Video Decoder GDR Refresh for Low-Latency Random Access
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Solution Overview
Problem
Existing video coding technologies face challenges in achieving efficient compression without sacrificing image quality, particularly in scenarios requiring random access, which often leads to high latency and inconsistent bitrates.
Innovation Solution
Implementing gradual decoding refresh (GDR) techniques by using a GDR picture instead of intra random access point (IRAP) pictures, allowing for smoother bitrate management and reduced end-to-end delay through the use of a GDR network abstraction layer unit type (GDR_NUT) in video coding layers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If intra random access point (IRAP) pictures are used to enable random access, then random access capability is achieved, but latency increases and bitrate becomes inconsistent
Solution Approach 1:
The patent segments the picture into two distinct types: GDR pictures for gradual decoding refresh and IRAP pictures for random access. This segmentation allows the system to use GDR pictures for progressive intra refresh without the high latency of full IRAP pictures, while still maintaining random access capability through periodic IRAP pictures. The decoder can progressively decode GDR pictures to achieve lower latency while IRAP pictures provide the necessary random access points.
2Adaptability or versatility
If intra random access point (IRAP) pictures are used to enable random access, then random access capability is achieved, but bitrate consistency deteriorates
Solution Approach 1:
The patent introduces a dynamic picture type system where pictures can be classified as either GDR or IRAP based on their function. GDR pictures use progressive intra refresh with smaller, more frequent updates that maintain consistent bitrate, while IRAP pictures provide periodic full refresh for random access. This dynamic classification allows the system to balance bitrate consistency with random access capability, avoiding the bitrate spikes associated with frequent IRAP pictures.
3Quantity of substance
If compression is increased to reduce video data size, then bandwidth efficiency is improved, but image quality deteriorates
Solution Approach 1:
The patent implements periodic intra refresh using GDR pictures at regular intervals within a coded video sequence. This periodic action ensures that reference pictures are refreshed systematically, preventing error propagation and maintaining image quality. The regular spacing of GDR pictures provides predictable compression patterns that improve bandwidth efficiency while the systematic refresh maintains quality standards.
Data Source
AI summary
A method of decoding a coded video bitstream implemented by a video decoder is disclosed. The method includes determining that a coded video sequence (CVS) of the coded video bitstream includes a video coding layer (VCL) network abstraction layer (NAL) unit having a gradual decoding refresh (GDR) network abstraction layer (NAL) unit type (GDR_NUT), the VCL NAL unit having the GDR_NUT containing a GDR picture; initiating decoding of the CVS at the GDR picture; and generating an image according to the CVS as decoded. A corresponding method of encoding is also disclosed.