Telemetry (Prometheus)

Scout exposes a Prometheus-compatible metrics endpoint that publishes per-stream CMSD-MQA quality scores. The endpoint is enabled by default for Standard and higher licenses.

Configuration

prometheusEnabled: true   # set to false to disable
prometheusPort: 9090
prometheusPath: /metrics

Accessing the metrics

Metrics are served at:

http://<your-server>:9090/metrics

The response uses the Prometheus text exposition format (text/plain; version=0.0.4).

Metrics reference

Metric	Description
`scout_stream_psnr_db{stream="<id>"}`	PSNR of the most recently completed segment for this stream (dB). Omitted if MQA is not enabled for the stream or no segment has completed yet.
`scout_stream_ssim{stream="<id>"}`	SSIM of the most recently completed segment (0–1).
`scout_stream_vmaf{stream="<id>"}`	VMAF score of the most recently completed segment (0–100). Omitted unless `cmsdVmafEnabled=true` for the stream and libvmaf is available.
`scout_stream_bitrate_kbps{stream="<id>"}`	Current encoded bitrate for the stream (kbps), from the stream metadata cache.
`scout_headers_injected_total{stream="<id>"}`	Running count of `CMSD-Static` headers injected for this stream since plugin start.
`scout_alerts_fired_total{stream="<id>"}`	Running count of quality alerts fired for this stream since plugin start (Enterprise tier only; always zero on Standard and Integration).

Score sources

The Prometheus endpoint merges scores from two sources for each stream:

Computed scores — PSNR / SSIM / VMAF computed on-device from the AMS encoder pipeline (requires cmsdMqaEnabled=true per stream, configured via the MQA REST API).
Injected scores — pushed by an external tool via the MQA REST ingest endpoint (requires restApiEnabled: true; see Media Quality Assessment (MQA)).

Injected scores take precedence over computed scores for the same stream and metric.