NAL Unit Header Design for Scalable Video Coding

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Solution Overview

Problem

Existing video coding standards, such as HEVC, face limitations in scalability and bitstream management, particularly in preventing the NAL unit header from emulating a start code prefix and ensuring efficient signaling of spatial and temporal layer identifiers without increasing bit overhead.

Innovation Solution

The proposed solution involves modifying the NAL unit header by using a syntax element 'temporal_id_plus1' to ensure it is always greater than 0, and allowing the reserved syntax element to include an all-zero value, thereby expanding its range and preventing emulation of a start code prefix, while maintaining efficient scalability signaling.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If the NAL unit header uses a syntax element to signal temporal identification, then temporal scalability is enabled, but the header may emulate a start code prefix causing decoding errors

Engineering Contradiction:

Improvetemporal scalabilityVSAvoiddecoding accuracy

Core Design Contradiction:

Adaptability or versatilityVSReliability

Solution Approach 1:

The patent applies preliminary anti-action by preemptively preventing the emulation of start code prefixes through the design of the temporal_id syntax element. By ensuring that temporal_id values and their encoding schemes are designed to never produce byte sequences that match start code prefixes (0x00 0x00 0x01 or 0x00 0x00 0x00 0x01), the patent eliminates the potential harm before it can occur during decoding operations.

Inventive Principle:

Principle #9Preliminary anti-action

2Adaptability or versatility

If the NAL unit header reserves syntax elements for future extensions, then adaptability is improved, but bit overhead increases

Engineering Contradiction:

Improvespatial scalabilityVSAvoidbit overhead

Core Design Contradiction:

Adaptability or versatilityVSQuantity of substance

Solution Approach 1:

The patent applies universality by designing the reserved syntax elements in the NAL unit header to serve multiple functions. The same reserved bits that could signal future spatial scalability features also maintain backward compatibility with existing HEVC standards, allowing a single header structure to support both current and future video coding requirements without requiring separate signaling mechanisms.

Inventive Principle:

Principle #6Universality (Multi-functionality)

3Reliability

If the NAL unit header structure is modified to prevent start code emulation, then decoding reliability is improved, but device complexity increases

Engineering Contradiction:

Improvedecoding reliabilityVSAvoidheader processing complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent applies parameter changes by modifying the encoding parameters of the temporal_id syntax element. By changing how temporal identification is represented in the bitstream (using specific value ranges and encoding schemes), the patent simultaneously achieves both goals: preventing start code emulation while maintaining simple, efficient decoding logic that does not require complex validation rules.

Inventive Principle:

Principle #35Parameter changes

Data Source

PatentUS9686542B2Network abstraction layer header design

Publication Date: 2017.06.20 QUALCOMM INC

AI summary

A video processing device can receive in an encoded bitstream of video data a network abstraction layer (NAL) unit and parse a first syntax element in a header of the NAL unit to determine a temporal identification (ID) for the NAL unit, wherein a value of the first syntax element is one greater than the temporal identification.