source: Klonkt/src/services/VideoCoverService.js@ b5a09ce2

/**
 * VideoCoverService — turn an animated cover into a small, Safari-friendly muted loop video.
 *
 * Safari renders animated WebP poorly; a muted <video> loop plays smoothly everywhere (iOS too).
 * ffmpeg-static can't DECODE an animated WebP, so we decode it with node-webpmux (pure JS/WASM,
 * NO native deps → installs on every platform, never breaks `npm ci`) into RGBA frames, then
 * encode with the bundled ffmpeg-static into an H.264 MP4 (yuv420p + faststart + no audio) plus a
 * JPG poster frame. A real uploaded video goes straight through ffmpeg. Both are best-effort: on
 * any failure we return null and the caller keeps the still image.
 */
import { execFile } from 'child_process';
import { promisify } from 'util';
import fs from 'fs';
import path from 'path';
import ffmpegPath from 'ffmpeg-static';
import WebP from 'node-webpmux';

const execFileP = promisify(execFile);
const MAX_SECONDS = 60; // cap a cover loop at one minute

let _lib = null;
function ensureLib() { if (!_lib) _lib = WebP.Image.initLib(); return _lib; }

// True if the file is an animated WebP (a VP8X chunk with the animation flag set).
export function isAnimatedWebp(filePath) {
  try {
    if (path.extname(filePath).toLowerCase() !== '.webp') return false;
    const fd = fs.openSync(filePath, 'r');
    try {
      const b = Buffer.alloc(40);
      const n = fs.readSync(fd, b, 0, 40, 0);
      return n >= 21 && b.toString('ascii', 12, 16) === 'VP8X' && (b[20] & 0x02) !== 0;
    } finally { fs.closeSync(fd); }
  } catch { return false; }
}

// Animated WebP → muted loop MP4 + JPG poster. Returns { videoPath, posterPath } or null.
export async function animatedWebpToVideo(srcPath, outDir, baseName) {
  let rawPath = null;
  try {
    if (!ffmpegPath) return null;
    await ensureLib();
    const img = new WebP.Image();
    await img.load(srcPath);
    if (!img.hasAnim || !img.anim || !Array.isArray(img.anim.frames) || img.anim.frames.length < 2) return null;
    const W = img.width, H = img.height, n = img.anim.frames.length;
    const fps = Math.max(1, Math.min(30, Math.round(1000 / (img.anim.frames[0].delay || 100))));
    // getFrameData(i) returns the FULL-canvas RGBA (W*H*4) for frame i (already composited).
    const bufs = [];
    for (let i = 0; i < n; i++) bufs.push(Buffer.from(await img.getFrameData(i)));
    await fs.promises.mkdir(outDir, { recursive: true });
    rawPath = path.join(outDir, baseName + '.rgba.tmp');
    await fs.promises.writeFile(rawPath, Buffer.concat(bufs));
    const videoPath = path.join(outDir, baseName + '.mp4');
    const posterPath = path.join(outDir, baseName + '.jpg');
    await execFileP(ffmpegPath, ['-hide_banner', '-loglevel', 'error',
      '-f', 'rawvideo', '-pix_fmt', 'rgba', '-s', `${W}x${H}`, '-r', String(fps), '-i', rawPath,
      '-vf', 'pad=ceil(iw/2)*2:ceil(ih/2)*2', // yuv420p needs even dimensions
      '-c:v', 'libx264', '-pix_fmt', 'yuv420p', '-movflags', '+faststart', '-an', '-y', videoPath],
      { timeout: 60000 });
    await execFileP(ffmpegPath, ['-hide_banner', '-loglevel', 'error',
      '-f', 'rawvideo', '-pix_fmt', 'rgba', '-s', `${W}x${H}`, '-i', rawPath,
      '-frames:v', '1', '-y', posterPath], { timeout: 30000 });
    return { videoPath, posterPath };
  } catch (e) {
    console.warn('[videocover] animated webp → mp4 failed:', e.message);
    return null;
  } finally {
    if (rawPath) try { await fs.promises.unlink(rawPath); } catch { /* ignore */ }
  }
}

// An uploaded video → muted loop MP4 (scaled ≤1280w, capped 60s) + JPG poster. ffmpeg decodes
// every video format, so no node-webpmux here. Returns { videoPath, posterPath } or null.
export async function videoToLoop(srcPath, outDir, baseName) {
  try {
    if (!ffmpegPath) return null;
    await fs.promises.mkdir(outDir, { recursive: true });
    const videoPath = path.join(outDir, baseName + '.mp4');
    const posterPath = path.join(outDir, baseName + '.jpg');
    await execFileP(ffmpegPath, ['-hide_banner', '-loglevel', 'error',
      '-i', srcPath, '-t', String(MAX_SECONDS),
      '-vf', "scale='min(1280,iw)':-2,pad=ceil(iw/2)*2:ceil(ih/2)*2",
      '-c:v', 'libx264', '-pix_fmt', 'yuv420p', '-movflags', '+faststart', '-an', '-y', videoPath],
      { timeout: 120000 });
    await execFileP(ffmpegPath, ['-hide_banner', '-loglevel', 'error',
      '-i', videoPath, '-frames:v', '1', '-y', posterPath], { timeout: 30000 });
    return { videoPath, posterPath };
  } catch (e) {
    console.warn('[videocover] video → loop failed:', e.message);
    return null;
  }
}

export default { isAnimatedWebp, animatedWebpToVideo, videoToLoop };