Video Decoder Buffer Management for Random Access
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Solution Overview
Problem
Existing video coding technologies face inefficiencies in managing reference picture memory, particularly when random access is used, leading to unnecessary decoding and storage of unused pictures, which can impact processing efficiency and battery life in mobile devices.
Innovation Solution
The implementation of techniques that determine whether an open decoding refresh (ODR) picture is used as a random access point, allowing the video decoder to selectively decode and store only necessary pictures by marking unused pictures for removal from the decoded picture buffer (DPB) and skipping the output of data for pictures with display orders less than the ODR picture.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If all pictures are decoded and stored in the decoded picture buffer (DPB) for random access, then random access functionality is enabled, but memory storage is wasted and processing efficiency deteriorates due to decoding unnecessary pictures
Solution Approach 1:
The patent applies the discarding principle by selectively removing unused pictures from the DPB based on usage flags. When a picture is determined to be unused for random access, it is marked for removal and discarded from the buffer. This resolves the contradiction by maintaining only necessary pictures in memory, improving processing efficiency while preserving random access capability for needed pictures.
Solution Approach 2:
The patent changes the state parameter of pictures in the DPB by introducing a usage flag that indicates whether each picture is used for random access. This parameter change enables the system to differentiate between necessary and unnecessary pictures, allowing selective retention and discarding. The flag acts as a control parameter that transforms the DPB management from blanket storage to selective storage, resolving the efficiency-capability contradiction.
2Reliability
If all pictures are decoded and stored in the decoded picture buffer (DPB), then reference picture availability is maximized, but energy consumption increases due to unnecessary decoding and storage operations
Solution Approach 1:
The patent discards unnecessary pictures from the DPB by setting usage flags to indicate non-usage. This eliminates energy-wasting decoding and storage operations for pictures that will not be used as reference pictures. The principle resolves the contradiction by maintaining reference picture availability for needed pictures while removing unnecessary ones, thereby reducing energy consumption without compromising reliability.
Solution Approach 2:
The patent applies partial action by decoding and storing only the subset of pictures that are actually needed for random access, rather than decoding all pictures. By using usage flags to identify necessary pictures, the system performs exactly the required amount of decoding work—no more, no less—thereby reducing energy consumption while maintaining sufficient reference picture availability for reliable operation.
3Productivity
If unused pictures are removed from the decoded picture buffer (DPB), then storage management is improved and processing efficiency increases, but random access functionality may be compromised
Solution Approach 1:
The patent carefully applies discarding by first identifying unused pictures through usage flags before removal. This ensures that only pictures not needed for random access are discarded, while pictures required for random access are retained. The principle resolves the contradiction by enabling efficient storage management through selective discarding while preserving random access functionality for necessary pictures.
Solution Approach 2:
The patent uses usage flags as feedback mechanisms to track which pictures are needed for random access. This feedback information guides the DPB management decisions, ensuring that pictures required for random access are not removed. The feedback loop resolves the contradiction by providing real-time information about picture usage requirements, allowing the system to maintain random access functionality while improving processing efficiency through selective retention.
Data Source
AI summary
In one example, a video decoder is configured to determine, from data associated with an open decoding refresh (ODR) picture of video data, an identifier for a previous picture of the video data, determine whether the previous picture is currently stored in a reference picture memory, and decode only data for pictures of the video data having display order values that are greater than a display order value of the ODR picture, when the previous picture is not stored in the reference picture memory. In another example, a video encoder is configured to encode an open decoding refresh (ODR) picture, determine a previously coded picture having a display order value less than a display order value of the ODR picture and having a temporal identifier value equal to zero, and signal syntax data for the ODR picture representative of an identifier of the determined previously coded picture.