Synthetic Random Access Point via Intra-Refresh Video Coding
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Solution Overview
Problem
Existing video coding technologies face challenges with compression delay and bit-rate jitter due to the use of I-frames, and the elimination of I-frames complicates the definition of random access points, which are crucial for error resiliency and VCR-like functionalities.
Innovation Solution
The implementation of a synthetic random access point, or 'patch' frame, is formed by copying and combining intra-coded subsections from multiple predictive-coded frames, allowing for the creation of a random access point without requiring I-frames, enabling efficient bit-rate smoothing and error resilience.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If I-frames are used to create random access points, then error resiliency and VCR-like functionalities are maintained, but compression delay and bit-rate jitter increase
Solution Approach 1:
The patent divides the video stream into segments with periodic intra-refresh intervals, creating synthetic random access points without requiring full I-frames. This segmentation allows error resiliency at specific intervals while maintaining efficient P-frame compression between intervals, thus reducing compression delay while preserving reliability.
Solution Approach 2:
The patent applies intra-refresh only to specific macroblocks or regions at periodic intervals rather than encoding entire frames as I-frames. This local application of intra-coding provides error resiliency where needed while maintaining inter-frame compression efficiency elsewhere, eliminating compression delay associated with full I-frames.
2Reliability
If I-frames are used to create random access points, then error resiliency is maintained, but bit-rate fluctuations increase
Solution Approach 1:
By segmenting the video stream into periodic intra-refresh intervals rather than using full I-frames, the patent distributes the bit-rate impact of intra-coding across multiple smaller segments. This prevents large bit-rate spikes associated with I-frames while maintaining error resiliency through periodic refresh points.
Solution Approach 2:
The patent applies intra-refresh locally to specific macroblocks or regions rather than entire frames, reducing the bit-rate impact of intra-coding. This local application maintains error resiliency in critical areas while avoiding the substantial bit-rate fluctuations that would result from full I-frame encoding.
3Quantity of substance
If I-frames are eliminated for bit-rate smoothing, then bit-rate fluctuations are reduced, but definition of random access points becomes complex
Solution Approach 1:
The patent creates synthetic random access points through periodic intra-refresh segmentation of the video stream. This provides clearly defined random access points with simple periodic timing, eliminating the complexity that would arise from eliminating all structured refresh points while maintaining bit-rate stability through avoidance of full I-frames.
4Ease of operation
If full I-frames are used for random access, then random access functionality is provided, but compression efficiency decreases
Solution Approach 1:
The patent segments intra-refresh application to specific macroblocks or regions at periodic intervals rather than encoding complete I-frames. This provides random access functionality at defined intervals while maintaining efficient P-frame compression for the majority of the video stream, thus preserving compression efficiency while enabling random access.
Data Source
AI summary
A random access point is generated in a stream of coded digital pictures containing a plurality of predictive coded frames that have two or more predictive coded frames in which one or more subsections of each of the two or more predictive coded frames are intra coded. Information is added to a stream of digital pictures that identifies for a decoder which of two or more predictive-coded frames in the stream have intra-coded subsections at different portions that can be combined to form a patch frame.