Adaptive Bitrate Encoding for Video Latency Control
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Solution Overview
Problem
Interactive video applications over unmanaged networks face significant playback latency due to fluctuations in network bandwidth and latency, leading to undesirable delays and a poor user experience, as existing technologies lack effective methods to adjust encoding rates in response to network conditions.
Innovation Solution
The method involves calculating a delay cost function based on network latency and available bandwidth to adjust the encoding bitrate of audiovisual data, ensuring optimal playback latency by varying the amount of new frame data transmitted and modifying source data generation accordingly, using a delay cost function that captures user tolerance for different applications.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If buffering is used to address throughput fluctuations, then reliability of video delivery is improved, but playback latency increases
Solution Approach 1:
The patent applies dynamics by making the buffer size dynamic rather than fixed. The server continuously adjusts the buffer size based on real-time network conditions, specifically adapting to throughput fluctuations. This allows the system to maintain reliability during network variations while minimizing latency when network conditions are good, resolving the contradiction between reliability and latency.
Solution Approach 2:
The patent implements feedback mechanisms where the server monitors network throughput and buffer status in real-time, then adjusts encoding parameters and buffer sizes accordingly. This closed-loop control allows the system to respond to network conditions, maintaining reliable delivery without excessive latency by continuously optimizing buffer management based on actual network performance.
2Device complexity
If fixed encoding bitrate is used, then device complexity is reduced, but adaptability to network conditions deteriorates
Solution Approach 1:
The patent applies parameter changes by dynamically adjusting encoding parameters (such as bitrate, resolution, or compression level) based on network conditions. The server modifies these parameters in response to detected network throughput, allowing the system to adapt to varying network conditions while maintaining acceptable complexity through automated parameter adjustment rather than complex manual configuration.
Solution Approach 2:
The system transitions from static fixed bitrate encoding to dynamic adaptive encoding. The encoding parameters are continuously adjusted based on real-time network feedback, enabling the system to adapt to changing network conditions without requiring complex manual intervention, thus balancing adaptability with manageable system complexity.
3Reliability
If larger buffer size is used, then video delivery reliability is improved, but playback latency increases
Solution Approach 1:
The patent implements dynamic buffer size adjustment rather than using a fixed large buffer. The buffer size is continuously adapted based on network throughput conditions and playback latency measurements. This allows the system to maintain reliable video delivery during network fluctuations while minimizing buffer size (and thus latency) when network conditions are stable, resolving the contradiction between reliability and latency.
Solution Approach 2:
The system uses preliminary actions by pre-buffering video data before playback, but the amount of pre-buffering is dynamically determined. The server prepares video segments in advance and adjusts the buffering strategy based on predicted and actual network conditions, ensuring reliable delivery while minimizing unnecessary latency from excessive pre-buffering.
Data Source
AI summary
Systems and methods are provided for reducing and controlling playback latency in an unmanaged, buffered data network. A delay cost function is determined, the function representing the effect of playback latency on end user experience. An encoder transmits audiovisual data through the network to a client device. Network latency is measured, and the delay cost function is evaluated to establish an encoding bitrate for the encoder. The encoding of the audiovisual data is altered in response to dynamic network conditions, thereby controlling end-to-end playback latency of the system, which is represented by the playout length of data buffered between the encoder and the client device.