System and method for video coding

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.

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.

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.

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.

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.