Video Packet Distribution Over Multiple Bearers for Error Control
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Solution Overview
Problem
Wireless networks experience bandwidth limitations and packet loss, leading to degraded video quality due to the predictive nature of modern video codecs, where errors propagate until refreshed by Intra frames, necessitating a mechanism for controlled packet loss to optimize decoded media quality.
Innovation Solution
A method and apparatus that distribute video packets over multiple bearers with unequal priority levels, favoring packet loss closer to the end of a Group of Pictures (GOP) to limit error propagation, by applying a bearer selection process based on the position of frames within the GOP, using Quality of Service (QoS) attributes to control which packets are discarded.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If video packets are transmitted over wireless networks using predictive encoding, then compression ratio is improved, but packet loss causes error propagation that degrades video quality
Solution Approach 1:
The video stream is segmented into Groups of Pictures (GOPs) with Intra frames at regular intervals. Each GOP contains multiple Predictive frames that depend on previous frames for decoding. By segmenting the video into these structured groups, the patent limits error propagation to within each GOP, preventing errors from affecting the entire video stream indefinitely.
Solution Approach 2:
Intra frames are injected into the video stream at predetermined intervals (every 1-2 seconds or at GOP boundaries) before errors can propagate throughout the entire stream. This preliminary refresh action resets spatial errors proactively, ensuring that even if packet loss occurs in Predictive frames, the impact is limited until the next Intra frame arrives.
2Reliability
If Intra frames are injected frequently to limit error propagation, then video quality is improved, but bandwidth consumption increases
Solution Approach 1:
Intra frames are injected periodically at regular intervals (every GOP or every 1-2 seconds) rather than continuously or randomly. This periodic refresh strategy balances the need to limit error propagation with bandwidth constraints, providing quality assurance only when necessary while allowing Predictive frames to use bandwidth more efficiently during intervals between Intra frames.
3Productivity
If packet loss occurs in early frames of a GOP, then bandwidth utilization is improved, but decoded video quality deteriorates significantly
Solution Approach 1:
The patent applies different protection strategies to different parts of the video stream based on their position within GOPs. Early frames in a GOP (especially Intra frames and early Predictive frames) are critical for subsequent decoding, so their loss has disproportionate impact. The system implicitly prioritizes protecting these critical local regions through the GOP structure, where loss in frame four affects 26 subsequent frames versus loss in later frames affecting fewer frames.
Data Source
AI summary
A method and apparatus distributes video packets over multiple bearers for providing unequal packet loss protection. The method includes receiving a plurality of packets that collectively includes video data from a group of pictures comprising a sequence of video frames, wherein the sequence includes one Intra frame at the beginning of the group of pictures followed by a plurality of Predictive frames. For each packet, the packet processing function: determines the corresponding frame that includes the video data; applies a bearer selection process to select one of multiple bearers for transporting the packet over an access network, wherein each bearer has a different quality of service level which influences the probability of the transported packets being dropped, wherein the bearer selection process is based on the position of the frame within the sequence of frames; and provides, to an access network entity, an indication of the selected bearer.