US 9036701

US Patent 9036701: Summary and Claim Analysis

Title: Method and apparatus for providing complexity balanced entropy coding

Assignee:

• Current: Nokia Technologies Oy
• Original: Nokia Inc

Inventors: Jani Lainema, Kemal Ugur, Antti Olli Hallapuro

Filing Date: July 27, 2011

Issue Date: May 19, 2015

Abstract:
The patent describes a method, apparatus, and computer program product designed for efficient video coding and decoding through complexity-balanced entropy coding. This approach aims to achieve high video coding and decoding capability while minimizing complexity costs. The method involves categorizing video content's syntax elements into two groups based on their frequency of occurrence. Symbols in the first category (less frequent) undergo entropy coding with context updating. In contrast, symbols in the second category (more frequent) bypass context updating during their entropy coding.

Plain-Language Overview of Independent Claims:

• Independent Claim 1 (Method):
  This claim describes a process for coding video data. It involves setting a threshold for how often specific video data parts (syntax elements) are expected to appear. Based on this threshold, these elements are sorted into two groups: a first category for elements that occur more frequently than the threshold, and a second category for those that occur less frequently. The method then uses two different approaches for compressing these elements (entropy coding): the more frequent elements in the first category are coded with "context updating" (an adaptive method that adjusts based on recent data), while the less frequent elements in the second category are coded without this context updating, simplifying the process.
  (Note: The claim text states "syntax elements which occur greater than the frequency of occurrence threshold are categorized into the first category and syntax elements which occur less than the frequency of occurrence are categorized into the second category". However, the detailed description states, "the first category includes symbols that occur relatively infrequently and the second category includes symbols that occur relatively frequently." And also, "those symbols that are expected to occur more frequently than the threshold frequency may be determined to be in the second category while those symbols that are expected to occur less frequently than the threshold frequency may be determined to be in the first category." For the claim summary, the claim wording is strictly followed, noting this potential inconsistency in categorization definition between the claim and the detailed description.)

• Independent Claim 8 (Apparatus):
  This claim defines an electronic device (apparatus) equipped with at least one processor and memory containing computer program code. This apparatus is designed to perform the method described in Claim 1. Specifically, it determines a frequency threshold for video syntax elements, categorizes these elements into two groups based on that threshold (more frequent elements into the first category, less frequent into the second), and then entropy codes them differently: with context updates for the first category and bypassing context updates for the second category.

• Independent Claim 15 (Computer Program Product):
  This claim covers a non-transitory computer-readable storage medium (like a hard drive or flash memory) that stores computer instructions. When a computer runs these instructions, it performs the method outlined in Claim 1. This includes determining a frequency threshold for video syntax elements, categorizing them into two groups (more frequent elements into the first category, less frequent into the second), and then applying entropy coding with context updates for the first category and without context updates for the second category.

Litigation and Legal Status:
As of April 26, 2026, US Patent 9036701 is Active and is set to expire on April 28, 2032.

The patent family is currently involved in litigation, with multiple cases filed:

• US case filed in Texas Western District Court.
• US case filed in the International Trade Commission (Case 337-TA-1448).
• A PTAB case, IPR2025-01345, was filed (marked as Settlement).
• Another US case filed in the International Trade Commission (Case 337-TA-3821).
• First worldwide family litigation has been filed.
• US case filed in California Central District Court (Case 2:25-cv-03053).
• US case filed in Georgia Northern District Court (Case 1:25-cv-01871).

A search for "US9036701 CAFC 2026 dockets" and "CAFC docket 9036701" did not return any specific docket entries for the Federal Circuit (CAFC) in 2026 directly related to US9036701 at this time. While an Inter Partes Review (IPR2025-01345) was filed in 2025, which could lead to a CAFC appeal in 2026, no such appeal is explicitly listed in the provided information or found in the targeted search.

US Patent 9,036,701 has been involved in several litigation cases. The details are as follows:

1. US District Court for the Western District of Texas

   • Plaintiff(s): Not explicitly stated in the provided snippet, but likely Nokia Technologies Oy as the current assignee.
   • Defendant(s): Not explicitly stated in the provided snippet.
   • Jurisdiction: Texas Western District Court
   • Case Number: 1:25-cv-00523
   • Filing Date: Not explicitly provided in the snippet, but the case number suggests 2025.
   • Outcome/Current Status: Active litigation.

2. US International Trade Commission (ITC)

   • Plaintiff(s): Not explicitly stated in the provided snippet, but likely Nokia Technologies Oy as the current assignee.
   • Defendant(s): Not explicitly stated in the provided snippet.
   • Jurisdiction: International Trade Commission
   • Case Number: 337-TA-1448
   • Filing Date: Not explicitly provided in the snippet.
   • Outcome/Current Status: Active litigation.

3. Patent Trial and Appeal Board (PTAB)

   • Plaintiff(s) (Petitioner): Unified Patents
   • Defendant(s) (Patent Owner): Not explicitly stated in the provided snippet, but would be Nokia Technologies Oy.
   • Jurisdiction: Patent Trial and Appeal Board (PTAB)
   • Case Number: IPR2025-01345
   • Filing Date: Not explicitly provided in the snippet, but the case number suggests 2025.
   • Outcome/Current Status: Settlement.

4. US International Trade Commission (ITC)

   • Plaintiff(s): Not explicitly stated in the provided snippet, but likely Nokia Technologies Oy as the current assignee.
   • Defendant(s): Not explicitly stated in the provided snippet.
   • Jurisdiction: International Trade Commission
   • Case Number: 337-TA-3821
   • Filing Date: Not explicitly provided in the snippet.
   • Outcome/Current Status: Active litigation.

5. US District Court for the Central District of California

   • Plaintiff(s): Not explicitly stated in the provided snippet, but likely Nokia Technologies Oy as the current assignee.
   • Defendant(s): Not explicitly stated in the provided snippet.
   • Jurisdiction: California Central District Court
   • Case Number: 2:25-cv-03053
   • Filing Date: Not explicitly provided in the snippet, but the case number suggests 2025.
   • Outcome/Current Status: Active litigation.

6. US District Court for the Northern District of Georgia

   • Plaintiff(s): Not explicitly stated in the provided snippet, but likely Nokia Technologies Oy as the current assignee.
   • Defendant(s): Not explicitly stated in the provided snippet.
   • Jurisdiction: Georgia Northern District Court
   • Case Number: 1:25-cv-01871
   • Filing Date: Not explicitly provided in the snippet, but the case number suggests 2025.
   • Outcome/Current Status: Active litigation.

Proceedings overview

One AIA trial proceeding has been filed against US Patent 9,036,701. This proceeding, IPR2025-01345, was terminated due to settlement before a final written decision was issued. This gives a defendant limited insight into the patent's validity as no claims were invalidated or sustained by the PTAB.

IPR2025-01345 — Snap Inc. et al. v. Nokia Technologies Oy

• Type: Inter Partes Review
• Filed: 2025-08-21
• Status: Terminated-Settled. The proceeding concluded without a Final Written Decision due to a settlement between the parties.
• Judge panel: Information regarding the specific judge panel for this IPR is not publicly available in the termination record.
• Petition grounds: Details regarding the specific claims challenged and prior art asserted are not publicly available in the termination record. Typically, IPR petitions challenge claims under 35 U.S.C. §§ 102 and/or 103.
• Institution decision: The proceeding was terminated as "Terminated-Settled" on 2026-01-23. This typically indicates a settlement occurred before an institution decision was rendered.
• Final Written Decision: No Final Written Decision was issued as the proceeding was terminated due to settlement.
• Settlement / termination: The proceeding was terminated on 2026-01-23. The specific terms of the settlement are confidential.
• Appeal: No appeal was filed with the Federal Circuit, which is typical for proceedings terminated by settlement prior to a Final Written Decision.
• Defensive value: This proceeding does not provide a definitive ruling on the patentability of any claims of US 9,036,701. The settlement means the claims challenged by Snap Inc. et al. remain untested by the PTAB. However, the fact that a settlement occurred suggests some commercial interest or concern from Snap Inc. et al. regarding the patent.

Strategic summary

No claims of US 9,036,701 have been canceled or sustained by the PTAB, as the single filed IPR, IPR2025-01345, was terminated due to settlement. Therefore, all claims of the patent remain untested by the PTAB in terms of patentability challenges.

Regarding the estoppel landscape, since IPR2025-01345 was terminated due to settlement before a Final Written Decision, statutory estoppel under 35 U.S.C. § 315(e)(1) and (2) does not apply to the petitioner (Snap Inc. et al.) or its privies. This means that Snap Inc. et al. (and their privies) are not barred from raising any ground that they raised or reasonably could have raised in the IPR in future proceedings, although contractual estoppel may apply depending on the settlement terms. For a defendant currently being asserted against, this means that prior-art grounds that could have been raised in IPR2025-01345 are generally still available for a new IPR petitioner, subject to the one-year time bar for IPR petitions from the date a defendant is served with a complaint alleging infringement.

There are no apparent pattern signals such as multiple IPRs from the same petitioner or aggressive PTAB appeals by the patent owner based on the provided data. Unified Patents is not listed as a petitioner in this proceeding.

Recommended next steps

As there are no active PTAB proceedings and the sole filed IPR was settled without a final decision, there are no immediate trial-stage milestones to monitor. For a potential defendant, the absence of an FWD means no claims have been invalidated by the PTAB, which could be seen as a challenge for an IPR-based defense. However, the lack of a decision also means no claims have been affirmed as patentable over the prior art by the PTAB.

Given the settlement, it would be prudent to investigate if the settlement agreement is publicly available or if any related court filings shed light on the scope of the agreement.

Inventors

• Jani Lainema (Nokia Inc)
• Kemal Ugur (Nokia Inc)
• Antti Olli Hallapuro (Nokia Inc)

Original assignee

The original assignee named on the issued patent US9036701B2 is Nokia Inc. Nokia's primary line of business is telecommunications, consumer electronics, and information technology. Nokia Technologies Oy, the current assignee, develops and licenses Nokia innovations. Nokia is an operating company and is currently active.

Assignment timeline

• 2012-03-23 (executed) / recorded 2012-04-05 — Reel 028350/0949
  • Conveyance: Assignment
  • Assignor: Nokia Inc.
  • Assignee: Nokia Corporation
  • Correspondent: Brian M. Dingman, Alston & Bird LLP, 950 F Street, NW, Washington, DC 20004
  • Context: Internal corporate restructuring/reassignment.
• 2015-04-22 (executed) / recorded 2015-05-13 — Reel 033621/0434
  • Conveyance: Assignment
  • Assignor: Nokia Corporation
  • Assignee: Nokia Technologies Oy
  • Correspondent: Brian M. Dingman, Alston & Bird LLP, 950 F Street, NW, Washington, DC 20004. This correspondent recurs in this chain.
  • Context: Internal corporate restructuring/reassignment.

Timeline diagram

timeline
    title Ownership of US 9036701
    2011 : Filed by Nokia Inc
    2012 : Assigned to Nokia Corp
    2015 : Assigned to Nokia Technologies Oy
         : Issued
    2025 : First infringement suit filed (TX W)

NPE / troll-pattern signals

1. Shell-entity transfer — not present. All transfers are between known operating entities (Nokia Inc., Nokia Corporation, Nokia Technologies Oy).
2. Known asserter in the chain — not present. None of the assignees (Nokia Inc., Nokia Corporation, Nokia Technologies Oy) are known NPEs.
3. Repeat correspondent across the chain — present. Brian M. Dingman of Alston & Bird LLP is listed as the correspondent for both the 2012-04-05 assignment (Reel 028350/0949) and the 2015-05-13 assignment (Reel 033621/0434).
4. Cascading transfers — not present. There are two transfers over a span of three years, which does not constitute cascading transfers.
5. Pre-litigation transfer — not present. The patent was issued on 2015-05-19. The earliest reported litigation was filed in 2025. There are no assignment records within 6 months prior to this litigation filing.
6. Bankruptcy fire-sale — not present. The assignment records do not indicate any bankruptcy proceedings for the assignors.
7. Privateering — unclear. While Nokia Technologies Oy is primarily a licensing entity, there is no public information to suggest they are asserting this patent on behalf of a competitor against another.
8. Defensive aggregator (anti-NPE) — not present. The chain ends at Nokia Technologies Oy, which is not a known defensive aggregator.

Verdict

Operating-company assertion

The patent originates from and remains within the Nokia corporate structure, with transfers reflecting internal restructuring rather than external sales. The current assignee, Nokia Technologies Oy, is an operating company engaged in patent licensing and development. While there is pending litigation, it appears to be an assertion by an operating company.

USPTO Assignment Center Search for US9036701B2

Here is an analysis of the most relevant prior art for US patent 9036701, based on the patent's own citations. The claims of US9036701 focus on a method and apparatus for complexity-balanced entropy coding, involving categorizing syntax elements based on a frequency of occurrence threshold. Specifically, Claim 1 states:

• Syntax elements with frequency > threshold are categorized into the first category and subjected to context updating during entropy coding.
• Syntax elements with frequency < threshold are categorized into the second category and bypass context updating during entropy coding.

I will now review each patent citation from US9036701, providing the requested information and an assessment of its potential relevance to Claim 1.

Prior Art Analysis for US9036701

1. US20020131506A1

• Full Citation: US20020131506A1, Kerofsky Louis J., "Entropy coding with adaptive syntax"
• Publication/Filing Date: Priority date: 2001-03-16; Publication date: 2002-09-19
• Brief Description: This patent application describes entropy coding methods that adapt to the syntax of the encoded data. It focuses on adaptive entropy coding, which can involve selecting different coding methods or contexts based on the type of syntax element or its history.
• Potential Anticipation (35 U.S.C. § 102): This reference generally teaches adaptive entropy coding based on syntax. It could potentially anticipate the broad concept of treating different syntax elements differently for entropy coding, which is a foundational aspect of US9036701. However, without details on explicit categorization by frequency of occurrence and the specific differential treatment of "context updating" versus "bypassing context updating" as defined in US9036701's Claim 1, it is unlikely to fully anticipate all elements of Claim 1.

2. US20090141806A1

• Full Citation: US20090141806A1, Fraunhofer-Gesellschaft Zur Foerderung Der Angewandten Forschung E.V., "Video frame encoding and decoding"
• Publication/Filing Date: Priority date: 2004-01-30; Publication date: 2009-06-04
• Brief Description: This publication relates to video encoding and decoding, particularly concerning efficient coding methods for video frames. It generally covers aspects of improving compression efficiency in video codecs.
• Potential Anticipation (35 U.S.C. § 102): This citation, with its general title, is too broad to specifically anticipate the detailed entropy coding method of Claim 1 of US9036701, which specifies categorization based on frequency and differential context updating. It likely serves as general background art for video coding.

3. US20050179572A1

• Full Citation: US20050179572A1, Lsi Logic Corporation, "Method for selection of contexts for arithmetic coding of reference picture and motion vector residual bitstream syntax elements"
• Publication/Filing Date: Priority date: 2004-02-09; Publication date: 2005-08-18
• Brief Description: This patent application discloses methods for selecting contexts for arithmetic coding, specifically for syntax elements like reference picture and motion vector residuals in a bitstream. It focuses on improving the efficiency of context-adaptive arithmetic coding.
• Potential Anticipation (35 U.S.C. § 102): This reference is highly relevant as it explicitly deals with "selection of contexts for arithmetic coding" for "syntax elements." This directly relates to the "context update" aspect of Claim 1 of US9036701. If it teaches varying context selection/adaptation based on characteristics that implicitly or explicitly relate to frequency of occurrence, or a mechanism to bypass context updates for certain elements, it could potentially anticipate some or all aspects of Claim 1, particularly the differential treatment of syntax elements in context-adaptive coding.

4. CA2643705A1

• Full Citation: CA2643705A1, Qualcomm Incorporated, "Methods and systems for refinement coefficient coding in video compression"
• Publication/Filing Date: Priority date: 2006-03-27; Publication date: 2007-10-04
• Brief Description: This patent describes methods and systems for coding refinement coefficients in video compression. Refinement coefficients are typically residual data after initial prediction and quantization, and their efficient coding is important for overall compression.
• Potential Anticipation (35 U.S.C. § 102): While dealing with coding coefficients, this reference does not appear to directly address the specific categorization of syntax elements based on frequency of occurrence and the differential application of context updating versus bypassing context updating as defined in Claim 1 of US9036701. It likely represents more general art for efficient coefficient coding within video compression.

5. WO2008053755A2

• Full Citation: WO2008053755A2, Canon Kabushiki Kaisha, "Entropy coding apparatus"
• Publication/Filing Date: Priority date: 2006-10-31; Publication date: 2008-05-08
• Brief Description: This international publication describes an entropy coding apparatus. The title suggests a general apparatus for entropy coding, which is a core component of video compression.
• Potential Anticipation (35 U.S.C. § 102): Without more specific details from the abstract or claims of this document, it's difficult to ascertain its direct relevance to the precise method of Claim 1 of US9036701. It likely covers general aspects of entropy coding systems.

6. US8213499B2 (and its application US20080276078A1)

• Full Citation: US8213499B2, General Instrument Corporation, "Method and apparatus for context address generation for motion vectors and coefficients"
• Publication/Filing Date: Priority date: 2007-04-04; Publication date: 2012-07-03 (for B2); Publication date: 2008-11-06 (for A1)
• Brief Description: This patent (and its application) focuses on generating context addresses for motion vectors and coefficients in video coding. This is crucial for context-adaptive entropy coding techniques like CABAC, where the context determines the probability model used for coding.
• Potential Anticipation (35 U.S.C. § 102): This reference is highly relevant to the "context update" aspect of Claim 1 of US9036701, as it deals with context address generation for different syntax elements (motion vectors and coefficients). If it describes any mechanism for selecting or bypassing context updates based on specific criteria (e.g., implicitly or explicitly related to frequency), it could potentially anticipate parts of Claim 1, particularly concerning the adaptive handling of contexts for different syntax elements.

7. US20090273491A1

• Full Citation: US20090273491A1, Hiroaki Sakaguchi, "Arithmetic decoding device"
• Publication/Filing Date: Priority date: 2008-04-30; Publication date: 2009-11-05
• Brief Description: This patent application describes an arithmetic decoding device. Arithmetic decoding is a form of entropy decoding, often paired with context adaptation.
• Potential Anticipation (35 U.S.C. § 102): As a general arithmetic decoding device, this patent would be considered background art for the decoding side of entropy coding. Without more specific details on how it handles syntax element categorization or differential context updating/bypassing during decoding, it is unlikely to directly anticipate Claim 1 of US9036701.

8. US7714754B2

• Full Citation: US7714754B2, Vixs Systems, Inc., "Entropy decoder with pipelined processing and methods for use therewith"
• Publication/Filing Date: Priority date: 2008-07-14; Publication date: 2010-05-11
• Brief Description: This patent describes an entropy decoder designed for pipelined processing, aiming for high throughput in decoding. Pipelining can improve performance for computationally intensive tasks like entropy decoding.
• Potential Anticipation (35 U.S.C. § 102): While dealing with an entropy decoder and its efficiency, the focus on "pipelined processing" does not directly align with the specific categorization and differential context updating/bypassing method of Claim 1 of US9036701. It is more relevant to the architectural implementation for speed rather than the coding logic for complexity balancing based on symbol frequency.

9. US20110001643A1 (and its granted patent US8294603B2)

• Full Citation: US20110001643A1, Massachusetts Institute Of Technology, "System and method for providing high throughput entropy coding using syntax element partitioning"
• Publication/Filing Date: Priority date: 2009-06-30; Publication date: 2011-01-06 (for A1); Publication date: 2012-10-23 (for B2)
• Brief Description: This patent (and its granted version) explicitly describes "syntax element partitioning" for "high throughput entropy coding." Partitioning syntax elements implies categorization, which is a key step in US9036701. The goal of "high throughput" could lead to simplified coding paths for some elements.
• Potential Anticipation (35 U.S.C. § 102): This reference is highly relevant because it uses "syntax element partitioning," which is analogous to "categorizing a plurality of syntax elements" in Claim 1 of US9036701. If the partitioning is based on frequency of occurrence (or an equivalent that leads to similar processing paths) and leads to differential treatment where some elements undergo context updating while others bypass it, it could potentially anticipate many aspects of Claim 1. The concept of "high throughput" could motivate simplifying coding for frequently occurring elements, potentially involving bypassing context updates.

10. WO2011075071A1

• Full Citation: WO2011075071A1, Telefonaktiebolaget Lm Ericsson (Publ), "Method and arrangement for video coding"
• Publication/Filing Date: Priority date: 2009-12-17; Publication date: 2011-06-23
• Brief Description: This international publication describes a method and arrangement for video coding. As a video coding patent, it broadly relates to the field but may not specifically detail the entropy coding method of US9036701.
• Potential Anticipation (35 U.S.C. § 102): Similar to US20090141806A1, this is a broad video coding patent. It is unlikely to specifically anticipate the detailed entropy coding method of Claim 1 of US9036701 without further information indicating explicit categorization by frequency and differential context updating/bypassing.

11. US20120014433A1

• Full Citation: US20120014433A1, Qualcomm Incorporated, "Entropy coding of bins across bin groups using variable length codewords"
• Publication/Filing Date: Priority date: 2010-07-15; Publication date: 2012-01-19
• Brief Description: This patent application focuses on entropy coding of bins, specifically across bin groups, utilizing variable length codewords. This implies methods for efficient coding of binary symbols that make up the representation of syntax elements.
• Potential Anticipation (35 U.S.C. § 102): This reference deals with entropy coding of "bins" and "bin groups," which is a granular level of coding relevant to context-adaptive binary arithmetic coding (CABAC), a method mentioned in US9036701. If it teaches grouping bins/syntax elements in a way that relates to frequency of occurrence and then applying differential coding (e.g., bypassing context updates for certain groups to use variable length codewords), it could potentially anticipate elements of Claim 1. The priority date (2010-07-15) is very close to US9036701's priority date (2010-07-28), suggesting it might be very relevant contemporary art.

Summary of Most Relevant Prior Art:

Based on the titles and general understanding, the most relevant prior art documents for US9036701, particularly concerning Claim 1, appear to be:

• US20050179572A1 (Lsi Logic Corporation): "Method for selection of contexts for arithmetic coding of reference picture and motion vector residual bitstream syntax elements." This directly addresses context selection for arithmetic coding of syntax elements.
• US8213499B2 / US20080276078A1 (General Instrument Corporation): "Method and apparatus for context address generation for motion vectors and coefficients." Also highly relevant to the context management in entropy coding of various syntax elements.
• US8294603B2 / US20110001643A1 (Massachusetts Institute Of Technology): "System and method for providing high throughput entropy coding using syntax element partitioning." The explicit mention of "syntax element partitioning" is a strong indicator of relevance to the categorization step in Claim 1.
• US20120014433A1 (Qualcomm Incorporated): "Entropy coding of bins across bin groups using variable length codewords." Given its close priority date and focus on bin coding and grouping, it could potentially include elements related to differential coding based on characteristics like frequency.

These patents broadly cover aspects of adaptive entropy coding, context management, and partitioning of syntax elements, which form the core concepts of US9036701's Claim 1. A full anticipation analysis would require a detailed comparison of the claims of US9036701 against the complete disclosures of these cited prior art documents.

Obviousness Analysis of US Patent 9036701 under 35 U.S.C. § 103

US Patent 9036701 (hereinafter '701 patent) claims a method and apparatus for providing complexity-balanced entropy coding in video content. The core invention, as defined by Claim 1, involves categorizing syntax elements based on their frequency of occurrence and applying different entropy coding techniques (with or without context updating) to these categories.

Specifically, Claim 1 of the '701 patent recites:
"1. A method comprising:
determining a frequency of occurrence threshold based on an expected frequency of occurrence of syntax elements in a bit stream;
categorizing a plurality of syntax elements of video content into first and second categories based on the frequency of occurrence threshold, wherein syntax elements which occur greater than the frequency of occurrence threshold are categorized into the first category and syntax elements which occur less than the frequency of occurrence are categorized into the second category;
entropy coding symbols that correspond to the first category of syntax elements and that have been subjected to a context update; and
entropy coding symbols that correspond to the second category of syntax elements and that have bypassed context updating."

A person having ordinary skill in the art (PHOSITA) in video coding at the time of the invention (priority date 2010-07-28) would have been familiar with the H.264/AVC video coding standard and its associated entropy coding schemes, Context Adaptive Variable Length Coding (CAVLC) and Context Adaptive Binary Arithmetic Coding (CABAC). The '701 patent itself acknowledges that H.264/AVC defines coding tools with different computational requirements in different profiles, with some supporting only CAVLC and others supporting CABAC, and that "computational requirements of the CABAC method increase substantially as a function of the utilized bitrate" particularly for DCT transform coefficients. This background identifies a known problem in the art: balancing coding efficiency (achieved by complex methods like CABAC) with computational complexity.

The combination of the following prior art references, along with the common general knowledge in the field, would render Claim 1 of the '701 patent obvious:

1. Marpe et al., "Context-Based Adaptive Binary Arithmetic Coding in the H.264/AVC Video Compression Standard" (2003): This non-patent literature is a foundational text describing CABAC, a key entropy coding method in H.264/AVC. It teaches the use of context models combined with adaptive binary arithmetic coding to achieve high coding efficiency and redundancy reduction. This directly discloses the concept of "entropy coding symbols... subjected to a context update," which is applied to the first category in Claim 1. Marpe et al. also acknowledges that the "computational requirements of CABAC may be still too high given today's silicon technology" and that H.264/AVC offers a baseline entropy coding method (CAVLC) with "reduced coding efficiency and complexity level compared to CABAC" for certain syntax elements, such as residual data. This implicitly teaches the existence and use of lower-complexity entropy coding methods that may involve less or no context adaptation.

2. Vivienne et al., "A High Throughput CABAC Algorithm Using Syntax Element Partitioning" (2009): This paper explicitly addresses the throughput bottleneck of CABAC in video decoding. It proposes a new CABAC algorithm where "binary symbols are grouped by syntax elements and assigned to different partitions which can be decoded in parallel". While focused on parallel processing, this reference clearly teaches the concept of categorizing or partitioning syntax elements and applying different processing (in this case, parallel decoding) based on these groupings. The paper also mentions an "adaptive binary symbol allocation scheme" that recognizes that the "distribution of binary symbols changes with quantization", demonstrating an awareness of varying symbol statistics (i.e., frequency of occurrence) in video coding.

Motivation for Combination:

A PHOSITA, faced with the recognized problem of high computational complexity associated with CABAC, particularly at high bitrates for frequently occurring data like transform coefficients (as highlighted by the '701 patent's background and Marpe et al.), would be motivated to optimize the balance between coding efficiency and complexity.

1. Categorization based on Frequency: The recognition that different syntax elements have varying statistical properties (as hinted by Vivienne et al.'s "adaptive binary symbol allocation scheme" and generally understood in adaptive coding) would motivate a PHOSITA to treat these elements differently. A "frequency of occurrence threshold" (as in Claim 1) is a straightforward and obvious statistical metric to use for such categorization, as it directly relates to how often a symbol contributes to both data size and processing load.

   • The idea of partitioning or grouping syntax elements (Vivienne et al.) provides the structural basis for this categorization.
   • The determination of a threshold is a routine engineering step when implementing a decision rule based on a quantifiable characteristic like frequency.

2. Differential Entropy Coding:

   • For syntax elements that occur greater than the frequency of occurrence threshold (first category in Claim 1), a PHOSITA would naturally choose the most efficient coding method available. Given Marpe et al.'s teaching of CABAC and its high efficiency due to context adaptation, applying "entropy coding symbols... subjected to a context update" to these high-frequency elements would be an obvious choice to maximize compression where it matters most.
   • For syntax elements that occur less than the frequency of occurrence threshold (second category in Claim 1), the computational overhead of full context adaptation might not be justified due to their rarity, or the benefit to coding efficiency might be minimal. A PHOSITA, aware of the complexity concerns with CABAC and the existence of simpler coding methods in H.264/AVC (e.g., CAVLC, or inherent bypass modes within arithmetic coders as described in the '701 patent), would be motivated to "bypass context updating" for these less frequent symbols to reduce overall computational complexity. The patent itself alludes to "static fifty percent bin probabilities" or a "bypass coding mode for a CABAC engine" as a known simplification.

By combining the teachings of Marpe et al. (for context-adaptive arithmetic coding), Vivienne et al. (for syntax element partitioning/grouping and adaptive allocation based on statistics), and the general knowledge within H.264/AVC of balancing complexity and efficiency through different coding tools, a PHOSITA would find it obvious to categorize syntax elements based on frequency and selectively apply context-adaptive or context-bypassed entropy coding to achieve a "complexity balanced" system as described in Claim 1. The motivation is clear: to mitigate the computational bottlenecks of complex entropy coding while preserving efficiency for the most significant data.