Reference: Metrics, Clock & Accessibility

These methods come from the metrics and abr mixin groups, two of the ten internal building blocks Composition Primitives lists as bundled into playerCoreMethods but not individually importable. Every NMVideoPlayer and NMMusicPlayer instance has them regardless, they’re just not a separate composeMixins() call away for a narrower build.

Metrics

metrics() reads a point-in-time snapshot; the same shape is also pushed periodically as the playback:metrics event on the interval set by setup({ metricsIntervalMs }). recordMetric() is the write side, backends call it to update their instrumented counters, and a plugin or consumer can use it for its own namespaced values.

Method	Signature	Notes
`metrics()`	`() => PlaybackMetrics`	Spreads the live counter map and appends a fresh `sessionDurationMs` computed from when the current item started. See Reference: Domain Types for every `PlaybackMetrics` field and which backends report it.
`recordMetric(name, value)`	`(name: string, value: number) => void`	Writes one named counter into the live store. `name` can be any string, an existing `PlaybackMetrics` key or a plugin’s own namespaced one, the extension slot (`[customMetric: string]: number \| null`) exists for exactly that.

Clock

now() is the distributed-clock timestamp source plugins use to coordinate across machines (Connect-style sync, telemetry timestamps) instead of calling Date.now() directly, so a consumer-supplied setup({ clockSource }) overrides every internal timestamp consistently.

Method	Signature	Notes
`now()`	`() => number`	Returns `options.clockSource()` when configured, `Date.now()` otherwise.

Accessibility

announce() is the player’s ARIA-live primitive. It inserts a visually-hidden element with role="status" and the requested aria-live level under the player container, then removes it shortly after so the DOM doesn’t accumulate stale nodes, screen readers pick up the text before the removal happens.

Method	Signature	Notes
`announce(text, level?)`	`(text: string, level?: AriaLiveLevel) => void`	`level` is `'polite'` (default) or `'assertive'`. No-ops server-side or before the container exists.

TypeScript

// A UI plugin announcing a quality switch without stealing focus
player.announce(`Quality switched to ${label}`);

// A blocking state that should interrupt a screen reader mid-sentence
player.announce('Playback error, retrying', 'assertive');

Bandwidth & capability checks

The same ABR primitives Quality Levels walks through for video apply unchanged to an adaptive-bitrate audio stream, they live here because both libraries compose the same abrMethods mixin.

Method	Signature	Notes
`bandwidth()`	`() => number`	Last-known throughput estimate in bits per second. A `bandwidthEstimator(fn)` override always wins over the active backend’s own live estimate (hls.js’s EWMA, for instance). Returns `0` when neither is available, never `NaN`, never a stale cache.
`bandwidthEstimator()` / `bandwidthEstimator(fn)`	`() => (() => number) \| undefined`, `(fn: () => number) => void`	Read the current override, or replace it, useful for sharing one measurement across multiple players on the same page.
`canPlay(profile)`	`(profile: { contentType: string; width?: number; height?: number; bitrate?: number; framerate?: number }) => Promise<CanPlayResult>`	Asks the platform’s `MediaCapabilities` bridge whether a content profile is decodable before offering it in a manual quality menu. Resolves `{ supported, smooth, powerEfficient }`.

Next steps

Reference: Utility Functions: the standalone, no-instance-required functions exported from the package root.
Reference: Testing Utilities: the /testing subpath used to write tests against plugins and the IPlayer contract.