DCT

2:22-cv-00866

MZ Audio Sciences LLC v. Sony Group Corp Japan

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Key Events
Complaint

I. Executive Summary and Procedural Information

  • Parties & Counsel:
  • Case Identification: 2:22-cv-00866, C.D. Cal., 02/08/2022
  • Venue Allegations: Plaintiff alleges venue is proper because Defendants have committed acts of infringement and maintain regular and established places of business in the Central District of California, including corporate headquarters and other offices.
  • Core Dispute: Plaintiff alleges that Defendants’ Blu-ray players and PlayStation consoles, which incorporate Cinavia audio watermarking technology for content protection, infringe a patent related to embedding and extracting data by manipulating the phase of audio signals.
  • Technical Context: The technology at issue is steganographic audio watermarking, a form of digital rights management (DRM) used to embed inaudible data in audio tracks to control the use and prevent the piracy of content like films and music.
  • Key Procedural History: The complaint notes that Plaintiff previously filed a similar lawsuit against Sony in the District of Delaware, which was voluntarily dismissed after Defendants contested venue. The complaint also provides extensive background on the failure of prior art watermarking technologies, such as those from Verance and Digimarc, which were found to be vulnerable to removal, particularly in the context of the Secure Digital Music Initiative (SDMI) in the early 2000s.

Case Timeline

Date Event
2003-06-19 ’961 Patent Priority Date
2006-06-20 First Blu-ray Disc titles released (5 of 6 by Sony)
2006-11-01 Sony PlayStation 3, including a Blu-ray player, released
2007-10-30 U.S. Patent No. 7,289,961 Issued
2009-07-01 Cinavia introduced as an optional component in Blu-ray players
2009-11-01 Sony releases PS3 firmware update v3.10 including Cinavia protection
2012-01-01 Cinavia becomes mandatory for all new Blu-ray player certifications
2021-11-24 Prior lawsuit filed by Plaintiff against Sony in D. Del.
2022-02-08 Complaint Filing Date

II. Technology and Patent(s)-in-Suit Analysis

U.S. Patent No. 7,289,961 - Data Hiding Via Phase Manipulation of Audio Signals

  • Patent Identification: U.S. Patent No. 7,289,961, Data Hiding Via Phase Manipulation of Audio Signals, issued October 30, 2007.

The Invention Explained

  • Problem Addressed: The patent’s background section describes prior art watermarking technologies as being vulnerable to hacking and removal, particularly through "general signal process analysis" that could discover the watermark's key (’961 Patent, col. 2:63-col. 3:3). The complaint highlights the failure of the Verance technology selected by the SDMI, which was publicly defeated in a "hackers challenge" (Compl. ¶¶ 35-38).
  • The Patented Solution: The invention proposes embedding data by manipulating the phase of an audio signal's frequency components, rather than its amplitude (’961 Patent, Abstract). It leverages the observation that the phase of an audio spectrum is "apparently random" to the human ear, creating an opportunity to substitute this randomness with a pseudo-random sequence containing hidden data (’961 Patent, col. 4:22-26). One specific method involves identifying a fundamental tone and its overtones, and then "quantizing" the phase difference between them to represent binary data (e.g., a '1' or '0') (’961 Patent, col. 5:40-54; Fig. 4).
  • Technical Importance: This phase-based manipulation was designed to create a watermark that is aurally transparent, undetectable without a "key," and robust enough to survive both digital signal processing attacks and digital-to-analog-to-digital conversions, which were significant weaknesses in prior systems (’961 Patent, col. 4:31-37).

Key Claims at a Glance

  • The complaint asserts independent method Claim 1 and independent device Claim 9 (Compl. ¶¶ 100, 124).
  • Independent Claim 1 (Method): The key elements are (a) dividing an audio signal into time frames and frequency components; (b) selecting at least two frequency components, specifically a "fundamental tone and at least one overtone"; and (c) "altering a phase" by "quantizing a phase difference of the at least one overtone relative to the fundamental tone" to embed data.
  • Independent Claim 9 (Device): The key elements include an input, an output, and a processor configured to (a) divide the signal into frames and components; (b) select at least two components, specifically a "fundamental tone and at least one overtone"; (c) "determining a phase shift" that was applied in accordance with embedded data; and (d) "extracting the embedded data" from that phase shift.
  • The complaint reserves the right to assert additional claims (Compl. ¶100).

III. The Accused Instrumentality

Product Identification

The accused instrumentalities are Sony's "Infringing Players," which include a range of Blu-ray Disc players and PlayStation consoles (PS3, PS4, PS5) that incorporate Cinavia watermark detection technology (Compl. ¶¶ 101-102). The complaint also accuses the methods used by Sony Pictures Entertainment (SPE) and other Sony entities to embed the Cinavia watermark into the audio tracks of their media content (Compl. ¶126).

Functionality and Market Context

The accused players utilize Cinavia "Detector" technology to analyze the audio signal of media content, identify the presence of the Cinavia watermark, and block playback if the media is determined to be an unauthorized copy (Compl. ¶¶ 82, 107). The complaint presents a screenshot from a Sony player's operating instructions, which includes a "Cinavia Notice" stating that the technology is used "to limit the use of unauthorized copies" (Compl. ¶109). The complaint alleges Sony was a primary advocate for and early adopter of the Cinavia standard to protect its substantial investments in both content creation (e.g., movies) and content delivery hardware (e.g., the Blu-ray format) (Compl. ¶¶ 83-86).

IV. Analysis of Infringement Allegations

U.S. Patent No. 7,289,961 Infringement Allegations

The complaint alleges that Sony's devices infringe device Claim 9 and that Sony's content-creation entities infringe method Claim 1. The infringement theory for both claims relies on the same underlying technical analysis of how the Cinavia system allegedly works. The complaint provides waveform and spectrum analysis graphs, such as the "Right channel spectrum" graph, to visually support its theory that Cinavia operates by creating and detecting specific phase shifts between a fundamental tone and its harmonics (Compl. ¶117). A summary of the allegations against device Claim 9 is presented below.

Claim Element (from Independent Claim 9) Alleged Infringing Functionality Complaint Citation Patent Citation
A device for extracting embedded data from an audio signal, the device comprising: an input for receiving the audio signal; Sony's Blu-ray players and PlayStation consoles receive audio signals from Blu-ray Discs, DVDs, and streaming media. The complaint includes screenshots of representative players (Compl. ¶108) and lists of supported disc and file formats (Compl. ¶¶ 111-112). ¶108, ¶111-112 col. 10:1-3
a processor, in communication with the input, for: (a) dividing the audio signal into a plurality of time frames and, in each time frame, a plurality of frequency components; The Cinavia watermark is allegedly repeated throughout the audio, allowing the device's processor to detect it by analyzing short segments, or time frames, of the signal. ¶115 col. 9:36-39
(b) in each of at least some of the plurality of time frames, selecting at least two of the plurality of frequency components; ... wherein the processor preforms step (b) by selecting a fundamental tone and at least one overtone. The processor allegedly detects the watermark by analyzing the relationship between a fundamental frequency and its harmonics. A provided graph purports to show the identification of a "Fundamental tone at 98.77 Hz" and its harmonics in a test signal (Compl. ¶117). ¶117-118 col. 10:26-29
(c) determining a phase shift which has been applied to at least one of the plurality of frequency components in accordance with the embedded data; The complaint presents a comparative waveform graph allegedly showing a phase change of approximately π radians in a harmonic of a watermarked audio track ("Cin") relative to an original track ("Orig"), which the processor allegedly determines. ¶116, ¶118 col. 10:17-21
and (d) from the phase shift determined in step (c), extracting the embedded data; and an output for outputting the embedded data... The processor allegedly extracts the data (e.g., a "1" for a π radian shift) and outputs this information to the system, which then applies content control policies such as interrupting playback. The "Cinavia Notice" from a user manual confirms this function (Compl. ¶109). ¶119-120 col. 10:22-25
  • Identified Points of Contention:
    • Technical Questions: A central question will be factual: does the accused Cinavia detector technology actually operate by "selecting a fundamental tone and at least one overtone" and "determining a phase shift" between them, as the patent requires and the complaint's technical analysis alleges? The defense may argue that Cinavia uses a different, non-infringing algorithm (e.g., correlation against a known signal template) to detect the watermark, and that the phase shifts observed by the plaintiff are merely an artifact of that different process, not the direct mechanism of detection.
    • Scope Questions: Does the Cinavia system's function of detecting a binary copy-protection trigger (e.g., authorized/unauthorized) fall within the scope of "extracting the embedded data" as that term is used in the patent? The defense may contend that the patent describes a more general-purpose system for embedding and retrieving arbitrary data, and that Cinavia's highly specific use for copy-flag detection is technically distinct and outside the claimed scope.

V. Key Claim Terms for Construction

  • The Term: "quantizing a phase difference" (Claim 1) / "determining a phase shift" (Claim 9)

    • Context and Importance: These terms define the core technical action of the invention. The outcome of the case may depend on whether the operation of the accused Cinavia technology is found to meet this definition. Practitioners may focus on this term because it distinguishes the patented method from other potential watermarking techniques.
    • Intrinsic Evidence for a Broader Interpretation: The specification describes the general concept of modulating the phases of overtones to create a composite waveform different from the original, which could support a construction covering any method that uses discrete phase states to encode information (’961 Patent, col. 4:17-21).
    • Intrinsic Evidence for a Narrower Interpretation: The detailed description provides a specific mathematical formula for quantization: "ΔΦ=π/2^n" (’961 Patent, col. 6:5-12). A defendant could argue this formula limits the scope of "quantizing" to this specific implementation, rather than any method of creating phase shifts.

  • The Term: "selecting a fundamental tone and at least one overtone" (Claims 1 & 9)

    • Context and Importance: This limitation anchors the phase manipulation to a specific, well-defined acoustic structure. Infringement depends on whether the accused devices are proven to perform this specific selection process.
    • Intrinsic Evidence for a Broader Interpretation: The specification presents this as a preferred approach, noting that naturally occurring audio like music and voice "contain a fundamental frequency and a spectrum of overtones," making it a useful channel for data transmission (’961 Patent, col. 4:15-21). This could suggest it is an exemplary, not exclusive, method.
    • Intrinsic Evidence for a Narrower Interpretation: The description of the preferred "QIM" embodiment is explicitly based on this structure, explaining that the process involves selecting an "apparent fundamental tone and its series of overtones" and then quantizing the phase of "two of the overtones" (’961 Patent, col. 5:40-52). This detailed embodiment could be used to argue the claim is limited to processes that explicitly identify and operate on this harmonic structure.

VI. Other Allegations

  • Indirect Infringement: The complaint alleges that Sony induces infringement of method Claim 1 by third-party content creators (e.g., other movie studios). The theory is that by manufacturing and promoting a fleet of Cinavia-enabled players, Sony encourages these third parties to embed the Cinavia watermark in their own content to take advantage of the copy protection ecosystem Sony helped establish (Compl. ¶¶ 140-143).
  • Willful Infringement: The willfulness allegation is based on alleged pre-suit and post-suit knowledge. Plaintiff alleges Sony had pre-suit knowledge of the ’961 Patent through its routine monitoring of anti-piracy internet forums where the patent was discussed in relation to Cinavia, and through the "revolving door" of executives between Sony and Verance (the developer of Cinavia) (Compl. ¶¶ 93-97). Knowledge is also alleged based on the prior, dismissed lawsuit filed in Delaware (Compl. ¶98).

VII. Analyst’s Conclusion: Key Questions for the Case

  • A key evidentiary question will be one of technical operation: Does discovery and expert analysis confirm that the Cinavia system functions by performing the specific steps of selecting a fundamental tone and its overtones and then determining a quantized phase shift between them, as required by the claims? Or will evidence show it uses a different, non-infringing technical method to detect the watermark?
  • A core issue will be one of definitional scope: Can the patent’s claims, which describe a system for embedding and "extracting... data," be construed to cover the accused Cinavia system, which performs the more specific function of detecting a binary copy-protection flag to enable or disable playback?
  • An important factual question for willfulness and inducement will be the extent of Sony's knowledge: What evidence exists to demonstrate that Sony knew of the ’961 Patent and its alleged relevance to the Cinavia technology prior to the lawsuit, beyond the circumstantial allegations of monitoring internet forums and employee overlap?