IP Verse

Methods And Apparatus For Determining Quantization Parameter Predictors From A Plurality Of Neighboring Quantization Parameters

Patent No. US11381818 (titled "Methods And Apparatus For Determining Quantization Parameter Predictors From A Plurality Of Neighboring Quantization Parameters") was filed by Interdigital Vc Holdings Inc on Jul 1, 2020.

What is this patent about?

’818 is related to the field of video encoding and decoding, specifically to the determination of quantization parameters (QPs). In video compression, QPs control the trade-off between bit rate and image quality. Efficiently encoding QP values is crucial for achieving high compression ratios without sacrificing visual fidelity. Prior art methods typically use a single neighboring QP value as a predictor for the current QP, which can be suboptimal.

The underlying idea behind ’818 is to improve the prediction of quantization parameters by using multiple neighboring QPs to form a more accurate predictor. Instead of relying on just one previous QP, the invention leverages the correlation between the current QP and several neighboring QPs to create a better estimate. This allows for a smaller difference (delta_QP) to be encoded, reducing the overhead associated with signaling QP values to the decoder.

The claims of ’818 focus on encoding and decoding image data using a quantization parameter predictor. This predictor is calculated from multiple quantization parameters of previously coded neighboring portions of the image. The core of the claims involves encoding or decoding the *difference* between the current QP and this predictor, where the predictor is the mean of the left and top neighboring QPs , and if one is unavailable, the mean of the available neighbors and the slice QP.

In practice, the encoder and decoder both use the same rule to calculate the QP predictor based on the QPs of neighboring blocks (e.g., left and top). The encoder then calculates the difference between the actual QP for the current block and the predicted QP, and encodes this difference. The decoder performs the reverse operation, calculating the same QP predictor and adding the decoded difference to obtain the actual QP value. This value is then used to dequantize the transform coefficients and reconstruct the image data.

This approach differs from prior methods that rely on a single QP value (e.g., the QP of the previous block or the slice QP) as a predictor. By considering multiple neighboring QPs, the invention can better adapt to local variations in image content and achieve a more accurate QP prediction. The use of the mean of available neighbors and the slice QP when some neighbors are unavailable ensures robustness and avoids the need for special signaling in these cases, making it more efficient than prior solutions.

How does this patent fit in bigger picture?

Technical landscape at the time

In the early 2010s when ’818 was filed, video encoding systems commonly relied on macroblocks and slices for quantization parameter (QP) adjustments. At a time when the H.264/AVC standard was widely adopted, adjusting QP values at the slice or macroblock level was typical, but this required signaling overhead. When hardware or software constraints made efficient bit allocation non-trivial, encoders often used perceptual models like texture masking to allocate more bits to smooth regions, where quality loss was more noticeable.

Novelty and Inventive Step

The examiner approved the application because the prior art failed to teach or suggest the claimed limitation where the availability of neighboring portions is a factor in contributing to the quantization parameter. While some prior art references taught quantization parameter adjustments based on various factors or using predefined values when neighboring units were unavailable, none of them specifically taught using neighboring blocks to the left and previously coded neighboring portions above the current portion being encoded, and if the portion is not available basing the parameter on the current slice.

Claims

This patent includes 17 claims, with independent claims numbered 1, 5, 10, 14, and 16. The independent claims are generally directed to methods, apparatus, and storage media for encoding and decoding image data using a quantization parameter predictor. The dependent claims generally elaborate on the specifics of the quantization parameter predictor and its application.

Key Claim Terms New

Definitions of key terms used in the patent claims.

Term (Source)Support for SpecificationInterpretation
Current quantization parameter
(Claim 1, Claim 5, Claim 10, Claim 14, Claim 16)		“The apparatus includes an encoder for encoding image data for at least a portion of a picture using a quantization parameter predictor for a current quantization parameter to be applied to the image data. The quantization parameter predictor is determined using multiple quantization parameters from previously coded neighboring portions. A difference between the current quantization parameter and the quantization parameter predictor is encoded for signaling to a corresponding decoder.”The quantization parameter to be applied to the image data currently being encoded or decoded.
Previously coded neighboring portions
(Claim 1, Claim 5, Claim 10, Claim 14, Claim 16)		“The apparatus includes an encoder for encoding image data for at least a portion of a picture using a quantization parameter predictor for a current quantization parameter to be applied to the image data. The quantization parameter predictor is determined using multiple quantization parameters from previously coded neighboring portions. A difference between the current quantization parameter and the quantization parameter predictor is encoded for signaling to a corresponding decoder.”Portions of the image that have already been encoded or decoded and are adjacent to the portion currently being processed, used to determine the quantization parameter predictor.
Quantization parameter for a current slice
(Claim 1, Claim 5, Claim 10, Claim 14, Claim 16)		“The syntax in the MPEG-4 AVC Standard allows quantization parameters to be different for each slice and macroblock (MB). The value of a quantization parameter is an integer and is in the range of 0-51. The initial value for each slice can be derived from the syntax element pic_init_qp_minus26.”A quantization parameter associated with the current slice of the image being processed, used as a fallback when neighboring portions are unavailable.
Quantization parameter predictor
(Claim 1, Claim 5, Claim 10, Claim 14, Claim 16)		“The apparatus includes an encoder for encoding image data for at least a portion of a picture using a quantization parameter predictor for a current quantization parameter to be applied to the image data. The quantization parameter predictor is determined using multiple quantization parameters from previously coded neighboring portions. A difference between the current quantization parameter and the quantization parameter predictor is encoded for signaling to a corresponding decoder.”A value used to predict the current quantization parameter, derived from quantization parameters of previously coded neighboring portions.

Patent Family

Patent Family

File Wrapper

The dossier documents provide a comprehensive record of the patent's prosecution history - including filings, correspondence, and decisions made by patent offices - and are crucial for understanding the patent's legal journey and any challenges it may have faced during examination.

  • Date

    Description

  • Get instant alerts for new documents

US11381818

INTERDIGITAL VC HOLDINGS INC
Application Number
US16918069
Filing Date
Jul 1, 2020
Status
Granted
Expiry Date
Jun 8, 2031
External Links
Slate, USPTO, Google Patents