Systems and methods for generating intra mode tables
An example method of video coding includes receiving a video bitstream including a plurality of blocks; receiving a video bitstream that includes a current picture, the current picture including a plurality of blocks that includes a current block. The method includes constructing an intra prediction mode table by adding an entry corresponding to an intra prediction mode to the intra prediction mode table based on one or more intra prediction modes used by one or more previously decoded blocks; and deriving an intra mode prediction list for the current block by selecting one or more entries from the constructed intra prediction mode table. The method also includes reconstructing the current block using an intra prediction mode from the intra prediction mode list.
1 . A method of video decoding performed at a computing system having memory and one or more processors, the method comprising:
receiving a video bitstream comprising a current picture, the current picture comprising a plurality of blocks including a current block,
constructing an intra prediction mode table by adding an entry corresponding to an intra prediction mode to the intra prediction mode table based on one or more intra prediction modes used by one or more previously decoded blocks;
when a block of the plurality of blocks is encoded in an inter prediction mode:
determining a corresponding intra prediction mode based on the inter prediction mode and one or more predicted samples of the block; and
updating the intra prediction mode table to include the corresponding intra prediction mode;
deriving an intra mode prediction list for the current block by selecting one or more entries from the constructed intra prediction mode table including the corresponding intra prediction mode; and
reconstructing the current block using an intra prediction mode from the intra prediction mode list.
2 . The method of claim 1 , wherein the intra prediction mode table comprises a First-In-First-Out (FIFO) queue of a predefined size, and wherein entries added to the intra prediction mode table are stored in a buffer corresponding to the FIFO queue.
3 . The method of claim 2 , wherein the predefined size is based on a bitrate for the video bitstream and/or a quantization level for the current block.
4 . The method of claim 1 , wherein the intra prediction mode table is updated each time a block from the plurality of blocks is decoded.
5 . The method of claim 1 , further comprising: performing a redundancy check prior to adding the entry to the intra prediction mode table, the redundancy check being based on the one or more intra prediction modes used by the one or more previously decoded blocks.
6 . The method of claim 5 , wherein performing the redundancy check comprises:
when an instance of a first intra prediction mode is identified at a first location in the intra prediction mode table:
removing the instance of the first intra prediction mode from the first location, and
adding a second instance of the first intra prediction mode to an end of the intra prediction mode table.
7 . The method of claim 5 , wherein performing the redundancy check comprises: determining to add the entry to the intra prediction mode table based on a respective counter for each entry of the intra prediction mode table, wherein the respective counter records a number of occurrences of intra prediction modes associated with respective entries of the intra prediction mode table.
8 . The method of claim 1 , wherein the intra prediction mode table is maintained for a first color component.
9 . The method of claim 1 , further comprising, when a block is decoded using a first intra prediction mode, adding the first intra prediction mode to the intra prediction mode table.
10 . The method of claim 1 , further comprising:
identifying a signaled flag in the video bitstream corresponding to a second block;
when the signaled flag indicates that the second block is to be decoded using the intra prediction mode table, reconstructing the second block using an intra prediction mode from the intra prediction mode table; and
when the signaled flag indicates that the second block is not to be decoded using the intra prediction mode table, reconstructing the second block without using the intra prediction mode table.
11 . The method of claim 1 , further comprising, prior to selecting the one or more entries from the intra prediction mode table, adding one or more intra prediction modes of neighboring blocks of the current block to the intra mode prediction list.
12 . The method of claim 1 , wherein the one or more previously decoded blocks are not adjacent to the current block.
13 . The method of claim 1 , further comprising:
deriving a transform set index for the current block based on the intra prediction mode table.
14 . The method of claim 1 , further comprising resetting the intra prediction mode table in accordance with a first coding level.
15 . A computing system, comprising:
control circuitry;
memory; and
one or more sets of instructions stored in the memory and configured for execution by the control circuitry, the one or more sets of instructions comprising instructions for:
receiving video data comprising a current picture, the current picture comprising a plurality of blocks;
constructing an intra prediction mode table by adding an entry corresponding to an intra prediction mode to the intra prediction mode table based on one or more intra prediction modes used by one or more previously encoded blocks;
when a block of the plurality of blocks is encoded in an inter prediction mode:
determining a corresponding intra prediction mode based on the inter prediction mode and one or more predicted samples of the block; and
updating the intra prediction mode table to include the corresponding intra prediction mode;
deriving an intra mode prediction list by selecting one or more entries from the constructed intra prediction mode table including the corresponding intra prediction mode; and
encoding a current block using an intra prediction mode from the intra prediction mode list.
16 . The computing system of claim 15 , wherein the intra prediction mode table comprises a First-In-First-Out (FIFO) queue, and wherein entries added to the intra prediction mode table are stored in a buffer assigned to the FIFO queue.
17 . The computing system of claim 15 , wherein the one or more sets of instructions further comprise instructions for signaling an indicator indicating whether the current block is to be decoded using an intra prediction mode table maintained at a decoder component, wherein the intra prediction mode table is not block-specific.
18 . The computing system of claim 15 , wherein the one or more sets of instructions further comprise instructions for signaling an indicator indicating that the decoder component is to maintain the intra prediction mode table.
19 . A non-transitory computer-readable storage medium storing a video bitstream that is generated by a video encoding method, the video bitstream comprising:
encoded information for a plurality of blocks of video data, the plurality of blocks including a current block; and
a signaled flag indicating whether the current block is to be decoded using an intra prediction mode table maintained at a decoder component, wherein the intra prediction mode table is not block-specific; and
wherein the video encoding method comprises:
constructing an intra prediction mode table by adding an entry corresponding to an intra prediction mode to the intra prediction mode table based on one or more intra prediction modes used by one or more blocks of the plurality of blocks;
when a block of the plurality of blocks is encoded in an inter prediction mode:
determining a corresponding intra prediction mode based on the inter prediction mode and one or more predicted samples of the block; and
updating the intra prediction mode table to include the corresponding intra prediction mode;
deriving an intra mode prediction list by selecting one or more entries from the constructed intra prediction mode table including the corresponding intra prediction mode; and
encoding the current block using an intra prediction mode from the intra prediction mode list.
20 . The non-transitory computer-readable storage medium of claim 19 , wherein the video bitstream further comprises a signaled indicator indicating that the decoder component is to maintain the intra prediction mode table.