audio.html

<audio controls src="your-cfURL-from-server">
  <track kind="captions" />
  Your browser does not support the
  <code>audio</code> element.
</audio>

r2-mp3.js

import { R2 } from 'node-cloudflare-r2';
import ffmpeg from 'fluent-ffmpeg';
import ffmpegPath from 'ffmpeg-static';
import multer from "multer";
import express from "express";

const r2AccountId = process.env.R2_ACCOUNT_ID;
const r2AccessKeyId = process.env.R2_ACCESS_KEY_ID;
const r2SecretAccessKey = process.env.R2_SECRET_ACCESS_KEY;
const r2BucketName = process.env.R2_BUCKET_NAME;
const r2Endpoint = `https://${r2AccountId}.r2.cloudflarestorage.com`;

ffmpeg.setFfmpegPath(ffmpegPath);

const audioStorage = multer.diskStorage({
  destination: (req, file, cb) => {
    cb(null, "uploads/");
  },
  filename: (req, file, cb) => {
    cb(null, `${Date.now()}-${file.originalname}`);
  },
});

const fileFilter = (req, file, cb) => {
  const allowedTypes = [
    "audio/m4a",
    "audio/mp4",
    "audio/mpeg",
    "audio/mp3",
    "audio/wav",
    "audio/ogg",
    "audio/webm",
    "image/png",
    "image/jpeg",
  ];
  const mimeType = mime.getType(file.originalname);

  if (allowedTypes.includes(mimeType)) {
    file.mimetype = mimeType; // Manually set the correct mimetype
    cb(null, true);
  } else {
    cb(
      new Error(
        `Unsupported file format. Supported formats: ${allowedTypes.join(", ")}`
      ),
      false
    );
  }
};

const audioUpload = multer({ storage: audioStorage, fileFilter });

// ...


const r2 = new R2({
  accountId: r2AccountId,
  accessKeyId: r2AccessKeyId,
  secretAccessKey: r2SecretAccessKey,
});

const bucket = r2.bucket(r2BucketName);

bucket.provideBucketPublicUrl('your-pub-bucket');
console.log(await bucket.exists()); // true


/**
 * Converts an m4a file to mp3.
 * 
 * @param {string} inputFilePath - The path to the input m4a file.
 * @param {string} outputFilePath - The path to save the converted mp3 file.
 * @returns {Promise<void>} - A promise that resolves when the conversion is complete.
 */
function convertM4aToMp3(inputFilePath, outputFilePath) {
  return new Promise((resolve, reject) => {
    ffmpeg(inputFilePath)
      .toFormat('mp3')
      .on('end', () => {
        console.log('Conversion finished!');
        resolve();
      })
      .on('error', (err) => {
        console.error('Error during conversion:', err.message);
        reject(err);
      })
      .save(outputFilePath);
  });
}

server.post("/transcribe", audioUpload.single("audio"), async (req, res) => {
  try {
    const file = req.file;
    if (!file) {
      return res.status(400).json({ error: "Audio file is required" });
    }
    
    let filePath = file.path;

    // if file is m4a, convert to mp3
    if (file.originalname.endsWith('.m4a')) {
      const outputFilePath = file.path.replace('.m4a', '.mp3');
      await convertM4aToMp3(file.path, outputFilePath);
      filePath = outputFilePath;
    }
    
    const content = fs.readFileSync(filePath);
    const uploadResult = await bucket.upload(content, `${Date.now()}_${filePath.replace('uploads/', '')}`);

    const cfURL = uploadResult.publicUrl;

    const transcription = await transcribe(file.path); // im using openai whisper and gpt 4o to transcribe my audio to text

    // delete the file after processing
    fs.unlinkSync(filePath);
    if (file.path !== filePath) {
      fs.unlinkSync(file.path);
    }

    res.json({ transcription, cfURL });
  } catch (err) {
    console.error(err);
    // unlink file if it exists
    fs.unlinkSync(filePath);
    if (file.path !== filePath) {
      fs.unlinkSync(file.path);
    }
    res.status(500).json({ error: err.message });
    
  }
});