Live Stream: Buffer, Bitrate Ladder & Live-Edge Latency

Network Conditions

Average throughput 5.0 Mbps

Network volatility 40%

Bitrate Ladder (ABR)

Live Readouts

Buffer health

0.0 s

Current quality

—

Behind live edge

0.0 s

Stalls / stall time

0 / 0.0 s

How it works

A live stream is a race between three clocks: the encoder, which packages video into fixed-length segments in real time; the network, which delivers each segment's bytes at a fluctuating throughput; and the player, which drains one second of buffered video per real second of playback.

download time  = segment_size(bits) / throughput(bps)
buffer(t+dt)   = buffer(t) + segment_duration  [segment completes]
                          - dt                 [playback drains it]
latency_live   = encoded_time - played_time

If throughput ever drops below the requested bitrate for long enough, the buffer empties and playback stalls (rebuffers) until enough seconds are back in the buffer. Adaptive bitrate (ABR) tries to prevent this by watching buffer health rather than the network directly — a simple buffer-based ladder:

pick the highest rung i such that
   buffer_seconds >= threshold[i]
   thresholds ≈ {240p: 0s, 480p: 2×seg, 720p: 4×seg, 1080p: 6×seg}

Throughput / volatility — the simulated network's average capacity and how much it swings (real CDNs see congestion, Wi-Fi contention, cell handoffs).
Auto vs Manual — Auto runs the buffer-based ladder above every segment; Manual lets you force a rung and watch the buffer drain or fill in response.
Low-Latency mode — shortens the segment duration (this is exactly what LL-HLS / LL-DASH do), which shrinks the live-edge latency but leaves a thinner safety buffer, so stalls become more likely under the same network volatility.
Behind live edge — the real distinguishing feature of live streaming over on-demand: encoded content keeps arriving in real time, and every second spent buffering or downloading pushes the viewer further behind the true live moment.

240p 480p 720p 1080p

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