/**
 * Pure helper for composing a single thumbnail frame: pull a frame at
 * `atSec` and burn a headline on top with ffmpeg drawtext.
 *
 * Extracted from compose-thumbnail.ts so `compose_thumbnail_variants`
 * can call the same logic three times without duplicating the drawtext
 * filter construction.
 */
export interface ComposeThumbnailOpts {
    /** Source video path (already absolute or pre-resolved). */
    input: string;
    /** Output .jpg/.png absolute path. */
    output: string;
    /** Frame timestamp. */
    atSec: number;
    /** Headline text overlay (raw — escaping is handled internally). */
    text: string;
    /** Path to a TTF font; falls back to common system locations. */
    fontFile?: string;
    fontSize?: number;
    fontColor?: string;
    /** Empty string disables outline. Default 'black'. */
    outlineColor?: string;
    position?: "top" | "center" | "bottom";
    /** Optional output width (height auto). */
    width?: number;
    signal?: AbortSignal;
}
export interface ComposeThumbnailResult {
    ok: true;
    path: string;
    fontFile: string;
}
/**
 * Burn a headline onto a single frame from the source video and write
 * it to disk. Returns the resolved font path so callers can surface it
 * in their output.
 *
 * Throws on:
 *   - no system font found (and none provided)
 *   - ffmpeg drawtext exit ≠ 0
 */
export declare function composeThumbnailFrame(opts: ComposeThumbnailOpts, cwd?: string): Promise<ComposeThumbnailResult>;
export declare function pickFont(): string | undefined;
/**
 * Escape a string for ffmpeg drawtext's `text='...'` parameter.
 *
 * Rules (verified against real-world implementations):
 *   1. `\\` first  → `\\\\`
 *   2. `:`         → `\\:`
 *   3. `'`         → `\\'`
 *   4. `%`         → `\\%`  (because `%{...}` is used for runtime expansions)
 *   5. newlines    → literal `\\n` (drawtext renders as a line break)
 *
 * Backslash MUST come first so subsequent escapes don't double-escape.
 */
export declare function escapeDrawtextValue(text: string): string;
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