fp/services/our/src/tasks/analyzeAudio.ts

/**
 * Analyze the video's audio track using ITU-R BS.1770/EBU R128
 * to extract Integrated Loudness (LUFS-I), Loudness Range (LRA),
 * and True Peak (dBTP). This helps identify which VODs/streamers
 * maintain consistent, listener-friendly audio setups.
 *
 * ## LUFS Reference
 * Apple Music -16 LUFS
 * YouTube     -13 LUFS
 * Spotify     -14 LUFS
 * Tidal       -14 LUFS
 */

import type { Task, Helpers } from "graphile-worker";
import { PrismaClient } from "../../generated/prisma";
import { withAccelerate } from "@prisma/extension-accelerate";
import { getOrDownloadAsset } from "../utils/cache";
import { env } from "../config/env";
import { getS3Client } from "../utils/s3";
import { getNanoSpawn } from "../utils/nanoSpawn";
import logger from "../utils/logger";

const prisma = new PrismaClient().$extends(withAccelerate());
const ffmpegBin = "ffmpeg";

interface Payload {
  vodId: string;
}

interface AudioStats {
  lufsIntegrated: number; // LUFS-I
  lra: number;            // Loudness Range
  peak: number;           // True Peak (expressed as dBTP ceiling, e.g. -0.1)
}

export async function runFFmpeg(args: string[]): Promise<string> {
  const spawn = await getNanoSpawn();

  try {
    const result = await spawn(ffmpegBin, args, {
      stdout: 'pipe',
      stderr: 'pipe',
    });

    // success → return combined output
    return result.output;
  } catch (err: any) {
    // failure → throw with stderr
    throw new Error(err.output || err.message);
  }
}

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

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

    // True peak
    if (line === "True peak:") inTruePeak = true;
    if (inTruePeak) {
      const pMatch = line.match(/Peak:\s*(-?\d+\.?\d*)\s*dBFS/);
      if (pMatch) {
        peak = parseFloat(pMatch[1]); // no negation
        inTruePeak = false;
      }
    }
  }

  return { lufsIntegrated, lra, peak };
}


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);
}

function assertPayload(payload: any): asserts payload is Payload {
  if (typeof payload !== "object" || !payload) throw new Error("invalid payload-- was not an object.");
  if (typeof payload.vodId !== "string") throw new Error("invalid payload-- was missing vodId");
}

export default async function main(payload: any, helpers: Helpers) {
  assertPayload(payload);
  const { vodId } = payload;

  const vod = await prisma.vod.findFirstOrThrow({
    where: { id: vodId },
  });

  if (vod.audioIntegratedLufs && vod.audioLoudnessRange && vod.audioTruePeak) {
    logger.info(`Skipping analysis — vod ${vodId} already complete.`);
    return;
  }

  if (!vod.sourceVideo) {
    throw new Error(`vod ${vodId} is missing a sourceVideo.`);
  }

  const s3Client = getS3Client();
  const videoFilePath = await getOrDownloadAsset(s3Client, env.S3_BUCKET, vod.sourceVideo);
  logger.info(`videoFilePath=${videoFilePath}`);

  const results = await analyzeAudio(videoFilePath);
  logger.info(`results=${JSON.stringify(results)}`);

  await prisma.vod.update({
    where: { id: vodId },
    data: {
      audioIntegratedLufs: results.lufsIntegrated,
      audioLoudnessRange: results.lra,
      audioTruePeak: results.peak,
    },
  });
}