Video Random Access Unit Types for Mid-Bitstream CRA Pictures

Resolve Bottlenecks,
Find Innovative SolutionsGenerate Solutions

Solution Overview

Problem

Existing video codec standards limit the flexibility of random access points in video bitstreams, restricting the ability to efficiently perform operations like fast forwarding, rewinding, and seamless switching between video streams.

Innovation Solution

Introduce clean random access (CRA) pictures that can be placed mid-bitstream and allow for potentially non-decodable leading pictures, using flags or indicators to manage these non-decodable pictures, and define new unit types for RAP pictures to simplify mapping to container formats.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If traditional video codec standards are used with limited random access points, then decoding complexity is reduced, but the flexibility and adaptability of video delivery and editing operations deteriorate

Engineering Contradiction:

Improveflexibility of random access pointsVSAvoiddecoder complexity

Core Design Contradiction:

Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The video bitstream is segmented into multiple access units, each containing a CRA picture that can serve as an independent random access point. This segmentation allows the video stream to be divided into manageable sections that can be decoded independently, enhancing flexibility without overwhelming the decoder with entire sequence dependencies

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

CRA pictures serve as intermediary reference points between traditional IDR pictures. These intermediate access points provide decodable reference frames that mediate between random access requirements and decoding complexity, allowing flexible entry points while maintaining manageable decoder state requirements

Inventive Principle:

Principle #24Intermediary (Mediator)

2Adaptability or versatility

If CRA pictures with non-decodable leading pictures are allowed mid-bitstream, then the number of access points increases, but the complexity of managing leading pictures and their decodability increases

Engineering Contradiction:

Improvenumber of access pointsVSAvoidmanagement of leading pictures

Core Design Contradiction:

Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The decoder is prepared in advance for potential non-decodable leading pictures by implementing logic to detect and handle such cases. Flags and syntax elements are included in the bitstream to pre-indicate the presence of non-decodable leading pictures, allowing the decoder to prepare appropriate handling strategies before encountering these pictures

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The bitstream structure itself carries information about its own decodability characteristics through flags and syntax elements. The leading pictures contain embedded metadata that enables them to self-identify their decodability status, reducing the burden on external management systems to track and manage their decodability state

Inventive Principle:

Principle #25Self-service

3Adaptability or versatility

If mid-bitstream CRA pictures are allowed with non-decodable leading pictures, then random access flexibility is improved, but bitstream structure complexity increases

Engineering Contradiction:

Improverandom access flexibilityVSAvoidbitstream structure

Core Design Contradiction:

Adaptability or versatilityVSDevice complexity

Solution Approach 1:

CRA pictures serve multiple functions simultaneously: they act as random access points, provide reference frames for subsequent decoding, and can have associated leading pictures for temporal continuity. This multi-functionality consolidates several features into a single picture type, reducing the need for multiple specialized structures

Inventive Principle:

Principle #6Universality (Multi-functionality)

Solution Approach 2:

The bitstream structure uses parameters such as `broken_link_flag` and `rasl_pic_cnt` to dynamically indicate the presence and characteristics of non-decodable leading pictures. These parameters allow the bitstream to adapt its structure based on content requirements without fundamentally changing the underlying syntax framework

Inventive Principle:

Principle #35Parameter changes

4Adaptability or versatility

If more access points are introduced for adaptive video delivery, then video delivery flexibility is improved, but the complexity of mapping units to container formats increases

Engineering Contradiction:

Improveadaptive video delivery flexibilityVSAvoidmapping to container format

Core Design Contradiction:

Adaptability or versatilityVSDevice complexity

Solution Approach 1:

Access units containing CRA pictures are segmented as independent mappable entities to container formats. Each access unit can be independently packaged and delivered, simplifying the mapping process compared to treating entire video sequences as single units. This segmentation aligns with container format requirements for discrete, deliverable units

Inventive Principle:

Principle #1Segmentation

Data Source

PatentUS20260082080A1Constraints and unit types to simplify video random access

Publication Date: 2026.03.19 MICROSOFT TECHNOLOGY LICENSING LLC

AI summary

Disclosed herein are innovations for bitstreams having clean random access (CRA) pictures and/or other types of random access point (RAP) pictures. New type definitions and strategic constraints on types of RAP pictures can simplify mapping of units of elementary video stream data to a container format. Such innovations can help improve the ability for video coding systems to more flexibly perform adaptive video delivery, production editing, commercial insertion, and the like.