Editing Signed Video Bitstreams via Macroblock Segmentation
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Solution Overview
Problem
Existing methods for editing signed video bitstreams require significant computational resources and delays due to the need for re-encoding and re-signing entire frames, even when only a portion of the video is edited, disrupting prediction-coding dependencies.
Innovation Solution
A method for editing signed video bitstreams that minimizes the need for re-signing by maintaining a one-to-one relationship between data units and macroblocks, allowing selective re-encoding of affected data units and preserving existing signatures through the use of an archive object containing fingerprints, thus confining the impact of edits to specific data units.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If re-encoding and re-signing entire frames is performed to edit signed video bitstreams, then data security and integrity are maintained, but computational resources are significantly consumed and processing delays occur
Solution Approach 1:
The video bitstream is segmented into individual macroblocks, each with its own data unit and signature unit. This allows editing operations to be applied selectively to only the macroblocks that are actually modified, rather than requiring re-processing of entire frames. The segmentation enables independent handling of edited and non-edited portions, maintaining security where needed while improving efficiency where not required.
Solution Approach 2:
The patent applies different processing quality to different parts of the video data. Edited macroblocks undergo full re-encoding and re-signing to maintain security, while non-edited macroblocks preserve their original signatures. This local differentiation ensures data security is maintained only where necessary (in edited regions) while avoiding unnecessary computational overhead in unaffected regions.
2Stability of the object's composition
If re-encoding and re-signing of neighboring frames is performed to maintain prediction-coding dependencies, then video integrity is preserved, but processing time and computational load increase significantly
Solution Approach 1:
The patent segments the video data into macroblock-level units with individual signatures, allowing prediction-coding dependencies to be maintained only for the specific macroblocks that are edited. This granular segmentation avoids the need to re-process entire frames or extend editing to all neighboring frames, thereby reducing processing delays while preserving necessary dependency relationships.
Solution Approach 2:
Instead of applying editing operations to all neighboring frames as a precaution, the patent applies partial action by re-encoding and re-signing only the specific macroblocks that are directly affected by the editing operation. This minimizes the scope of re-processing to the absolute minimum required, reducing computational load and processing time while still maintaining video integrity.
3Reliability
If entire frames are re-encoded and re-signed for editing operations, then data security is maintained, but the complexity of the editing process increases
Solution Approach 1:
The video bitstream is divided into discrete macroblock units, each with its own data unit and signature unit. This segmentation simplifies the editing process by allowing operations to be applied at the macroblock level rather than requiring complex frame-level processing. The modular structure makes it easier to identify, edit, and re-sign only the affected portions without involving the entire frame.
Solution Approach 2:
The patent applies partial action by performing re-encoding and re-signing operations only on the macroblocks that are actually edited, rather than processing entire frames. This reduces the complexity of the editing process by limiting the scope of operations to the minimum necessary areas, avoiding the computational overhead and procedural complexity of full-frame processing.
Data Source
Figure 1A~1B
Figure 2~3C
Figure 3D~4
AI summary
A signed video bitstream (B) obtained by prediction coding of a video sequence (V) includes data units (120) and associated signature units (130), wherein each data unit represents one macroblock (110) in a video frame (100). Each signature unit includes a digital signature (s(H1)) of a bitstring (H1) derived from fingerprints (h1, h2, ...), and each fingerprint has been computed from a macroblock reconstructed from one data unit associated with the signature unit. The bitstream is edited by: receiving a request to substitute a region; reconstructing a first set of macroblocks, in which said region is contained, and a second set of macroblocks referring to macroblocks in the first set; adding an archive object (140) that includes fingerprints of the first set of macroblocks; editing the first set of data units and encoding them; re-encoding the second set of macroblocks; and adding the new data units to the signed video bitstream.