将流从 Fluent-ffmpeg 传递到 Google Cloud Storage

Question

Is there a way to pass a stream from Fluent-mmpeg to Google Cloud Storage? I'm trying to allow the user to upload any kind of media (audio or video), and I want to convert it to flac before uploading it to GCS.

I'm using a few middlewares on my route, such as:

routes.post(
  '/upload',
  multer.single('audio'),
  ConvertController.convert,
  UploadController.upload,
  FileController.save,
  (req, res, next) => res.send('ok')
);

I was able to stream from Multer to Fluent-mmpeg and save to a file using this code on ConvertController:

async convert(req, res, next) {
    ffmpeg(streamifier.createReadStream(req.file.buffer))
      .format('flac')
      .output('outputfile.flac')
      .audioChannels(1)
      .on('progress', function(progress) {
        console.log(progress);
      })
      .run();
  }

But I would like to use.pipe() to pass it to UploadController, where I would then upload to GCS:

class UploadController {
  async upload(req, res, next) {
    const gcsHelpers = require('../helpers/google-cloud-storage');
    const { storage } = gcsHelpers;

    const DEFAULT_BUCKET_NAME = 'my-bucket-name';

    const bucketName = DEFAULT_BUCKET_NAME;
    const bucket = storage.bucket(bucketName);
    const fileName = `test.flac`;
    const newFile = bucket.file(fileName);

    newFile.createWriteStream({
      metadata: {
        contentType: file.mimetype
      }
    })

    file.on('error', err => {
      throw err;
    });

    file.on('finish', () => console.log('finished'));
  }

The problem is that I cannot find anywhere explaining how I can pass down a stream to the next middleware.

Is it possible?

Answer 1

Attach your ffmpeg stream to the req object, and then you can pass your ffmpeg stream to the next middleware using the next() . Then you can pipe the stream to your GCS file.

Something like this:

// ConvertController
req.ffpmegStream = ffmpeg(streamifier.createReadStream(req.file.buffer))
  .on('finish', next)

// UploadController
req.ffmpegStream.pipe(newFile.createWriteStream())

Reference:

• Passing variables to the next middleware using next() in Express.js
• File#createWriteStream