Video Stream Watermarking via Frame Substitution in CDNs
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Solution Overview
Problem
Content delivery networks face challenges in identifying and disrupting pirated content, particularly when pirates source content directly from the CDN, and there is a need for effective digital watermarking techniques to verify authenticity and integrity.
Innovation Solution
A method of watermarking video streams by substituting frames with substitute frames containing watermarks, which can be tailored to the client device, causing perceptible degradation for suspect devices and minimal disruption for authorized users, using I-macroblocks to reduce processing load.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If digital watermarking is applied to identify and disrupt pirated content, then the ability to detect and trace pirated content improves, but the video quality and viewing experience deteriorate for unauthorized users
Solution Approach 1:
The patent applies local quality by inserting watermarks only at specific locations within the video stream (such as at regular intervals between keyframes) rather than uniformly throughout. This allows the watermark to be detectable for authentication while minimizing its visual impact on overall video quality. The substitute frames containing watermarks are strategically placed to maintain acceptable viewing experience while still providing effective tracking capability.
2Measurement precision
If substitute frames with watermarks are inserted into the video stream, then content tracking capability improves, but the processing load and bandwidth requirements increase
Solution Approach 1:
The patent segments the video stream into discrete frames or blocks, inserting watermarks only in specific segments rather than processing the entire video continuously. This segmentation approach allows for manageable processing complexity while maintaining effective watermark detection. The system processes only the necessary portions of the video stream where watermarks need to be embedded, reducing overall computational burden.
Solution Approach 2:
The patent uses substitute frames that copy or reference existing video frames rather than generating entirely new content. The substitute frames contain watermarks and reference adjacent frames, which reduces the processing load compared to creating completely new video content. This copying approach maintains watermark detection accuracy while minimizing the computational resources required.
3Reliability
If frequent frame substitution is used to ensure watermark visibility, then the ability to identify pirated content improves, but the disruption to authorized users' viewing experience increases
Solution Approach 1:
The patent applies partial action by inserting watermarks at specific intervals rather than continuously or excessively frequently. This partial approach ensures that watermarks are visible and detectable for reliable piracy identification, while avoiding excessive disruption to authorized users' viewing experience. The frequency and location of substitute frames are optimized to balance detection reliability with viewing quality.
Data Source
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AI summary
A method of watermarking a video stream comprising a plurality of video frames in sequence, comprising, within a content delivery network, CDN: receiving said video stream; substituting one or more frames of the video stream with one or more corresponding substitute frames, wherein each substitute frame comprises an inter-frame encoded frame including a watermark; and delivering the video stream with the substituted one or more frames to a client device.