Patent ID: 11895325
Assignee: LG ELECTRONICS INC.
Field: Audio-visual technology (Electrical engineering)
Classification: CPC H | IPC H

Claim 0:
1. A decoding apparatus for image decoding, the decoding apparatus comprising:
a memory; and
at least one processor connected to the memory, the at least one processor configured to:
obtain image information including prediction related information from a bitstream;
derive an inter prediction mode based on the prediction related information;
construct motion vector predictor candidate lists for a current block based the inter prediction mode;
derive motion vectors for the current block based on the motion vector predictor candidate lists;
derive reference picture lists for the current block, wherein the reference picture lists include an L0 reference picture list and an L1 reference picture list;
determine whether an L0 reference picture in the L0 reference picture list is a short-term reference picture;
derive a first picture order count (POC) difference between the L0 reference picture in the L0 reference picture list and current picture;
derive an L0 symmetric motion vector difference reference index;
determine whether an L1 reference picture in the L1 reference picture list is a short-term reference picture;
derive a second POC difference between the L1 reference picture in the L1 reference picture list and the current picture;
derive an L1 symmetric motion vector difference reference index; and
generate predicted samples based on the motion vectors, the L0 symmetric motion vector difference reference index and the L1 symmetric motion vector difference reference index,
wherein the motion vectors are derived based on motion vector predictors derived based on the motion vector predictor candidate lists and motion vector differences,
wherein bi-prediction is applied to the current block,
wherein the motion vector differences include an L0 motion vector difference for an L0 prediction and an L1 motion vector difference for an L1 prediction,
wherein the L1 motion vector difference is derived based on the L0 motion vector difference,
wherein the L0 symmetric motion vector difference reference index is derived based on the first POC difference and a determination that the L0 reference picture in the L0 reference picture list is the short-term reference picture not a long-term reference picture,
wherein the L0 symmetric motion vector difference reference index is derived by using a reference index for the L0 reference picture which is determined as the short-term reference picture,
wherein the L1 symmetric motion vector difference reference index is derived based on the second POC difference and a determination that the L1 reference picture in the L1 reference picture list is the short-term reference picture not a long-term reference picture, and
wherein the L1 symmetric motion vector difference reference index is derived by using a reference index for the L1 reference picture which is determined as the short-term reference picture.