GPB Frame Reference Picture List Duplication
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Solution Overview
Problem
In video coding, the existing techniques for constructing reference picture lists for generalized P/B (GPB) frames are redundant, leading to increased computational costs and bit savings challenges due to redundant syntax elements and decoding processes.
Innovation Solution
The proposed solution involves coding a video frame as a GPB frame with identical reference picture lists, where only the first reference picture list is signaled and constructed, and the second list is duplicated, eliminating redundant syntax elements and decoding processes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If both first and second reference picture lists are signaled and constructed for GPB frames, then complete bidirectional prediction capability is maintained, but redundant syntax elements and decoding processes increase computational cost and reduce coding efficiency
Solution Approach 1:
The patent applies the copying principle by creating the second reference picture list as a duplicate of the first reference picture list for GPB frames. Instead of independently signaling and constructing both lists, the encoder signals only the first list and generates the second list by copying the first list's reference pictures and construction parameters. This eliminates redundant syntax elements while maintaining complete bidirectional prediction capability, directly resolving the technical contradiction between coding efficiency and construction complexity.
2Loss of information
If redundant syntax elements for both reference picture lists are coded, then all reference picture information is explicitly transmitted, but bit rate increases and compression performance deteriorates
Solution Approach 1:
The patent applies the extraction principle by removing redundant syntax elements from the bitstream for GPB frames. Specifically, when the second reference picture list is constructed by copying the first list, the patent eliminates the need to signal num_ref_idx_l1_active_minus1 and ref_pic_list_modification_commands_l1 in the slice header. This extraction of redundant information maintains complete reference picture information transmission while significantly reducing bit rate and improving compression performance.
3Reliability
If both reference picture lists are independently constructed at the decoder, then accurate reference picture reconstruction is achieved, but decoding computational load and processing time increase
Solution Approach 1:
The patent applies the preliminary action principle by pre-establishing the relationship between the first and second reference picture lists through the gpb_frame_flag and list1_copy_flag syntax elements. The decoder uses these preliminary indicators to determine whether to construct the second list by copying the first list, avoiding the need to independently process both lists. This preliminary action maintains accurate reference picture reconstruction while significantly reducing decoding computational load and processing time.
Data Source
AI summary
This disclosure relates to techniques for indicating that a video frame is coded as a generalized P/B (GPB) frame in order to reduce a cost of coding and constructing a second reference picture list in video coding. For a GPB frame, which has identical reference picture lists, signaling and constructing both the first and second reference picture lists may be redundant. The techniques of this disclosure may include coding syntax elements indicating that the video frame is coded as the GPB frame, and coding syntax elements indicating a number of reference pictures and reference picture list construction commands for only a first reference picture list. The techniques also include constructing the first reference picture list based on the syntax elements, and then creating the second reference picture list as a duplicate of the first reference picture list.