Video Watermark Robustness via I-Frame to B-Frame Conversion
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Solution Overview
Problem
Digital watermarks embedded in video content are vulnerable to loss during compression, making it difficult to detect them, especially in moving picture contents that undergo multiple lossy compression steps, which reduces their robustness and visibility.
Innovation Solution
A method and apparatus that structurally change a video bitstream by converting I frames into B frames before embedding watermarks, enhancing the watermark's robustness and detection rate by determining optimal embedding positions and using reencoding techniques to minimize capacity increase and bit rate damage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If watermark is embedded in lossy compressed frames, then compression efficiency is improved, but watermark robustness deteriorates
Solution Approach 1:
The patent applies preliminary action by converting the frame type (I-frame to B-frame) before watermark embedding. This structural conversion prepares the frame in advance to preserve watermark signals during subsequent lossy compression, allowing the watermark to survive compression attacks while maintaining compression efficiency.
Solution Approach 2:
The patent changes the frame type parameter from I-frame to B-frame to alter the compression characteristics. This parameter change enables the watermark signal to be preserved through lossy compression by exploiting the bidirectional prediction capability of B-frames, thereby resolving the contradiction between compression efficiency and watermark robustness.
2Productivity
If multiple lossy compression steps are applied, then transmission efficiency is improved, but watermark detection capability deteriorates
Solution Approach 1:
The patent performs preliminary frame type conversion before multiple compression steps are applied. This preliminary action ensures that the watermark signal is embedded in a frame structure (B-frame) that can withstand multiple lossy compression operations, maintaining detection capability even after repeated compression cycles.
Solution Approach 2:
The patent provides beforehand cushioning by converting I-frames to B-frames, which creates a protective structure that cushions the watermark signal against the cumulative damage of multiple lossy compression steps. This preparatory measure ensures the watermark survives subsequent compression attacks.
3Reliability
If I-frame is converted to B-frame for watermark embedding, then watermark robustness is improved, but encoding complexity increases
Solution Approach 1:
The patent applies preliminary action by performing frame type conversion only when watermark embedding is required. This selective preliminary conversion minimizes the impact on overall encoding complexity while achieving the robustness benefit for watermarked content.
Solution Approach 2:
The patent changes the frame type parameter from I-frame to B-frame, which increases encoding complexity due to bidirectional prediction requirements. However, this parameter change is localized only to frames requiring watermark embedding, thereby limiting the overall complexity increase while achieving improved watermark robustness.
Data Source
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AI summary
One aspect of the present invention discloses a watermark embedding method. The method includes: inputting an original bitstream; determining a first frame for embedding a watermark in the input original bitstream; selecting one of frames after the first frame as a second frame; generating the first frame a bidirectional-coded frame (B frame) referring to the second frame; generating the second frame as a reference frame of the first frame; and embedding the watermark in the first frame generated as the B frame.