Computer & IT
Video Stream Concurrency Calculator
Calculate safe audience concurrency from edge, origin, and transcoder limits and compare the binding ceiling with forecast peak streams.
Wire rate per stream (Mbps)-
Raw edge bandwidth capacity (streams)-
Failover-safe edge capacity (streams)-
Origin-equivalent total audience capacity-
Failover-safe transcoder capacity-
Safe concurrent stream capacity-
Capacity margin versus forecast-
Forecast edge bandwidth (Gbps)-
Forecast origin bandwidth (Gbps)-
CDN offload share-
Decision view
CDN stream fan-out and three-ceiling concurrency gauge
CDN stream fan-out and three-ceiling concurrency gaugeViewer streams branch between CDN and origin while bandwidth and transcoder ceilings compete against forecast demand.
Exact scenario comparisonAverage delivered bitrate per stream (Mbps) changes while all other entered assumptions remain constant.
| Average delivered bitrate per stream (Mbps) | Wire rate per stream (Mbps) | Raw edge bandwidth capacity (streams) | Failover-safe edge capacity (streams) | Origin-equivalent total audience capacity | Failover-safe transcoder capacity | Safe concurrent stream capacity | Capacity margin versus forecast | Forecast edge bandwidth (Gbps) | Forecast origin bandwidth (Gbps) | CDN offload share |
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How to use Video Stream Concurrency Calculator
- Use a measured average across the active bitrate ladder.
- Enter origin share during peak cache conditions.
- Reserve capacity that must remain available during a failure.
Calculator guide
Understanding Video Stream Concurrency Calculator
Concurrent streaming capacity is limited by the first exhausted resource, not bandwidth alone. Edge egress, origin miss traffic, transcoder slots, bitrate, overhead, and failover reserve form separate ceilings.
Detailed calculation process
Detailed video-stream concurrency calculation
The default system has 25 Gbps edge, 4 Gbps origin, 5,200 transcoder slots, 12% origin share, and 20% failover reserve.
General formula: b_w=b*(1+o)C_e=floor(B_e*1000/b_w*(1-r))C_o=floor(B_o*1000/(b_w*p_o)*(1-r))C_t=floor(T*(1-r))C=min(C_e,C_o,C_t)M=C-D Each viewer consumes the wire bitrate at edge and only the origin-share fraction at origin. Failover reserve derates all three ceilings.
What each symbol means
Worked substitution with the default inputs
The default safe capacity is 4,115 concurrent streams, 85 below forecast.
Worked situations
Practical examples
- At 4.5 Mbps plus 8% overhead, each stream uses 4.86 Mbps.
- The default edge supports 4,115 failover-safe streams, lower than origin and transcoder ceilings.
Better inputs
Useful tips
- Run separate scenarios for premium 4K events.
- Use peak concurrent demand, not monthly viewers.
- Verify regional rather than global edge capacity.
Before relying on the result
Limitations and common mistakes
- The model uses one average bitrate and one origin share.
- It excludes per-title encoding, DRM, request rate, regional imbalance, and CDN contract limits.
- Origin-equivalent capacity assumes miss traffic scales proportionally with audience.
Reference
Key terms
- Wire rate
- Media bitrate plus entered delivery overhead.
- Origin share
- Audience traffic that must be served by origin rather than edge cache.
- Concurrency
- Streams active at the same time.
Important note
Confirm regional routing, CDN origin shield, encoder redundancy, DRM/license throughput, player startup bursts, and failure-mode tests before an event.
Frequently asked questions
Why is origin capacity expressed as total viewers?
Only the origin-share fraction of each viewer's traffic consumes origin egress.
Can a CDN offload transcoders?
Not in this model; transcoder slots remain a separate live-stream ceiling.
Why can capacity margin be negative?
Forecast peak demand exceeds the smallest safe ceiling.