Function startExportJob

server.js:1061–1121

(job, args, expectedSeconds)

}

function startExportJob(job, args, expectedSeconds) {
  let cleanedUp = false;
  const cleanup = () => {
    if (cleanedUp) return;
    cleanedUp = true;
    for (const file of job.tempFiles || []) {
      fsp.unlink(file).catch(() => {});
    }
  };
  const child = spawn(FFMPEG, args, {
    cwd: ROOT,
    windowsHide: true,
    stdio: ["ignore", "ignore", "pipe", "pipe"]
  });

  child.stdio[2].on("data", chunk => {
    job.stderr += chunk.toString();
    if (job.stderr.length > 20000) job.stderr = job.stderr.slice(-20000);
  });

  let progressBuffer = "";
  child.stdio[3].on("data", chunk => {
    progressBuffer += chunk.toString();
    const lines = progressBuffer.split(/\r?\n/);
    progressBuffer = lines.pop() || "";
    for (const line of lines) {
      const [key, value] = line.split("=");
      if (key === "out_time_ms" || key === "out_time_us") {
        const seconds = Number(value) / 1000000;
        if (Number.isFinite(seconds)) {
          job.percent = Math.max(job.percent, Math.min(99, Math.round((seconds / expectedSeconds) * 100)));
          job.message = `Rendering... ${job.percent}%`;
        }
      }
      if (key === "progress" && value === "end") {
        job.percent = 100;
        job.message = "Finalizing...";
      }
    }
  });

  child.on("error", error => {
    job.status = "error";
    job.error = explainMissingTool(error, FFMPEG);
    job.message = "Export failed.";
    cleanup();
  });

  child.on("close", code => {
    if (code === 0) {
      job.status = "complete";
      job.percent = 100;
      job.message = "Export complete.";
    } else if (job.status !== "error") {
      job.status = "error";
      job.error = `ffmpeg exited with code ${code}`;
      job.message = "Export failed.";
    }