GDR Video Decoding: Selective DPB Emptying for Continuous Playback
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Solution Overview
Problem
Existing video coding technologies face challenges in efficiently managing the decoded picture buffer (DPB) during random access points, leading to potential buffer overflow and disruptions in continuous playback.
Innovation Solution
The method involves a video decoder receiving a coded video bitstream containing a gradual decoding refresh (GDR) picture and a flag. Upon decoding the GDR picture, the decoder sets a flag to empty the DPB, ensuring that previously-decoded pictures are removed, thereby preventing buffer overflow and promoting continuous playback.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If previously-decoded pictures are kept in the decoded picture buffer (DPB) during random access points, then picture availability for reference is improved, but buffer overflow occurs and continuous playback is disrupted
Solution Approach 1:
The patent applies preliminary action by setting the no_output_of_prior_pics_flag in advance within the bitstream before the random access point picture arrives. This flag预先 instructs the decoder to empty the DPB of previously-decoded pictures that are not intended for output, preventing buffer overflow before it occurs while maintaining necessary picture availability for reference decoding
2Productivity
If the decoded picture buffer (DPB) is emptied at random access points, then buffer overflow is prevented and continuous playback is promoted, but picture reference availability may be reduced
Solution Approach 1:
The patent applies local quality by making the DPB emptying operation selective rather than universal. The decoder empties only those previously-decoded pictures that are marked as not intended for output (based on the no_output_of_prior_pics_flag and picture parameter set), while preserving pictures that are needed for reference. This localized approach maintains picture reference availability for necessary pictures while preventing buffer overflow
3Adaptability or versatility
If a flag is added to control DPB emptying behavior, then buffer management flexibility is improved, but bitstream complexity increases
Solution Approach 1:
The patent applies partial action by introducing a selective flag (no_output_of_prior_pics_flag) that activates only when needed for specific random access point scenarios. The flag is not always present or active, but is conditionally applied based on the picture parameter set and decoding context, providing buffer management flexibility only where required without unnecessarily complicating all bitstreams
Data Source
AI summary
A decoding device and a method of decoding implemented by a video decoder are disclosed. The decoding method includes receiving a coded video bitstream, where the coded video bitstream contains a gradual decoding refresh (GDR) picture and a first flag having a value; setting a value of a second flag equal to the value of the first flag, where the value of the second flag derived for the video decoder under test is applied for a hypothetical reference decoder (HRD); and when the value of the second flag is equal to one, emptying all picture storage buffers in a decoded picture buffer (DPB) without output of pictures contained in the DPB and setting a DPB fullness parameter to zero.