Function toneFilter

server.js:138–149

(tone, frames, fps, scope = "join")

}

function toneFilter(tone, frames, fps, scope = "join") {
  if (!tone || frames <= 0) return "";
  const brightness = Math.max(-0.18, Math.min(0.18, Number(tone.brightnessDelta) || 0));
  const contrast = Math.max(0.8, Math.min(1.25, Number(tone.contrastRatio) || 1));
  if (Math.abs(brightness) < 0.003 && Math.abs(contrast - 1) < 0.01) return "";
  if (scope === "full") {
    return `eq=brightness=${brightness.toFixed(6)}:contrast=${contrast.toFixed(6)},`;
  }
  const duration = Math.max(1 / fps, frames / fps);
  const fade = `max(0\\,1-t/${duration.toFixed(6)})`;
  return `eq=brightness='${brightness.toFixed(6)}*${fade}':contrast='1+${(contrast - 1).toFixed(6)}*${fade}':eval=frame,`;
}

function fitFilter() {
  return "scale=1280:720:force_original_aspect_ratio=decrease,pad=1280:720:(ow-iw)/2:(oh-ih)/2,setsar=1";