Creating Readstream from Audio Buffer for Whisper API

Hey everyone,

I’m using the API to transcribe an uploaded audio file. I’ve got a solution working where I save the uploaded file locally and then use the function fs.createReadStream() to provide the file as a readstream to the API.

Although I want to prevent saving anything locally; I need to somehow convert the audio buffer into a readstream that OpenAI accepts.

Previous to the recent updates in November 2023 the solution seemed to be to hack around an issue with the API by using the following method:

const audioReadStream = Readable.from(audioFile.buffer); 
audioReadStream.path = `audio.wav`;

const response = await{
    file: audioReadStream, 
    model: 'whisper-1',

adding the .path to the readstream. Nevertheless this does not work for me so I’m guessing OpenAI fixed this in their update.

Please please can someone help me out with this? How can I go from a buffer to an appropriate input to the whisper API without saving anything locally?

Thanks so much in advance!

Not sure if you every got this solved but the solution for me was using this

import { toFile } from 'openai/uploads';

Pass your buffer into that function and use the name parameter to ensure the file extension is correct.


If u use the toFile() and u got some error, it might be the missing name:

Initially, I was doing this:

 const file = await toFile(Buffer.from(data));

Somehow, I managed to make it work without the library, and then I asked myself: WHY?!

Here is the reason:

 const file = await toFile(Buffer.from(data), 'audio.mp3');

This worked for both the node.js library and a pure fetch request.

I’m not really sure why, but I believe it has to do with the “name” inference in the “toFile()” method:

@param name — the name of the file. If omitted, toFile will try to determine a file name from bits if possible.

Note it says Try

When I manually added the name and type, it worked properly. However, when I removed it, I started getting nonstop errors.


Thanks, indeed the toFile method helps us to convert the buffer, here is the piece of code updated for a usage with latest node (using Readable instead of Buffer from)

import { Readable } from "stream";
import OpenAI from "openai";
import { toFile } from "openai/uploads";


const convertedFile = await toFile(Readable.from(data), name);
const response = await openai.files.create({
  file: convertedFile,
  purpose: "assistants",