/**
 * Silence detection and DC-offset removal.
 */
export interface SilenceOptions {
    /**
     * Level below which audio counts as silent, in dBFS. Defaults to -60.
     *
     * A literal zero threshold almost never works: real recordings carry a noise
     * floor from the preamp and converter, so "silence" is quiet, not absent.
     */
    threshold?: number;
    /**
     * Window in milliseconds over which level is measured. Defaults to 10.
     *
     * Measuring per sample would treat every zero crossing of a loud waveform as
     * silence, cutting holes through the middle of a note.
     */
    windowMs?: number;
}
/** A detected span of silence, in frames. */
export interface SilentRange {
    start: number;
    end: number;
}
/** Finds every silent span. */
export declare function detectSilence(channels: readonly Float32Array[], sampleRate: number, options?: SilenceOptions): SilentRange[];
export interface TrimSilenceOptions extends SilenceOptions {
    /** Trim leading silence. Defaults to `true`. */
    start?: boolean;
    /** Trim trailing silence. Defaults to `true`. */
    end?: boolean;
    /**
     * Silence to leave in place, in milliseconds. Defaults to 0.
     *
     * Trimming hard to the first audible sample clips the attack of the first
     * note and sounds abrupt; a few milliseconds of lead-in usually sounds right.
     */
    paddingMs?: number;
}
/** Removes silence from the start and/or end. */
export declare function trimSilence(channels: readonly Float32Array[], sampleRate: number, options?: TrimSilenceOptions): Float32Array[];
/**
 * Removes DC offset by subtracting each channel's mean.
 *
 * A DC offset eats headroom asymmetrically and can produce a click at the start
 * and end of playback. It usually comes from a poorly-biased ADC or an analogue
 * input stage, and shows up as a waveform that is not centred on zero.
 */
export declare function removeDcOffset(channels: readonly Float32Array[]): Float32Array[];