Content Timeline Tracker for DVR Playback Rate Changes
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Solution Overview
Problem
Existing video watermarking systems face challenges in synchronizing auxiliary content with a watermark timeline that has a non-linear mapping to real time, particularly when playback rates change due to user interactions such as trickplay functions in STB devices.
Innovation Solution
A method involving a Detector Engine to extract time-offset, VP1 payload, and CRC fields from video frames, and a Content Timeline Tracker to produce a piecewise linear approximation of the content timeline, enabling synchronization of auxiliary content with the recovered watermark timeline even under non-linear playback conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the watermark timeline is used for synchronizing auxiliary content, then synchronization is achieved under normal playback, but the synchronization becomes inaccurate when playback rate changes occur
Solution Approach 1:
The patent implements a dynamic playback rate detection mechanism that continuously monitors the actual playback rate and adjusts the timeline mapping in real-time. The system detects playback rate changes by comparing timestamps of consecutive watermarks and dynamically recalculates the timeline transformation parameters, allowing the synchronization system to adapt to varying playback conditions while maintaining accuracy
Solution Approach 2:
The system changes the parameter representation of the timeline by introducing a playback rate compensation factor that transforms the original linear watermark timeline into a corrected timeline that accounts for non-linear playback. This parameter transformation allows the auxiliary content to be synchronized accurately regardless of playback rate variations
2Measurement precision
If the system tracks playback rate changes to maintain synchronization, then accuracy is improved, but system complexity increases
Solution Approach 1:
The patent segments the timeline tracking function into distinct modular components: a watermark detection module that extracts timestamps, a playback rate calculation module that computes rate changes, and a timeline correction module that applies transformations. This segmentation allows each component to perform its specific function with high precision while keeping the overall system manageable and maintainable
Solution Approach 2:
The system introduces an intermediary playback rate compensation mechanism that acts as a mediator between the original watermark timeline and the auxiliary content playback. This intermediary layer transforms the timeline parameters without requiring fundamental changes to the existing watermarking or auxiliary content playback infrastructure, thereby achieving high tracking precision with minimal added complexity
Data Source
AI summary
A system and method for controlling a media player for replacement content, such as dynamic ad insertion. The system tracks video watermarks from a content stream, where the input content timeline is being modified by a user exercising the transport controls of a digital video recorder (DVR). A Detector Engine receives decoded video frames and extracts a time-offset field, a VP1 payload, and a Cyclic Redundance Check (CRC) field in each video frame. A Content Timeline Tracker monitors and analyzes the output of the Detector Engine to produce a piecewise linear approximation of the content timeline, wherein playback rate changes by a user in an upstream device can be tracked. This enables the playback of auxiliary content which is synchronized to a watermark timeline recovered from the received content in cases where the recovered timeline has a non-linear mapping to real time. When the estimated speed is changing due to user-controlled trick play of recorded content, estimated speed deviates from the user intended speed profile because of imperfect playback of the media player. The system includes additional filtering of estimated speed to produce a Boolean updated speed which is asserted sparsely at estimated control segment endpoints in an attempt to delineate constant slope (constant speed) control segments.