loop filter performs:

generating a first coefficient value by applying the CCALF process to a first reconstructed image sample of a luma component;

setting the first coefficient value to zero in response to the first coefficient value being less than 64;

generating a second coefficient value by applying an ALF (adaptive loop filtering) process to a second reconstructed image sample of the chroma component;

generating a third coefficient value by adding the first coefficient value to the second coefficient value; and

decoding a third reconstructed image sample of the chroma component using the third coefficient value.

5. An encoding method, comprising:

generating a first coefficient value by applying a CCALF (cross component adaptive loop filtering) process to a first reconstructed image sample of a luma component;

setting the first coefficient value to zero in response to the first coefficient value being less than 64;

generating a second coefficient value by applying an ALF (adaptive loop filtering) process to a second reconstructed image sample of a chroma component;

generating a third coefficient value by adding the first coefficient value to the second coefficient value;

encoding a third reconstructed image sample of the chroma component using the third coefficient value;

determining a first parameter having the same value for Cb component and Cr component of the chroma component;

determining, using the first parameter, a model of entropy coding from a plurality of models; and

entropy coding, using the model, a second parameter of the CCALF.

6. A decoding method, comprising:

determining a first parameter having the same value for Cb component and Cr component of a chroma component;

determining, using the first parameter, a model of entropy coding from a plurality of models;

entropy decoding, using the model, a second parameter of a CCALF (cross component adaptive loop filtering) process;

generating a first coefficient value by applying a CCALF process to a first reconstructed image sample of a luma component;

setting the first coefficient value to zero in response to the first coefficient value being less than 64;

generating a second coefficient value by applying an ALF (adaptive loop filtering) process to a second reconstructed image sample of the chroma component;

generating a third coefficient value by adding the first coefficient value to the second coefficient value; and

decoding a third reconstructed image sample of the chroma component using the third coefficient value.