Packetized Video Decoding with Selective Retransmission Control
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Solution Overview
Problem
Existing data communication technologies face challenges in efficiently managing packet loss during real-time video transmissions, particularly in video conferencing, as they often result in delays and network congestion due to unnecessary retransmissions of packets that do not significantly degrade video quality.
Innovation Solution
A method and apparatus for selectively retransmitting lost packets based on an assessment of the cost of retransmission and the quality of decoding partial frames, using packet loss state information embedded in FEC packets to determine whether to retransmit missing packets, especially focusing on distinguishing between source and error correction packets.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If all lost packets are retransmitted to ensure complete video quality, then video quality is improved, but network congestion and delays increase
Solution Approach 1:
The patent applies local quality by differentiating between critical and non-critical packets, applying different retransmission strategies to different parts of the video data stream. Critical packets (e.g., P-frames, B-frames) are retransmitted to maintain quality, while non-critical packets (e.g., I-frames with minor losses) are allowed to degrade, optimizing the balance between quality and delay.
Solution Approach 2:
The system dynamically changes the retransmission parameter based on packet type and video frame importance. By adjusting which packets are retransmitted based on their criticality, the system adapts the reliability parameter locally, reducing overall retransmission delay while maintaining acceptable video quality.
2Reliability
If redundant FEC packets are transmitted to correct packet loss, then packet loss recovery is improved, but network bandwidth consumption increases
Solution Approach 1:
The patent applies partial action by transmitting FEC packets only for critical video frames rather than all frames. This selective approach provides sufficient error correction capability for important data while reducing the total quantity of FEC packets transmitted, thereby conserving network bandwidth.
Solution Approach 2:
The system makes FEC packets multi-functional by using them selectively for different frame types based on their importance. The same FEC mechanism serves both critical and non-critical frames, but with differentiated application levels, optimizing bandwidth usage while maintaining packet loss recovery capability.
3Reliability
If NACK requests are sent for all lost packets, then packet retransmission reliability is improved, but network congestion increases
Solution Approach 1:
The patent applies local quality by sending NACK requests selectively based on packet criticality. Instead of uniformly requesting retransmission for all lost packets, the system evaluates each lost packet's importance and generates NACK requests only for critical packets, reducing the number of retransmission requests and thereby reducing network congestion.
Solution Approach 2:
The system applies partial action by sending NACK requests for only a subset of lost packets—specifically those that are critical to video quality. This partial retransmission approach maintains acceptable reliability for important data while reducing the total number of NACK requests, thereby mitigating network congestion.
Data Source
AI summary
A method for decoding a packetized video signal including at least one encoded frame. In one case, the method includes receiving at least one FEC packet at a receiving station. The receiving station uses embedded data associated with the FEC packet to obtain more accurate knowledge of the packet loss state of the media packets. This improved knowledge can allow the receiver to make better use of packet retransmission requests. The embedded data associated with the FEC packet can include in some cases a base sequence number and a packet mask.