Neural network-based post filter for video coding

An apparatus for coding video data comprising a processor and a non-transitory memory with instructions thereon, wherein the instructions upon execution by the processor cause the processor to:

• determine that a supplemental enhancement information (SEI) message of a bitstream includes indicators specifying one or more neural network (NN) filter model candidates or selections for a video unit or samples within the video unit;
• and
• convert between a video media file comprising the video unit and the bitstream based on the indicators,
• wherein the indicators are included in at least one of multiple levels of the SEI message, and wherein the multiple levels comprise a picture level, a slice level, a coding tree block (CTB) level, and a coding tree unit (CTU) level.

A method for storing a bitstream of a video, comprising:

• determining that a supplemental enhancement information (SEI) message of a bitstream includes indicators specifying one or more neural network (NN) filter model candidates or selections for a video unit or samples within the video unit;
• generating the bitstream based on the SEI message;
• and
• storing the bitstream in a non-transitory computer-readable recording medium,
• wherein the indicators are included in at least one of multiple levels of the SEI message, and wherein the multiple levels comprise a picture level, a slice level, a coding tree block (CTB) level, and a coding tree unit (CTU) level.