Encrypted Video Bit Stream Temporal Synchronization
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Solution Overview
Problem
Existing video quality assessment systems face challenges in accurately synchronizing encrypted video bit streams with processed video sequences due to delays and packet losses during transmission, leading to inaccurate perceived video quality assessments.
Innovation Solution
A method and apparatus for temporally synchronizing encrypted video bit streams with processed video sequences by analyzing packet header information, extracting frame sizes and types, and matching features from the bit stream with those from the processed video sequence to align the bit stream with the displayed pictures, considering packet losses and errors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the video bit stream is transmitted over a network, then the video can be delivered to the user, but delays and packet losses occur causing temporal asynchrony between the bit stream and the processed video sequence
Solution Approach 1:
The patent performs preliminary extraction of timing information from packet headers during the transmission phase, storing this synchronization data in advance. This allows the receiver to have the timing information ready before the processed video sequence arrives, enabling accurate temporal alignment without waiting for the video data to arrive first.
Solution Approach 2:
The patent introduces an intermediary synchronization mechanism that uses packet header timing information as a mediator between the transmitted bit stream and the processed video sequence. This intermediary data structure carries the temporal relationship information needed to align the two streams that would otherwise be out of sync due to network transmission variations.
2Reliability
If the transmitted video bit stream is encrypted, then copyright protection is provided, but the quality assessment models cannot access the packet payload and related features from the elementary stream
Solution Approach 1:
The patent extracts only the necessary timing and synchronization information from the packet headers, which remain accessible even when the packet payload is encrypted. By taking out only the essential synchronization data that doesn't require decryption, the system maintains copyright protection while still obtaining the timing information needed for quality assessment.
Solution Approach 2:
The patent creates a copy of the timing information from the packet headers without needing to access or decrypt the encrypted payload. This copying approach allows the quality assessment system to work with synchronized timing data while the original encrypted stream remains protected and intact.
3Stability of the object's composition
If a de-jitter buffer is used to ensure smooth playback, then packet arrival time variations are compensated, but the temporal alignment between the bit stream and the processed video sequence becomes more complex
Solution Approach 1:
The patent performs preliminary extraction and storage of timing information from packet headers before the video data undergoes de-jitter buffering. By capturing the original transmission timing data in advance, the system can later align the buffered video output with the original bit stream timing without needing to track the complex internal state of the de-jitter buffer.
Data Source
Figure 1~2
AI summary
The invention relates to a method and apparatus for evaluating the quality of a video sequence by temporally synchronizing the encrypted input bit stream of a video decoder with the processed video sequence obtained by an external video decoder, the method comprising the steps of: a) supplying the encrypted input bit stream to an analysis module; b) analysing, in the analysis module, the packet header information of the encrypted input bit stream, and calculating the size and the type of the pictures contained in the bit stream; c) extracting, on the basis on the calculated picture sizes and types, features that are representative of the content depicted in the video pictures; d) extracting the type of content and respective features representative of the content from the pictures of the processed video sequence; e) comparing the features extracted in step d) from the current picture of the processed video sequence with the features extracted in step c) from the analysed pictures to compute the part of the bit stream that corresponds to the current PVS; f) wherein the part of the bit stream which corresponds to the current PVS is further input to a video quality assessment module; and g) estimating, by the video quality assessment module, a subjective quality score based on the obtained information from the bit stream and the processed video sequence.