Signed Video Bitstream Editing with Macroblock-Level Signatures
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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 small portion is edited, disrupting prediction-coding dependencies.
Innovation Solution
A method that edits signed video bitstreams by substituting regions while preserving signatures of unaffected macroblocks, using data units that represent at most one macroblock, and re-encoding only those macroblocks directly or indirectly affected by the edit, with an optional archive object to validate the edited bitstream.
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 and processing time are significantly consumed
Solution Approach 1:
The video frame is segmented into multiple macroblocks, each with its own data unit and signature unit. This allows selective editing of individual macroblocks without requiring re-processing of the entire frame, thus maintaining security while improving computational efficiency.
Solution Approach 2:
Different parts of the video frame (macroblocks) are treated differently based on whether they are affected by editing. Only the edited macroblocks and those with prediction dependencies are re-encoded and re-signed, while unaffected macroblocks retain their original signatures, optimizing the balance between security and efficiency.
2Stability of the object's composition
If re-encoding and re-signing of entire frames is performed, then prediction-coding dependencies are maintained, but processing delays increase
Solution Approach 1:
The video sequence is divided into independent macroblocks with individual data units. This segmentation allows selective re-encoding of only those macroblocks affected by editing, preserving prediction dependencies while minimizing processing delay.
Solution Approach 2:
Instead of re-encoding entire frames, only the necessary portion (affected macroblocks and those with prediction references) is re-encoded. This partial action maintains prediction-coding integrity while significantly reducing processing time.
3Productivity
If selective editing of macroblocks is performed without re-encoding affected regions, then computational resources are saved, but prediction-coding dependencies are disrupted
Solution Approach 1:
The system identifies and processes only the local regions (macroblocks) that are affected by editing or have prediction dependencies on edited regions. This localized processing maintains prediction-coding stability while avoiding unnecessary computation on unaffected areas.
Solution Approach 2:
The system uses feedback from the editing operation to determine which macroblocks require re-encoding. By analyzing prediction dependencies and reference relationships, the system dynamically identifies the minimal set of macroblocks that must be re-processed to maintain coding integrity.
Data Source
AI summary
A signed video bitstream obtained by prediction coding of a video sequence includes data units and associated signature units, wherein each data unit represents at most one macroblock in a video frame of the video sequence, and each signature unit includes a digital signature of a bitstring derived from fingerprints of exactly one associated data unit each. The bitstream is edited by: receiving a request to substitute a region; determining 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 that includes fingerprints of a first and a second set of data units, which represent the first and second set of macroblocks; editing the first set of data units in accordance with the request to substitute; and re-encoding the second set of data units.