/**
 * Display-name helpers for track menu rows. Sidecar tracks arrive with raw
 * wire values (`language: 'eng'`, `type: 'full'`); the menu shows the
 * localized language name with the variant as a suffix — `English (Full)` —
 * matching the v1 player. Localization depends on the player's UI language,
 * so this is composed at render time, never stored on the track.
 */
import type { SubtitleTrackRef } from '../../../types.js';
/**
 * Localized display name for a language code (ISO 639-1/2 or BCP-47),
 * rendered in `locale`. Returns `null` when the runtime cannot resolve the
 * code — callers decide their own fallback.
 */
export declare function languageDisplayName(code: string | undefined, locale: string): string | null;
/**
 * Menu row label for a subtitle track: `English (Full)`, `English (Sign)`,
 * `Nederlands (SDH)`. Falls back through variant-only → raw label →
 * language code → the provided default when fields are missing.
 */
export declare function subtitleTrackLabel(track: SubtitleTrackRef, locale: string, translate: (key: string) => string, fallback: string): string;