Error Resilient Video Transmission via Adaptive Retransmission
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Solution Overview
Problem
Existing real-time digital video transmission systems face challenges in delivering error-free audio/video content to wireless devices due to packet loss caused by physical obstructions and environmental factors, which are not adequately addressed by current technologies.
Innovation Solution
A block-based hybrid video codec (MPEG-X, H.26X) is used to compress video frames into fixed or variable size packets, with synchronized error concealment and retransmission schemes implemented at both the encoder and decoder based on instantaneous feedback, allowing for adaptive bit budget allocation between source encoding and packet retransmission.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If packet retransmission is implemented to handle lost video packets, then video transmission reliability is improved, but transmission delay increases
Solution Approach 1:
The patent implements preliminary error concealment at the encoder side before transmission, preparing alternative video data in advance. When packets are lost during transmission, the decoder can immediately use the pre-prepared concealed data without waiting for retransmission, thus reducing the effective delay while maintaining reliability
Solution Approach 2:
The system dynamically adapts its error handling strategy based on channel conditions. When packet loss is detected, the system switches between using retransmitted packets and using error-concealed packets, optimizing the balance between reliability and delay in real-time based on the specific transmission scenario
2Reliability
If error concealment is performed at both encoder and decoder, then video quality under packet loss is improved, but system complexity increases
Solution Approach 1:
The patent merges the error concealment functionality into the existing encoder and decoder structures. The encoder's motion estimation and compensation modules are reused for error concealment by substituting lost reference frames with concealed frames, and the decoder integrates similar concealment logic. This merging approach improves video quality under packet loss while avoiding the need for entirely separate error concealment systems, thus limiting the increase in complexity
3Productivity
If bit budget is allocated for both source encoding and packet retransmission, then overall transmission effectiveness is improved, but the complexity of bit rate control increases
Solution Approach 1:
The patent implements feedback-based bit rate control where the encoder receives information about packet loss from the decoder and adjusts its encoding strategy accordingly. The feedback mechanism allows the system to dynamically allocate bit budget between source encoding and retransmission based on actual channel conditions, improving overall transmission effectiveness while using a relatively simple feedback loop rather than complex predictive models
Data Source
AI summary
Systems and methods for delivering real-time video imagery to a receiver over a channel. A current video frame is captured and digitized. The digitized frame is divided into a plurality of macroblocks. For each macroblock an intra, inter or skip mode coding mode is determined. Based on instantaneous feedback received from a receiver regarding successfully received video packets for a prior video frame, a quantization parameter is set and the macroblocks are encoded in accordance with their respective selected coding mode. Synchronized error concealment is performed at both the encoder and decoder sides of the system and retransmission of lost video packets, using an adaptive retransmission scheme, are performed in accordance with the instantaneous feedback from the receiver.