Method and apparatus for adaptive loop filter with virtual boundaries and multiple sources for video coding

A video coding system utilizing chroma ALF or CCALF with multi-source or high-degree taps. According to the method, reconstructed pixels are received, wherein the reconstructed pixels comprise a current block and the current block comprises a luma block and one or more chroma blocks. A filtered chroma output is derived from a chroma ALF or CCALF (Cross-Component ALF) for a current chroma sample in one of said one or more chroma blocks, wherein the chroma ALF comprises one or more multiple-source chroma samples or luma sample from the current block in a first footprint of the chroma ALF, or wherein the CCALF comprises one or more multiple-source luma samples from the luma block in a second footprint of the CCALF. A filtered-reconstructed first chroma block is provided, wherein the filtered-reconstructed first chroma block comprises the filtered chroma output.