fp/services/our/scripts/analyze.ts

import { spawn } from "child_process";

export interface AudioStats {
  peak: number;           // True peak in dBTP
  lufsIntegrated: number; // LUFS-I
  lra: number;            // Loudness range
}

async function runFFmpeg(args: string[]): Promise<string> {
  return new Promise((resolve, reject) => {
    console.log("Running ffmpeg:", args.join(" "));
    const ff = spawn("ffmpeg", args);

    let stdout = "";
    let stderr = "";

    ff.stdout.on("data", (data) => {
      const str = data.toString();
      stdout += str;
      process.stdout.write(str); // debug passthrough
    });

    ff.stderr.on("data", (data) => {
      const str = data.toString();
      stderr += str;
      process.stdout.write(str); // debug passthrough
    });

    ff.on("close", (code) => {
      console.log("ffmpeg exited with code:", code);
      if (code === 0) resolve(stdout + "\n" + stderr);
      else reject(new Error(stderr));
    });
  });
}

function parseEbur128(output: string): AudioStats {
  const lines = output.split("\n").map(l => l.trim());

  let lufsIntegrated = NaN;
  let lra = NaN;
  let peak = NaN;

  let inTruePeak = false;

  for (const line of lines) {
    // Integrated loudness (LUFS-I)
    const iMatch = line.match(/^I:\s*(-?\d+(\.\d+)?) LUFS/);
    if (iMatch) lufsIntegrated = parseFloat(iMatch[1]);

    // Loudness range (LRA)
    const lraMatch = line.match(/^LRA:\s*(-?\d+(\.\d+)?)/);
    if (lraMatch) lra = parseFloat(lraMatch[1]);

    // True peak (dBTP)
    if (line === "True peak:") inTruePeak = true;
    if (inTruePeak) {
      const pMatch = line.match(/Peak:\s*(-?\d+(\.\d+)?) dBFS/);
      if (pMatch) {
        peak = parseFloat(pMatch[1]);
        inTruePeak = false;
      }
    }
  }

  return { lufsIntegrated, lra, peak };
}

export async function analyzeAudio(inputFile: string): Promise<AudioStats> {
  const args = [
    "-hide_banner",
    "-i", inputFile,
    "-filter_complex", "ebur128=peak=true:metadata=1:framelog=verbose",
    "-f", "null",
    "-",
  ];

  const output = await runFFmpeg(args);
  return parseEbur128(output);
}

// Test
(async () => {
  const stats = await analyzeAudio("/home/cj/Videos/28years/voiceover-compressed2.wav");
  console.log("FINAL STATS:", stats);
})();