Direct Mode Applicability in Moving Picture Encoding
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Solution Overview
Problem
Existing moving picture encoding/decoding methods face challenges in efficiently applying the direct mode, particularly when a backward reference frame set by default cannot be utilized, leading to issues with prediction efficiency and data management.
Innovation Solution
The method provides information on whether a backward reference frame can be used in the direct mode and includes a switching procedure to alternate modes when a collocated block lacks a usable forward motion vector, allowing for efficient motion compensation with multiple block modes, including a mode without motion vector decoding.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the direct mode is applied using a backward reference frame set by default, then the encoding efficiency is improved, but the system fails when the backward reference frame cannot be utilized
Solution Approach 1:
The patent changes the parameter of reference frame selection by introducing a flag that indicates whether the backward reference frame can be used. When the flag indicates unusability, the system switches to an alternative mode, thereby adapting the encoding parameters to ensure reliability while maintaining efficiency when conditions permit.
Solution Approach 2:
The system dynamically switches between direct mode and alternative mode based on the availability of the backward reference frame. This dynamic adaptation allows the encoding process to maintain high efficiency when the direct mode is applicable while ensuring reliability by switching to an alternative when conditions change.
2Measurement precision
If motion vector decoding is performed for all blocks, then the prediction accuracy is improved, but the data amount increases
Solution Approach 1:
The patent extracts motion vector decoding only for blocks where it is necessary (when the direct mode is applicable and the backward reference frame can be used). For other blocks, the system uses an alternative mode that omits motion vector decoding, thereby reducing the overall data amount while maintaining prediction accuracy where it matters most.
Solution Approach 2:
The system applies motion vector decoding selectively to specific blocks rather than uniformly to all blocks. This local differentiation ensures high prediction accuracy for blocks that benefit from it while reducing data overhead for blocks where alternative modes suffice.
3Speed
If the direct mode is used without checking backward reference frame availability, then the processing speed is improved, but the prediction efficiency deteriorates when the frame is unavailable
Solution Approach 1:
The patent performs a preliminary check using a flag to determine whether the backward reference frame is available before attempting to use the direct mode. This preliminary action prevents processing errors and maintains prediction efficiency by avoiding direct mode when the reference frame is unavailable, while still enabling fast processing when conditions are favorable.
Data Source
AI summary
Conventionally, there has been a case that the direct mode cannot be applied effectively depending on the block. With such being the case, information indicating whether a backward reference frame set by default can be utilized in the direct mode is provided to a decoder. A switching procedure to switch to a compensation method applicable when a collocated block has no forward motion vector for effective use, and the compensation method are also provided to the decoder. Thus, it is possible to clearly determine whether the reference frame can be used in the direct mode. Further, when the frame number has no time information, it is possible to effectively send information indicating the relationship between the reference frame and the current frame. Furthermore, the alternative mode and its switching procedure of the present invention make it possible to improve the prediction performance when the direct mode cannot be applied.