jessikitty
112 lines
4.1 KiB
JavaScript
112 lines
4.1 KiB
JavaScript
import { spawn } from 'node:child_process';
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import { existsSync, statSync } from 'node:fs';
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import { basename, extname, join } from 'node:path';
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/*
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* ghost-media.js — server-side ghost sprite conversion.
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*
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* Turns an uploaded black-background ghost MP4 into a transparent animated
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* WebM (VP9 + alpha) plus an animated WebP fallback, using luma keying so the
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* black becomes transparent and the glow keeps soft semi-transparent edges.
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*
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* Shells out to the system `ffmpeg` binary (no npm dependency). If ffmpeg is
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* not installed, conversion fails gracefully and the caller keeps the original.
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*
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* This mirrors the standalone ghostify.sh pipeline so local and server output
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* match.
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*/
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const FFMPEG = process.env.FFMPEG_PATH || 'ffmpeg';
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// Tunables (env-overridable) — kept in sync with ghostify.sh defaults.
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const THRESH = process.env.GHOST_KEY_THRESHOLD || '0.06';
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const TOL = process.env.GHOST_KEY_TOLERANCE || '0.10';
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const SOFT = process.env.GHOST_KEY_SOFTNESS || '0.15';
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const FPS = process.env.GHOST_FPS || '15';
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const MAXW = process.env.GHOST_MAXW || '512';
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const WEBP_Q = process.env.GHOST_WEBP_QUALITY || '80';
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const VP9_CRF = process.env.GHOST_VP9_CRF || '30';
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// The shared luma-key + downscale filter chain.
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function keyChain() {
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const key = `format=rgba,lumakey=threshold=${THRESH}:tolerance=${TOL}:softness=${SOFT}`;
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const scale = `scale='min(iw,${MAXW})':-1:flags=lanczos`;
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return `${key},fps=${FPS},${scale}`;
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}
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function run(args) {
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return new Promise((resolve, reject) => {
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const proc = spawn(FFMPEG, args, { stdio: ['ignore', 'ignore', 'pipe'] });
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let stderr = '';
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proc.stderr.on('data', (d) => { stderr += d.toString(); });
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proc.on('error', reject); // e.g. ffmpeg not found (ENOENT)
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proc.on('close', (code) => {
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if (code === 0) resolve();
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else reject(new Error(`ffmpeg exited ${code}: ${stderr.slice(-500)}`));
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});
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});
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}
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/** True if a usable ffmpeg binary is on PATH. */
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export function ffmpegAvailable() {
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return new Promise((resolve) => {
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const proc = spawn(FFMPEG, ['-version'], { stdio: 'ignore' });
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proc.on('error', () => resolve(false));
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proc.on('close', (code) => resolve(code === 0));
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});
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}
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function outName(srcFilename, ext) {
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// wraith-1718.mp4 -> wraith-1718.webm / .webp, written alongside the source.
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const stem = basename(srcFilename, extname(srcFilename));
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return `${stem}.${ext}`;
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}
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/**
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* Convert a source MP4 (already saved in uploadDir) into transparent webm+webp.
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*
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* @param {string} uploadDir absolute uploads directory
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* @param {string} srcFilename the multer filename of the uploaded mp4
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* @returns {Promise<{ webm: string|null, webp: string|null }>} new filenames
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* (not full paths). Either may be null if that encode failed.
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*/
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export async function convertGhostMp4(uploadDir, srcFilename) {
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const srcPath = join(uploadDir, srcFilename);
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if (!existsSync(srcPath)) throw new Error(`source not found: ${srcPath}`);
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const vf = keyChain();
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const result = { webm: null, webp: null };
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// --- WebM (VP9 + alpha): the primary, browser-decoded sprite ---
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const webmName = outName(srcFilename, 'webm');
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try {
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await run([
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'-hide_banner', '-loglevel', 'error', '-y', '-i', srcPath,
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'-vf', vf, '-an',
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'-c:v', 'libvpx-vp9', '-pix_fmt', 'yuva420p',
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'-b:v', '0', '-crf', VP9_CRF, '-auto-alt-ref', '0',
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join(uploadDir, webmName),
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]);
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if (statSync(join(uploadDir, webmName)).size > 0) result.webm = webmName;
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} catch (e) {
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console.error('[ghost-media] webm encode failed:', e.message);
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}
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// --- WebP fallback: for iOS Safari / no-VP9-alpha browsers ---
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const webpName = outName(srcFilename, 'webp');
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try {
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await run([
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'-hide_banner', '-loglevel', 'error', '-y', '-i', srcPath,
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'-vf', vf, '-loop', '0', '-an',
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'-c:v', 'libwebp_anim', '-lossless', '0', '-q:v', WEBP_Q,
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'-preset', 'drawing', '-compression_level', '6',
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join(uploadDir, webpName),
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]);
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if (statSync(join(uploadDir, webpName)).size > 0) result.webp = webpName;
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} catch (e) {
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console.error('[ghost-media] webp encode failed:', e.message);
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}
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return result;
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}
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