Prior art

Based on a review of the prosecution history and the face of U.S. Patent 11,677,798 B2, the following patents were cited as prior art. Below is an analysis of the most relevant references and their potential impact on the claims of the '798 patent.

Analysis of Prior Art Cited in U.S. Patent 11,677,798 B2

The core invention of the '798 patent, as defined by its independent claims, involves a client device that:

1. Requests and receives media content in sequential segments ("streamlets").
2. Monitors the time it takes to receive these streamlets.
3. Calculates a performance metric based on these receive times.
4. Uses this metric to decide whether to shift to a higher or lower bitrate stream.
5. Crucially, before shifting up to a higher quality, it determines if the higher quality stream is sustainable based on an estimate of the network's performance.

The following prior art references are evaluated against these core concepts.

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1. U.S. Patent No. 7,552,236 B2: "Adaptive streaming of multimedia data over a network"

• Full Citation: U.S. Patent 7,552,236 B2, "Adaptive streaming of multimedia data over a network," Inventors: Cherian, et al., Assignee: Microsoft Corporation.
• Publication/Filing Dates:
  • Filing Date: June 15, 2004
  • Issue Date: June 23, 2009
• Brief Description: This patent from Microsoft describes a system for adaptive streaming where a media server has multiple versions of a media file, each encoded at a different bit rate. A client device requests segments of the media and monitors network conditions, such as the rate at which data is received. Based on these conditions, the client can switch between the different bitrate streams to maintain a smooth playback experience. The client monitors its buffer level and available bandwidth to make decisions about which stream to request next.
• Potential Anticipation of Claims:
  • Claims 1, 7, 13: The '236 patent discloses the fundamental concepts of adaptive bitrate (ABR) streaming that form the basis of the '798 patent's claims. It teaches a client device requesting media segments and monitoring network conditions to switch between different quality streams (Column 4, lines 17-38). The patent describes monitoring bandwidth and making a determination to switch to a higher or lower bitrate stream. However, the '798 patent's claims include a specific limitation: "determining whether use of the higher quality stream is sustainable" before upshifting by comparing an "estimate of the higher quality stream's performance factor" with a threshold (Claim 1, Column 16, lines 52-59). While the '236 patent makes decisions based on available bandwidth, it may not explicitly disclose the specific two-step process of first considering an upshift and then performing a separate sustainability calculation based on an estimated performance factor for the higher stream. This subtle difference in the decision-making logic likely prevented a finding of direct anticipation by the examiner.

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2. U.S. Patent Application Publication No. 2002/0083157 A1: "Method and system for providing continuous streaming media"

• Full Citation: U.S. Patent Application Publication 2002/0083157 A1, "Method and system for providing continuous streaming media," Inventors: Chord-sri, et al.
• Publication/Filing Dates:
  • Filing Date: December 21, 2000
  • Publication Date: June 27, 2002
• Brief Description: This publication describes a system where a client device monitors network conditions to select an appropriate media stream from a server that offers multiple streams at different bitrates. The client measures network throughput and uses this measurement to select a stream with a bitrate that the network can support. It describes a "stream-switching decision logic" that evaluates whether to switch to a higher or lower rate stream based on measured bandwidth and buffer conditions.
• Potential Anticipation of Claims:
  • Claims 1, 7, 13: This reference discloses the core ideas of monitoring network performance (throughput) and switching between different quality streams. The logic for switching is based on comparing the measured throughput to the bitrates of the available streams (Paragraph). The key question for anticipation is whether this disclosure meets the '798 patent's specific limitation of determining if a higher quality stream is "sustainable." The '3157 publication teaches selecting a stream "whose bit rate is less than or equal to the estimated available bandwidth" (Paragraph). This is functionally very similar to the "sustainability" check in the '798 patent. However, the '798 patent claims a specific method of calculating a "performance factor" based on the time intervals between successive receive times of streamlets and then estimating that factor for the next higher quality stream. The method detailed in the '3157 publication, while achieving a similar goal, does not appear to describe this exact calculation and estimation process, thereby likely avoiding anticipation.

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3. U.S. Patent No. 6,985,947 B2: "Method and system for providing content delivery in a data transmission system"

• Full Citation: U.S. Patent 6,985,947 B2, "Method and system for providing content delivery in a data transmission system," Inventors: D'Souza, et al., Assignee: iBEAM Broadcasting Corp.
• Publication/Filing Dates:
  • Filing Date: March 24, 2000
  • Issue Date: January 10, 2006
• Brief Description: This patent focuses on a content delivery network (CDN) architecture. It describes a system for efficiently delivering streaming media by using a network of servers. It discloses techniques for monitoring network congestion and server load. A client can receive data from different servers, and the system can dynamically adjust the data source to optimize delivery. It discusses providing content at different quality levels in response to network conditions.
• Potential Anticipation of Claims:
  • Claims 1, 7, 13: The '947 patent broadly discusses adapting content delivery to network conditions. It teaches a system that can select different data rates based on feedback about the network (Column 5, lines 37-45). The focus, however, is more on the server-side infrastructure (the CDN) and less on the specific client-side decision-making algorithm claimed in the '798 patent. The '947 patent does not appear to disclose the client-side method of monitoring streamlet receive times, calculating a performance factor, and performing a specific sustainability check before upshifting, as required by the independent claims of the '798 patent. Therefore, it is unlikely to anticipate these claims.

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Summary of Prior Art Analysis

The prior art cited against US 11,677,798 B2, particularly references from Microsoft and others in the early 2000s, establishes the foundational principles of adaptive bitrate streaming. These references clearly teach the concepts of segmenting media, providing multiple bitrate versions, and having a client monitor network conditions to switch between these versions.

The novelty of the '798 patent, which allowed it to be granted over this art, appears to reside in the specific, detailed algorithm for making the upshift decision. The claimed method of monitoring time intervals between successive receive times, calculating a performance ratio r, obtaining a performance factor ρ, and then using that to estimate if a higher quality stream is sustainable before committing to the switch, was likely considered a specific, non-obvious improvement over the more general bandwidth and buffer-level monitoring taught by the prior art. The claims are not to adaptive streaming in general, but to a particular method of implementing it.