HDCP Repeater KSV Capacity Detection
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Solution Overview
Problem
HDCP sources often fail to transmit protected content to downstream sinks when they exceed the number of Key Selection Vectors (KSVs) they can support, leading to unexpected interruptions in video transmission without clear indication to the user.
Innovation Solution
A method and system that determine the maximum number of KSVs an HDCP source can support by iteratively transmitting sets of KSVs, checking for failure modes, and adjusting the number until the difference between the lowest and highest supported KSVs is one, ensuring stable encrypted video transmission and storing this maximum for future reference.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the HDCP source is configured to support a large number of downstream KSVs (up to 127), then the system should be able to handle more downstream sinks, but in practice the source enters failure mode and stops transmitting content to all sinks
Solution Approach 1:
The repeater performs preliminary detection of the source's actual KSV support capacity before content transmission begins. By sending test KSVs and monitoring for failure mode entry, the system pre-determines the maximum supported KSV count, preventing subsequent transmission failures
Solution Approach 2:
The system implements feedback by monitoring whether the source enters failure mode when receiving KSVs. This feedback information is used to adjust the number of KSVs sent to the source, ensuring it remains within the source's supported capacity and preventing transmission interruptions
2Adaptability or versatility
If the HDCP source is configured to support many KSVs, then more sinks can be connected, but the source may enter failure mode causing content transmission to stop for all sinks
Solution Approach 1:
The repeater acts as an intermediary between the source and sinks, managing KSV distribution and shielding users from the complexity of source capacity limitations. It detects source support capacity and intelligently routes KSVs, making the system easier to operate without requiring users to understand or diagnose KSV-related failures
3Device complexity
If the HDCP source supports fewer than the specification maximum of 127 KSVs, then the source can be simpler and more reliable for its supported capacity, but the system cannot utilize the full potential of downstream sinks
Solution Approach 1:
The system dynamically adapts to the source's actual KSV support capacity rather than using a fixed configuration. The repeater adjusts the number of KSVs sent based on real-time feedback from the source, allowing the system to fully utilize available capacity without requiring complex pre-configuration or over-provisioning
Data Source
AI summary
Presented is a method for determining the maximum number of key selection vectors (KSVs) supported by an HDCP source. The method includes transmitting a number of KSVs to the HDCP source, determining whether the HDCP source has entered a failure mode in response to the transmitted number of KSVs, increasing or decreasing the number of KSVs in response to the HDCP source not entering or entering the failure mode, transmitting the increased or decreased number of KSVs to the HDCP source, determining whether the HDCP source has entered the failure mode in response to the transmitted increased or decreased number of KSVs, and repeating the increasing, decreasing, and determining steps until the difference between a lowest number of transmitted KSVs resulting in the HDCP source entering the failure mode and a highest number of transmitted KSVs resulting in the HDCP source not entering the failure mode is one.