Adaptive Bitrate Adjustment via Bitrate Change Prediction

The system performs preliminary actions by pre-fetching video segments into the buffer before they are needed for playback. The buffer is proactively filled with future video data while network conditions are favorable, so that when network conditions deteriorate, playback can continue without interruption. This preliminary buffering action resolves the contradiction by preparing advance supplies of video data, reducing the need for real-time buffering during playback and thus minimizing delay.

The buffer acts as a cushion prepared in advance to absorb future network variances. By maintaining a buffer of pre-fetched video segments, the system creates a protective cushion that prevents playback interruptions when network conditions worsen. This beforehand cushioning allows the system to maintain reliable playback without requiring continuous real-time buffering, thereby reducing distribution delay while ensuring playback reliability.

Instead of continuously monitoring and adjusting bitrate based on buffer fill level, the system implements periodic ABR adjustments at predefined segment boundaries. The client device evaluates network conditions and buffer status at regular intervals (e.g., every few segments) and makes discrete bitrate changes only at segment transitions. This periodic action reduces the frequency of adjustments, preventing playback disruptions while maintaining adequate video quality adaptation to changing network conditions.

The system maintains continuous video playback by ensuring that ABR adjustments occur only at segment boundaries, not during active playback of a segment. This continuity principle ensures that once a segment is downloaded and decoded, it plays without interruption regardless of subsequent bitrate changes. The useful action of video playback continues uninterrupted, while quality adaptation happens between segments, resolving the contradiction between adaptability and playback continuity.

The system extracts the ABR adjustment logic from the TCP congestion control layer and implements it at the application layer. Instead of relying on TCP's packet-level retransmission adjustments, the client device directly monitors received bitrate and proactively requests segments at appropriate quality levels. This extraction of ABR control from TCP congestion management eliminates the iterative retransmission process, reducing delay while maintaining network fairness through direct bitrate adaptation based on observed network conditions.

The client device performs preliminary assessment of network conditions by monitoring received bitrate over a window of segments, then proactively selects the appropriate ABR level for future segment requests. This preliminary action allows the system to anticipate suitable bitrate levels before buffer underrun occurs, avoiding the reactive retransmission delays inherent in TCP congestion control. By predicting appropriate bitrate levels in advance, the system achieves bandwidth adaptation without the time penalty of TCP's iterative congestion avoidance mechanisms.