Video Syntax Signaling for Bi-Predictive Slice Decoding
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Solution Overview
Problem
Existing video coding standards face challenges in efficiently signaling syntax elements, particularly in scenarios where reference picture lists indicate bi-predictive slices, leading to inefficiencies in decoding processes.
Innovation Solution
Implementing methods and apparatuses that allow decoders to determine and constrain syntax elements based on the presence of reference picture lists and bi-predictive slices, using enabled flags for temporal motion vector predictors, and applying scaling ratio offsets for improved video coding efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If reference picture lists are signaled in the picture header for bi-predictive slices, then prediction accuracy is improved, but decoding complexity and processing time increase
Solution Approach 1:
The patent applies local quality by differentiating processing between bi-predictive and non bi-predictive slices. The decoder determines slice type and applies different constraint rules: for bi-predictive slices, full reference picture list signaling is used for accurate prediction, while for non bi-predictive slices, constrained rules limit the reference picture list to reduce complexity. This localized approach optimizes each slice type appropriately.
Solution Approach 2:
The patent introduces dynamic constraint rules that adapt based on slice type determination. The decoder dynamically adjusts the reference picture list constraints during decoding: when bi-predictive mode is detected, more flexible reference selection is allowed; when non bi-predictive mode is detected, stricter constraints are applied. This dynamic adaptation resolves the contradiction between accuracy and complexity.
2Productivity
If temporal motion vector predictors are enabled for inter prediction, then coding efficiency is improved, but computational complexity increases
Solution Approach 1:
The patent applies preliminary action by pre-defining constraint rules for temporal motion vector predictors based on slice type. Before actual motion vector prediction is performed, the decoder determines whether the slice is bi-predictive or non bi-predictive and pre-applies the appropriate constraints. This preliminary determination prevents unnecessary computational complexity while maintaining coding efficiency.
Solution Approach 2:
The patent changes the parameter of temporal motion vector predictor availability based on slice type. For non bi-predictive slices, the constraint rules effectively disable or limit temporal motion vector predictors, reducing computational complexity. For bi-predictive slices, full temporal motion vector predictor functionality is maintained to preserve coding efficiency. This parameter change resolves the contradiction.
3Measurement precision
If syntax elements are fully signaled in the picture header, then decoding accuracy is improved, but bit rate increases
Solution Approach 1:
The patent extracts and removes unnecessary syntax element signaling for non bi-predictive slices. By identifying slice type, the decoder can omit signaling of certain reference picture list and temporal motion vector predictor syntax elements in non bi-predictive slices, where these elements would not be used anyway. This extraction reduces bit rate without affecting decoding accuracy for the actual slice type being decoded.
Solution Approach 2:
The patent applies partial action by signaling syntax elements selectively based on slice type. Instead of always signaling all reference picture list and predictor elements (excessive action), the decoder signals only what is necessary for the current slice type. For non bi-predictive slices, certain elements are partially signaled or omitted, reducing bit rate while maintaining sufficient decoding accuracy.
Data Source
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AI summary
Methods and apparatuses for video coding are provided. The method includes obtaining, by a decoder, an enabled flag which specifies whether one or more temporal motion vector predictors are enabled for inter prediction for one or more slices associated with a picture header of a picture, wherein a value of the enabled flag is equal to 0 when a plurality of offsets applied to a size of the picture for scaling ratio calculation satisfy a first condition.