Encrypted Video Bit Rate Estimation via TCP ACK Analysis
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Solution Overview
Problem
Existing methods struggle to estimate media bit-rates of encrypted Adaptive Bit-Rate (ABR) video streams without decoding or accessing the video content, making it difficult to measure performance metrics like playback stalls and start delays in encrypted communication channels.
Innovation Solution
A system and method that monitor encrypted video streams in traffic bursts to estimate bit rates by analyzing communication patterns, using TCP acknowledgement numbers and identifying GET messages to calculate data volumes and bit rates, allowing for performance metric estimation without decrypting the stream.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If encrypted video streams are monitored to estimate bit rates, then performance metrics can be measured without decrypting content, but the inability to access video content directly limits measurement accuracy
Solution Approach 1:
The patent uses TCP acknowledgement numbers as an intermediary to estimate video stream bit rates. Instead of directly accessing encrypted video content, the system monitors TCP ACK packets that accompany the video stream transmission. By analyzing the sequence and timing of TCP acknowledgement numbers, the system can infer the actual video data transfer rate without needing to decrypt or access the encrypted video payload.
2Ease of operation
If TCP acknowledgement numbers are used to estimate data volumes, then bit rate calculation becomes possible without content access, but the indirect measurement method introduces estimation errors
Solution Approach 1:
The patent extracts only the necessary information (TCP acknowledgement numbers) from the communication packets to estimate video stream characteristics. By focusing solely on the TCP ACK field values and their temporal sequence, the system avoids the complexity of decrypting or analyzing video content while obtaining sufficient data to calculate bit rates and detect performance issues.
Solution Approach 2:
The patent replaces direct video content analysis with a computational model that substitutes physical video data examination with mathematical estimation based on TCP protocol behavior. The system uses algorithms that model the relationship between TCP acknowledgement patterns and actual video data transfer, substituting direct measurement with indirect computational inference.
3Reliability
If encrypted communication channels are used to protect video content, then security is improved, but performance monitoring and Quality-of-Service policies cannot be effectively implemented
Solution Approach 1:
The patent employs TCP acknowledgement numbers as a mediator that bridges the gap between encrypted video transmission and performance monitoring. These acknowledgement numbers are part of the unencrypted TCP protocol header that must remain visible for protocol operation, allowing network monitoring systems to extract performance metrics while the video payload remains securely encrypted.
Data Source
AI summary
Described embodiments include a system that includes a network interface and a processor. The processor is configured to monitor, via the network interface, a streaming of an encrypted video stream, in a sequence of traffic bursts, from a video server to a user terminal, and, based on the monitoring, and without decrypting the video stream, to estimate a bit rate at which the video stream was streamed, and to estimate, using the estimated bit rate, a performance metric of the video stream. Other embodiments are also described.