US 8542705

US patent 8542705, titled "Key frame detection and synchronization," was filed on January 23, 2007, and issued on September 24, 2013. The inventors are Kay Johansson and Kent Karlsson. The original assignee was MobiTv Inc, with the current assignee listed as Adeia Media Holdings Inc.

Abstract:
The patent describes mechanisms for a streaming server to efficiently deliver frames of a media stream to a client device. The streaming server receives multiple media streams and identifies key frames within them. Upon receiving a connection request from a client device, the server selects and provides a key frame to the client. This ensures that the client device does not have to drop or inaccurately display any predictive frames before beginning to play the media stream.

Plain-Language Overview of Independent Claims:

• Claim 1 (Method): This claim outlines a process for a streaming server to manage and deliver media streams efficiently. The server receives at least two media streams (e.g., different video channels) and stores them in separate buffers, which are organized according to "Groups of Pictures" (GOPs). The server determines which frames are "key frames" by, for example, identifying the size of a GOP and then marking every Nth frame following an initial key frame as a subsequent key frame. When a user on a client device requests to switch from one media stream (channel) to another, the server identifies the earliest available key frame in the new media stream. This key frame is then immediately sent to the client, ensuring that no predictive frames (which cannot be displayed on their own) are sent at the start of the channel change.
• Claim 8 (System): This claim describes a physical system, specifically a streaming server, designed to perform the method of Claim 1. The system includes an interface for receiving multiple media streams and a processor. The server maintains buffers for these streams, allocating them on a per-GOP basis. The processor is configured to identify key frames within these streams, using methods like determining the GOP size (N) to find subsequent key frames. When the server receives a channel change request from a client, the processor identifies the next available key frame for the newly requested media stream. This system is designed to provide that identified key frame to the client without transmitting any predictive frames at the outset of the channel change request.
• Claim 15 (Non-Transitory Computer Readable Medium): This claim covers a computer program product stored on a non-transitory computer-readable medium (such as a hard drive or flash memory). This computer code, when executed, causes a streaming server to perform the method steps detailed in Claim 1. This includes receiving and buffering media streams on a per-GOP basis, identifying key frames (partially by using GOP size N), receiving channel change requests, identifying the next available key frame for the requested channel, and providing this key frame to the client without sending predictive frames at the beginning of the channel change.

Legal Status and Dockets:
The patent is currently active and is expected to expire on November 8, 2028. The Google Patents information indicates ongoing litigation: a PTAB case (IPR2026-00052) filed by Unified Patents, which has reached "Procedural Termination," and a US case filed in the Delaware District Court (1:24-cv-01231). There is also a record of the first worldwide family litigation being filed. The general CAFC docket searches conducted for 2026 did not yield specific details related to US8542705, but rather provided broader summaries of Federal Circuit activities.