Gradual Decoding Refresh for Low-Latency Video Coding
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Solution Overview
Problem
Existing video coding technologies face challenges in achieving efficient compression and decompression with minimal latency and image quality degradation, particularly in streaming and storage scenarios with limited bandwidth.
Innovation Solution
Implementing gradual decoding refresh (GDR) techniques that utilize a GDR picture instead of intra random access point (IRAP) pictures, allowing for smoother bitrate management and reduced end-to-end delay.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If intra random access point (IRAP) pictures are used to enable random access, then random access capability is achieved, but bitrate becomes less smooth and latency increases
Solution Approach 1:
The picture is segmented into refresh regions and non-refresh regions, allowing progressive intra refresh through GDR pictures. This segmentation enables random access capability while distributing the refresh process across multiple pictures, thereby reducing the latency and bitrate spikes associated with traditional IRAP pictures.
2Quantity of substance
If compression is increased to reduce data size for streaming and storage, then bandwidth efficiency improves, but image quality may degrade
Solution Approach 1:
The invention changes the parameter of picture type from traditional IRAP to GDR picture, enabling progressive intra refresh. This allows for more efficient compression by distributing refresh operations across multiple pictures with different compression levels, maintaining image quality while reducing overall data size for streaming and storage applications.
3Loss of time
If GDR pictures are used instead of IRAP pictures, then latency is reduced and bitrate becomes smoother, but random access capability must be maintained
Solution Approach 1:
The GDR picture structure performs preliminary intra refresh operations across multiple pictures before a complete refresh is needed. This preliminary action maintains random access capability by ensuring that refresh regions are progressively updated, allowing decoders to access and decode pictures independently while maintaining smoother bitrate and reduced latency.
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.