/**
 * Type-guard that checks whether a numeric codec value represents H265/HEVC.
 *
 * @param codec - The codec identifier to test.
 * @returns `true` when `codec` equals {@link KnownCodec.H265} (173).
 */
export declare function isH265Codec(codec: number): boolean;
/**
 * Check whether a codec requires MSE delivery because it cannot be transported via SRTP.
 *
 * Currently only H265 may require MSE: the mediaserver's `webrtcSrtpTransportEnableH265`
 * flag is off by default, and even when on, not all browsers decode H265 via WebRTC.
 * This function conservatively returns true for H265 when the browser lacks SRTP H265
 * support — callers should try SRTP first and use the reactive transcoding fallback
 * as a safety net.
 */
export declare function codecRequiresMse(codec: number): boolean;
/**
 * Check whether the browser supports the MediaSource Extensions API.
 * Required for MSE delivery mode.
 */
export declare function isMseSupported(): boolean;
/**
 * Check whether the browser can decode H265/HEVC via WebRTC SRTP transport.
 *
 * Uses `RTCRtpReceiver.getCapabilities('video')` to check for H265 codec support.
 * Returns false if the API is unavailable or H265 is not listed.
 *
 * Result is memoized — codec capabilities do not change within a session.
 */
export declare function browserSupportsH265WebRTC(): boolean;
/**
 * Reset the memoized H265 WebRTC support cache.
 * Exposed for testing only — browser capabilities don't change at runtime.
 * @internal
 */
export declare function _resetH265Cache(): void;
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