Miracast Source Device Frame Skipping and Encoder Reconfiguration
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Solution Overview
Problem
Miracast systems face significant user experience degradation due to packet loss and corruption in wireless video transmission, particularly with H.264-encoded video data, leading to freezing or artifacts in video playback, exacerbated by high bit error rates and unreliable WiFi links.
Innovation Solution
The implementation of a method in the source device to dynamically adjust video streaming by skipping frames, reconfiguring the video encoder, or changing the video format based on link quality information, and incorporating recovery information in packets to facilitate seamless decoding at the sink device, even in the presence of packet loss.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If H.264 video compression is used to achieve high compression ratio, then video data transmission efficiency is improved, but sensitivity to packet loss increases causing freezing and artifacts
Solution Approach 1:
The patent applies preliminary action by proactively detecting packet loss conditions and switching to resilient encoding mode before severe degradation occurs. The system monitors packet loss rates and preemptively adjusts encoding parameters (such as increasing I-frame frequency or using more robust prediction modes) to prevent freezing and artifacts, rather than waiting for quality degradation to manifest.
Solution Approach 2:
The patent implements parameter changes by dynamically adjusting video encoding parameters based on network conditions. When packet loss is detected, the system modifies parameters such as frame type selection, quantization levels, and reference frame usage to create more resilient video streams that can withstand transmission errors, thus maintaining playback reliability while preserving compression efficiency.
2Loss of energy
If variable length coding is used for compression, then compression ratio is improved, but decoding reliability deteriorates due to undetected data corruption
Solution Approach 1:
The patent applies feedback by implementing error detection mechanisms that monitor the decoding process for signs of corruption. When data corruption is detected in variable length coded streams, the system triggers error concealment routines or requests retransmission, creating a feedback loop that maintains decoding reliability without sacrificing the compression benefits of variable length coding.
Solution Approach 2:
The patent uses cheap short-living objects by implementing disposable error protection codes or checksums that are calculated and verified for each video frame or packet. These lightweight verification mechanisms are discarded after use but provide sufficient protection against undetected corruption in variable length coded data, maintaining reliability without significant overhead.
3Reliability
If I-frames are transmitted frequently to improve recovery from packet loss, then video quality is improved, but bandwidth consumption increases
Solution Approach 1:
The patent implements dynamics by making the I-frame transmission frequency adaptive rather than static. The system dynamically adjusts the frequency of I-frame transmission based on real-time network conditions, packet loss rates, and buffer status. When network conditions deteriorate, I-frame frequency increases to improve recovery capability; when conditions improve, the frequency decreases to conserve bandwidth, optimizing the trade-off between reliability and bandwidth consumption.
Data Source
AI summary
A method is implementable in a source device operable to provide, via a wireless channel, a video stream to a sink device for display by the sink device. The method includes receiving link quality information indicative of a condition of the wireless channel and/or performance of communications between the source device and the sink device via the wireless channel. The method also includes determining a measure of network congestion based on the link quality information, and, based on the measure of network congestion, skipping one or more, but not all, video frames of a plurality of video frames in the video stream, such that the one or more video frames are not provided to the sink device, reconfiguring a video encoder operating on the plurality of video frames, such that an output bit rate of the video encoder is changed, and/or changing a video format of the video stream.