What is Rebuffering?
Rebuffering occurs when media playback pauses because the player consumes buffered data faster than replacement data arrives. Playback resumes only after the buffer regains enough content.
How Rebuffering works
A streaming player maintains a time-based reservoir of downloaded, and possibly decoded, media ahead of the playhead. When segment arrival and processing fail to replenish that reservoir before it reaches zero, the player suspends advancement and rebuilds enough headroom to continue. Rebuffering is therefore an outcome across adaptation, CDN delivery, decoding, and device capacity, and its event timing should be captured alongside the rendition and buffer level that preceded it.
Key facts
- 1Startup buffering occurs before playback begins, whereas rebuffering interrupts an active session. Combining them into one delay metric hides two different user-visible failure modes.
- 2High nominal bandwidth does not prevent stalls when throughput varies below the selected rendition, segment requests have long tails, or decoding cannot keep pace with presentation.
- 3Aggressive bitrate reduction can shorten a stall but may create quality oscillation. Adaptation logic needs hysteresis and recent throughput or buffer evidence to avoid repeated switches.
When Rebuffering matters
Track rebuffering frequency and duration when tuning adaptive bitrate selection, segment delivery, and initial buffer size. Choosing a rendition above sustained throughput can cause repeated stalls despite high visual quality.