Interleaved Watermarking for Broadcast Video Capacity
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Solution Overview
Problem
Existing interleaved watermarking systems for broadcast video have limitations in embedding unique identifiers for end-user devices, particularly in terms of capacity and robustness, due to the use of limited secondary streams which restrict the number of payload bits that can be embedded per cryptoperiod, affecting detection speed and anti-collusion capabilities.
Innovation Solution
The system generates multiple secondary video streams from sections of a primary video stream, groups them to allow selection and encryption with different control words per cryptoperiod, and uses a secure processor in end-user devices to decrypt and interleave these streams, embedding identification data in the composited video stream, thereby increasing watermark capacity and robustness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If multiple secondary video streams are generated and grouped with different control words, then watermark capacity and robustness are improved, but device complexity and processing requirements increase
Solution Approach 1:
The video stream is segmented into multiple secondary streams, each carrying portions of the watermark payload. The watermark data is divided across different cryptoperiods and secondary streams, with each stream encrypted using different control words. This segmentation allows the system to embed more payload bits while distributing the complexity across manageable segments rather than requiring one complex stream.
Solution Approach 2:
The system uses periodic cryptoperiods to manage control words and secondary stream selection. Each cryptoperiod contains a specific number of payload bits that are embedded in a structured manner across the secondary streams. This periodic structure allows the end-user device to systematically process and combine streams while maintaining security through rotating control words, thereby improving robustness without proportionally increasing complexity.
2Productivity
If more payload bits are embedded per cryptoperiod, then detection speed is improved, but bandwidth efficiency decreases
Solution Approach 1:
The system embeds watermark data in an additional dimension by using multiple secondary streams with different control words within the same cryptoperiod. Instead of embedding all payload bits in a single stream, the data is distributed across multiple streams that are selectively combined at the end-user device. This dimensional approach allows more payload bits to be embedded without proportionally increasing the bandwidth consumption of any single stream.
Solution Approach 2:
The secondary streams serve multiple functions: they carry both video content and watermark payload bits, and different streams can be selectively activated based on the control word. This multi-functionality allows the system to embed more watermark data while reusing the same bandwidth infrastructure, as not all secondary streams need to be transmitted simultaneously with full bandwidth allocation.
3Reliability
If secondary streams are encrypted with different control words per cryptoperiod, then security is improved, but processing time and computational load increase
Solution Approach 1:
The control words for multiple secondary streams are generated and prepared in advance within each cryptoperiod structure. The entitlement control messages contain the necessary information for the end-user device to generate the correct control words before decryption is needed. This preliminary preparation reduces real-time processing time, as the device can systematically retrieve and apply pre-computed control words rather than performing complex key derivation during playback.
Data Source
AI summary
In one embodiment, a system includes a Headend apparatus including a watermark processor to generate secondary video streams from sections of a primary video stream, group the secondary video streams in groups of at least two secondary video streams, the secondary video streams including units of data for use in watermarking across cryptoperiods in an end-user device which selects one secondary video stream in each group for rendering as part of a composited video stream in order to embed units of data of an identification in the composited video stream, wherein in each cryptoperiod, the watermark processor is operative to generate different groups of the secondary video streams from different non-overlapping portions of the primary video stream, and an encryption processor to generate control words, encrypt each secondary video stream with a different control word, and change the control word of each secondary video stream every cryptoperiod.