Dynamic Bit Rate Adaptation for Streaming Over Fluctuating Bandwidth
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Solution Overview
Problem
Existing media transmission systems face challenges in adapting media file bandwidth to varying network conditions, leading to poor user experience due to video stalls and quality issues when streaming over mobile networks with fluctuating bandwidth.
Innovation Solution
A method and system that dynamically adjusts the encoding rate of media files by estimating the transmit time and display time of transcoded fragments, using a dynamic bit rate adapter to adjust the encoding rate based on these estimates, ensuring real-time transmission over varying bandwidth links.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the media file is encoded at a high encoding rate to maintain quality, then the media quality is improved, but the transmission fails when bandwidth is lower than required
Solution Approach 1:
The patent implements dynamic bit rate adaptation by continuously monitoring the transmit buffer status and adjusting the encoding rate in real-time. The encoder transitions from a static high encoding rate to a dynamic rate that adapts to current network conditions, preventing buffer overflow while maintaining optimal quality when bandwidth allows
Solution Approach 2:
The system establishes a feedback loop where the encoder monitors the transmit buffer status and uses this information to adjust the encoding rate. The encoder calculates the time to empty the transmit buffer and adjusts the bit rate accordingly, creating a closed-loop control system that balances quality and transmission reliability
2Reliability
If the encoding rate is reduced to match lower bandwidth, then transmission reliability is improved, but the media quality deteriorates
Solution Approach 1:
The encoding rate is dynamically adjusted based on real-time network conditions rather than being fixed at a low rate. The system monitors buffer status and adjusts the bit rate upward when bandwidth improves, thereby maintaining higher quality when possible while ensuring reliable transmission when bandwidth is constrained
Solution Approach 2:
The patent changes the encoding parameter (bit rate) dynamically based on network conditions. By monitoring the transmit buffer status and adjusting the encoding rate parameter in real-time, the system optimizes the balance between quality and reliability according to current bandwidth availability
3Device complexity
If static bandwidth adaptation is used, then device complexity is reduced, but the system cannot handle varying bandwidth conditions
Solution Approach 1:
The encoder performs self-adjustment by monitoring its own transmit buffer status and autonomously adjusting its encoding rate without requiring external control or complex adaptation systems. This self-service approach enables the system to handle varying bandwidth conditions with minimal additional complexity
Data Source
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AI summary
Audio and video streams of a media file are transcoded just-in-time by keeping the transcoding process synchronized to a wall clock. The transcoding is initially configured slightly faster than real-time. The transcoded frames are pushed from the transcoder through a variable bandwidth connection as soon as they are transcoded. Transcoding is then monitored periodically to assess the bandwidth that was available during the transmission of a transcoded buffer. Two time intervals are measured: a buffer interval which is the difference in the transcoded buffer timestamps of the previous two transmissions, and a clock interval corresponding to the real time transmission time of the last transcoded buffer. If a significant difference is observed, the transcoder bit rate is adjusted by a factor that is derived from that difference.