Copy from previous rows for palette mode coding

A method of encoding video data, the method comprising:

• determining a palette for encoding a block of video data to form a palette mode-encoded block, wherein the palette includes one or more palette entries, each respective palette entry having a respective palette index;
• determining a first plurality of palette indices for a first series of pixels of the palette mode-encoded block;
• locating, in the first plurality of palette indices, a reference index with respect to a second plurality of palette indices for a second series of pixels of the encoded block;
• determining that the reference index is positioned at least one line from a neighboring reference index, wherein the neighboring reference index is positioned at least two lines above a neighboring index, wherein the neighboring index is adjacent to the initial palette index of the second plurality of palette indices in the palette mode-encoded block;
• determining a run length of a run of the first plurality of palette indices, wherein a final index of the run is separated from the initial palette index of the second plurality of palette indices by at least one line of palette indices in the palette mode-encoded block;
• copying, according to a copy from previous row mode, the first plurality of palette indices included in the run as the second plurality of palette indices based on determining that the neighboring index is positioned adjacent to the initial palette index of the second plurality of palette indices;
• and
• encoding the second series of pixels of the palette mode-encoded block using the one or more palette entries of the palette based on the second plurality of palette indices.

A video decoding device comprising:

• a memory configured to store encoded video data;
• and
• one or more processors configured to:
• determine a palette for decoding a palette mode-encoded block of the encoded video data stored to the memory, wherein the palette includes one or more palette entries, each respective palette entry having a respective palette index;
• determine a first plurality of palette indices for a first series of pixels of the palette mode-encoded block;
• locate, in the first plurality of palette indices, a reference index with respect to a second plurality of palette indices for a second series of pixels of the encoded block;
• determine that the reference index is positioned at least one line from a neighboring reference index, wherein the neighboring reference index is positioned at least two lines above a neighboring index, wherein the neighboring index is adjacent to the initial palette index of the second plurality of palette indices in the palette mode-encoded block;
• determine a run length of a run of the first plurality of palette indices, wherein a final index of the run is separated from the initial palette index of the second plurality of palette indices by at least one line of palette indices in the palette mode-encoded block;
• copy, according to a copy from previous row mode, the first plurality of palette indices included in the run as the second plurality of palette indices based on the neighboring index being positioned adjacent to the initial palette index of the second plurality of palette indices;
• and
• reconstruct the second series of pixels of the palette mode-encoded block using the one or more palette entries of the palette based on the second plurality of palette indices.

A non-transitory computer-readable storage medium encoded with instructions that, when executed, cause one or more processors of a video decoding device to:

• determine a palette for decoding a palette mode-encoded block of encoded video data, wherein the palette includes one or more palette entries, each respective palette entry having a respective palette index;
• determine a first plurality of palette indices for a first series of pixels of the palette mode-encoded block;
• locate, in the first plurality of palette indices, a reference index with respect to a second plurality of palette indices for a second series of pixels of the encoded block;
• determine that the reference index is positioned at least one line from a neighboring reference index, wherein the neighboring reference index is positioned at least two lines above a neighboring index, wherein the neighboring index is adjacent to the initial palette index of the second plurality of palette indices in the palette mode-encoded block;
• determine a run length of a run of the first plurality of palette indices, wherein a final index of the run is separated from the initial palette index of the second plurality of palette indices by at least one line of palette indices in the palette mode-encoded block;
• copy, according to a copy from previous row mode, the first plurality of palette indices included in the run as the second plurality of palette indices based on the neighboring index being positioned adjacent to the initial palette index of the second plurality of palette indices;
• and
• reconstruct the second series of pixels of the palette mode-encoded block using the palette the one or more palette entries of the palette based on the second plurality of palette indices.