/**
 * ffmpeg x11grab recorder with NVIDIA NVENC hardware encoder.
 *
 * Captures the Xvfb virtual display directly with `ffmpeg -f x11grab` at a
 * fixed framerate, encoded straight to MP4 via `h264_nvenc` running on the
 * Cloud Run NVIDIA L4 GPU. Decouples clip recording from Chromium's
 * compositor speed AND from the CPU JPEG encoder that capped the previous
 * CDP `Page.captureScreenshot` path at ~9 fps.
 *
 * Why this works on Cloud Run when v1.3.10 (libx264) didn't:
 *   - v1.3.10 used CPU encoder (libx264) which competed with Chromium for
 *     vCPU on the same machine, giving 1.83 fps.
 *   - h264_nvenc offloads the entire encode to dedicated NVIDIA NVENC silicon
 *     on the L4 (separate from CUDA cores). Encode is essentially free CPU-side.
 *   - The L4 has 2× NVENC blocks and can sustain multiple 4K streams in
 *     parallel, so 1440x900@30fps is trivial.
 *
 * Lifecycle: one recorder instance per BEGIN_CLIP/END_CLIP. Xvfb itself
 * runs for the whole browser process lifetime.
 *
 * Refs:
 *   - https://docs.cloud.google.com/run/docs/tutorials/video-encoding
 *   - https://docs.nvidia.com/video-technologies/video-codec-sdk/13.0/ffmpeg-with-nvidia-gpu/index.html
 */
export interface FfmpegX11RecorderOptions {
    /** DISPLAY string (e.g. `:99`). */
    display: string;
    /** Capture region width in pixels. Should match Xvfb screen width. */
    width: number;
    /** Capture region height in pixels. Should match Xvfb screen height. */
    height: number;
    /** Target framerate. */
    fps: number;
    /** Absolute path to the output .mp4 file. */
    outputPath: string;
}
export interface FfmpegX11RecorderResult {
    outputPath: string;
    trimStartMs: number;
    durationMs: number;
}
export declare class FfmpegX11Recorder {
    private readonly opts;
    private process;
    private startedAt;
    private firstFrameAt;
    private lastReportedFrameLine;
    private stderrTail;
    constructor(opts: FfmpegX11RecorderOptions);
    start(): Promise<void>;
    stop(): Promise<FfmpegX11RecorderResult>;
}