SATD-Based Bypass for H.264 Transform and Quantization

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Solution Overview

Problem

In video coding, particularly in H.264 standards, determining whether transform and quantization steps can be skipped is challenging due to the absence of Sum of Absolute Differences (SAD) values, which are used in MPEG-4 for motion estimation, leading to inefficient computations.

Innovation Solution

The method employs a Sum of Absolute Transformed Differences (SATD) value, processed using the Hadamard Transform, to determine if transform and quantization steps can be bypassed by comparing it to threshold values, allowing for the skipping of these computations when all coefficients are expected to be quantized to zero.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If transform and quantization steps are performed for all blocks, then video quality is maintained, but computational complexity increases significantly

Engineering Contradiction:

Improvevideo qualityVSAvoidcomputational complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent changes the parameter used for decision-making from SAD (Sum of Absolute Differences) to SATD (Sum of Absolute Transformed Differences). By using SATD, which incorporates transform information earlier in the process, the system can more accurately predict which blocks will have all coefficients quantized to zero, enabling better bypass decisions that reduce computational complexity while maintaining video quality

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent performs the Hadamard transform before the decision to bypass transform and quantization steps. This preliminary action provides more informative SATD values that better predict the outcome of subsequent transform and quantization operations, allowing for more accurate bypass decisions that balance quality and complexity

Inventive Principle:

Principle #10Preliminary action

2Productivity

If SAD values are used to determine bypass, then computation can be reduced, but SAD is not always available in H.264 motion estimation

Engineering Contradiction:

Improvecomputation efficiencyVSAvoidcompatibility with H.264 motion estimation

Core Design Contradiction:

ProductivityVSAdaptability or versatility

Solution Approach 1:

The patent introduces SATD as an intermediary metric that bridges the gap between H.264 motion estimation requirements and bypass decision needs. SATD can be computed from the Hadamard transform results already produced during H.264 encoding, serving as a versatile indicator that works with H.264's motion estimation framework while enabling efficient bypass decisions

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent makes the bypass decision mechanism universal by using SATD, which can be derived from the Hadamard transform regardless of whether SAD was used in motion estimation. This allows the same bypass logic to work across different H.264 motion estimation configurations, enhancing adaptability and versatility

Inventive Principle:

Principle #6Universality (Multi-functionality)

3Device complexity

If all DCT coefficients are quantized to zero, then computation can be skipped, but determining this condition is difficult without SAD values

Engineering Contradiction:

Improvecomputation loadVSAvoiddetection of zero-coefficient condition

Core Design Contradiction:

Device complexityVSDifficulty of detecting and measuring

Solution Approach 1:

The patent performs the Hadamard transform as a preliminary action before making the bypass decision. This early transform provides SATD values that are strongly correlated with the energy distribution of DCT coefficients, making it easier to predict whether all coefficients will be quantized to zero without actually performing the full DCT and quantization

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The patent substitutes the direct measurement approach (computing DCT coefficients and checking if they are all zero) with an indirect measurement approach using SATD from Hadamard transform. This substitution makes the detection process simpler and more efficient, as SATD computation is less intensive than full DCT plus quantization

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Data Source

PatentUS7751631B2Bypass using sum of absolute transformed differences value (SATD) in a video coding process

Publication Date: 2010.07.06 SONY GROUP CORP

AI summary

In one embodiment, a method for bypassing transform and quantization steps in a video compression is provided. The method determines one or more threshold values that are computed for a bypass of the transform and quantization steps. A sum of absolute transformed differences (SATD) value from a motion estimation of a signal being compressed using H.26x is received. The SATD value is compared to at least one of the one or more threshold values. It is then determined if the transform and quantization can be bypassed based on the comparison. For example, if the SATD value is less than the at least one of the one or more threshold values, then it may be determined that the coefficients of the transform are expected to be quantized to zero. Accordingly, the transform and quantization steps may be bypassed.