IP Law Daily, TOP STORY—Fed. Cir.: District court erred in finding Hulu’s streaming servers did not infringe data buffer patent, (May 11, 2022)

By George Basharis, J.D.

On remand, court will determine whether the method of caching streaming data by Hulu’s content servers infringed a patented method for reducing network lag using data buffers.

An intellectual property licensing company will have an opportunity to show that servers used by Hulu to stream multimedia content infringed one of its patents for improving network performance by reducing lag using data buffering. Rejecting a district court’s finding that the terms “buffer” and “cache” should be construed as separate requirements of the claimed invention, the Federal Circuit vacated the lower court’s summary judgment of non-infringement and directed the trial court to determine if components of Hulu’s servers labeled as “caches” infringed on one of the licensing company’s buffer patents (Sound View Innovations, LLC v. Hulu, LLC, May 11, 2022, Taranto, R.).

Sound View Innovations, LLC owns now-expired U.S. Patent No. 6,708,213 (the ’213 patent). The ’213 patent describes and claims methods to “improve the caching of streaming multimedia data” from a content provider over a network to a client’s computer. The methods use “helper servers” to buffer data to minimize delays in content delivery and server and network loads. Hulu is a content provider that streams multimedia content to users and employs “edge,” or “helper” servers, to minimize network latency.

In 2017, Sound View sued Hulu for infringement of the ’213 patent arguing that Hulu directed or controlled its content delivery networks to allocate a local buffer at an edge server (the claimed helper server) to cache at least a portion of a Hulu video and to download that video portion to a client while concurrently pre-fetching (i.e., retrieving) another portion of the video, in other words, buffering content to reduce lag for the end user. The ’213 patent claims to reduce lag using a claimed method of “downloading and retrieving” data.

Sound View and Hulu disputed the meaning of the ’213 patent’s downloading/retrieving claim limitation. According to Sound View, the limitation does not require that downloading data and retrieving data involve the same buffer. It could be accomplished separately. Hulu, on the other hand, argued that the claimed downloading/retrieving function employed the same buffer and moved for summary judgment of non-infringement. According to Hulu, because the ’213 patent required the downloading and retrieving functions to be performed by the same buffer—and Hulu’s helper servers did not download and retrieve streaming content to the same buffer—there could be no infringement of the ’213 patent’s “same-buffer” claim. The district court agreed with Hulu, finding the ’213 patent used the terms “buffer” and “cache” to refer to distinct physical components; therefore, the caching used by Hulu helper servers did not infringe the ’213 patent as a matter of law.

Sound View appealed, arguing that there was a factual dispute as to whether the caches used by Hulu helper servers satisfied the buffer limitation of its ’213 patent. Sound View also appealed the local court’s rulings that excluded damages evidence presented by one of its expert witnesses.

The Federal Circuit noted that although the downloading/retrieving limitation did not expressly refer to “buffers,” the patent did describe and illustrate an embodiment with only one buffer of a helper server simultaneously downloading and retrieving content data. Moreover, during the patent’s prosecution history, Sound View distinguished a prior invention claiming a method of retrieving and emptying buffers seriatim from content or helper servers by emphasizing that, unlike the prior art invention, the buffering claimed by the ’213 patent would happen concurrently. In other words, Sound View’s invention concurrently emptied and filled the buffer, while the prior art claimed a method of filling the buffer only after the buffer was empty. Consequently, the Federal Circuit affirmed the lower court’s same-buffer claim construction. However, it reversed the district court’s summary judgment of non-infringement.

The district court determined the ’213 patent described buffers and caches in different component locations, and, therefore, the cache used by Hulu servers could not satisfy the buffer limitation of Sound View’s patent. However, the Federal Circuit found problematic the district court’s reluctance to adopt an affirmative construction of what constituted a buffer, which was needed in the case because the terms “buffer” and “cache” as used in the ’213 patent were not mutually exclusive and seemed to have at least some overlap in their coverage. For example, the patent described “allocating a buffer to cache” and explaining elsewhere that a certain type of buffer operated as a type of cache. Ultimately, the Federal Circuit concluded that the term “buffer” should be given its ordinary meaning to describe “temporary storage for data being sent or received.” The Federal Circuit vacated the summary judgment of non-infringement and remanded the case to the lower court to determine if the component of Hulu’s helper servers called a “cache” performed the function of a “buffer” by temporarily storing data in transit to the end users.

Damages. The Federal Circuit found the district court did not abuse its discretion by excluding expert testimony regarding Sound View’s damages claim. Sound View proposed to have an expert witness establish the amount of a reasonable royalty if infringement was found. To determine a reasonable royalty, the expert would estimate the value of the ’213 patent to a video-streaming provider based on the improved user experience if the invention were used, including fewer occasions of stalling of the video on the user’s device. However, the expert opinion was based on a study of adaptive streaming used by mobile devices in vehicles connected to wireless networks in Australia. By contrast, Hulu’s streaming services were streamed to desktop computers or television sets via Wi-Fi or wired connections in the United States. Consequently, the expert’s use of the Australia study rendered his opinion unreliable. The district court also excluded expert testimony based on a press release concerning the optimal streaming experience. The lower court found the testimony to be unreliable because the expert witness did not himself study the report on which the press release was based

The case is No. 2021-1998.

Attorneys: Alan Kellman (Desmarais LLP) for Sound View Innovations, LLC. Brett Johnston Williamson (O'Melveny & Myers LLP) for Hulu, LLC.

Companies: Sound View Innovations, LLC; Hulu, LLC

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