Method and apparatus for processing video signal
A method for processing a vide signal according to the present invention comprises: determining a length of a current string, which is decoded on the basis of a sample string matching technique in a current block; determining a reference string on the basis of at least one between the length of the current string and a string vector for the current string; and predicting the current string using the reference string.
1. A method of decoding a video signal, the method comprising:
constructing a palette map for a current block encoded in a palette mode, the palette map comprises at least one palette entry;
deriving a palette index according to a predetermined scan order of the current block on a sample-by-sample basis; and
reconstructing a current sample of the current block by using one of the palette map and an escape mode, wherein a palette entry is designated from the palette map based on the derived palette index, and the escape mode is a method of restoring a sample value based on a signaled palette escape value without using the at least one palette entry of the constructed palette map,
wherein the at least one palette entry comprises at least one of a predicted palette entry and a signaled palette entry, the predicted palette entry means a palette entry reused in the current block among palette entries included in a palette map of a previous block, and the signaled palette entry indicates a palette entry not included in the palette map of the previous block among the palette entries used by the current block,
wherein the predicted palette entry is derived from information about palette entry run, the information about palette entry run is used to determine a number of zeros that precede a non-zero entry in palette entries in the previous block, and
wherein when a number of the predicted palette entry is smaller than a maximum number of palette entry, the signaled palette entry is derived.
2. The method of claim 1 , wherein the predetermined scan order is one of a horizontal traverse scan and a vertical traverse scan, and
wherein the horizontal traverse scan is a method in which an odd row of the current block is scanned from left to right and an even row is scanned from right to left and the vertical traverse scan is a method in which an odd column of the current block is scanned from top to bottom and an even column is scanned from bottom to top.
3. The method of claim 1 , wherein if a value of the derived palette index for the current sample is equal to the number of palette entries constituting the palette map of the current block, the current sample is restored based on the escape mode.
4. The method of claim 1 , wherein the escape mode is selectively used based on the number of palette entries constituting the palette map of the current block.
5. The method of claim 4 , wherein when the number of palette entries constituting the palette map of the current block is greater than 0, it is allowed to restore at least one sample of the current block based on the escape mode.
6. The method of claim 5 , wherein when the number of palette entries constituting the palette map of the current block is 0, it is not allowed to restore the current block based on the escape mode.
7. A method of encoding a video signal, the method comprising:
constructing a palette map for a current block encoded in a palette mode, the palette map comprises at least one palette entry;
deriving a palette index according to a predetermined scan order of the current block on a sample-by-sample basis; and
reconstructing a current sample of the current block by using one of the palette map and an escape mode, wherein a palette entry is designated from the palette map based on the derived palette index, and the escape mode is a method of restoring a sample value based on a signaled palette escape value without using the at least one palette entry of the constructed palette map,
wherein the at least one palette entry comprises at least one of a predicted palette entry and a signaled palette entry, the predicted palette entry means a palette entry reused in the current block among palette entries included in a palette map of a previous block, and the signaled palette entry indicates a palette entry not included in the palette map of the previous block among the palette entries used by the current block,
wherein the predicted palette entry is derived from information about palette entry run, the information about palette entry run is signaled to determine a number of zeros that precede a non-zero entry in palette entries in the previous block, and
wherein when a number of the predicted palette entry is smaller than a maximum number of palette entry, the signaled palette entry is signaled.
8. The method of claim 7 , wherein the predetermined scan order is one of a horizontal traverse scan and a vertical traverse scan, and
wherein the horizontal traverse scan is a method in which an odd row of the current block is scanned from left to right and an even row is scanned from right to left and the vertical traverse scan is a method in which an odd column of the current block is scanned from top to bottom and an even column is scanned from bottom to top.
9. The method of claim 7 , wherein if a value of the derived palette index for the current sample is equal to the number of palette entries constituting the palette map of the current block, the current sample is restored based on an escape mode.
10. The method of claim 7 , wherein the escape mode is selectively used based on the number of palette entries constituting the palette map of the current block.
11. The method of claim 10 , wherein when the number of palette entries constituting the palette map of the current block is greater than 0, it is allowed to restore at least one sample of the current block based on the escape mode.
12. The method of claim 11 , wherein when the number of palette entries constituting the palette map of the current block is 0, it is not allowed to restore the current block based on the escape mode.