Implement API to Generate Captions for YouTube Video

Introduction

Before creating the API endpoint, let's make a script ready that will accept a YouTube video Id and will return the generated captions of the video. We will use OpenAI's Whisper model to generate captions from audio extracted from the YouTube video. Like many cutting-edge language models, Whisper utilizes the transformer architecture. This powerful neural network excels at understanding complex relationships between words and sequences, leading to superior accuracy and flexibility.

The model architecture separates the "understanding" and "generating" functions and based on encoder-decoder pattern. The encoder processes the input audio, extracting features and meanings. The decoder takes these features and generates the text transcript. Whisper isn't trained from scratch, it benefits from a massive dataset of diverse audio-text pairs, allowing it to generalize well to unseen examples.

For this example, we will use one of the OpenAI's YouTube videos of their OpenAI DevDay: Keynote Recap video.

Steps to follow

Let's discuss the steps that will be followed to implement the script.

1. Extract and save the audio from the given YouTube video ID in a MP3 format file.

2. Use that MP3 file to convert the audio into text.

Extract and save the audio from YouTube video ID

We will use the node package @distube/ytdl-core to extract the audio part of any public YouTube video. The @distube/ytdl-core npm package is a popular tool in Node.js for downloading videos and audio from YouTube. It provides a simple and efficient way to access YouTube content and save it locally in various formats. We will be downloading the audio of the given YouTube video and pipe it to a writeable stream so that the entire audio is saved locally as a MP3 file. This MP3 file will then be sent to OpenAI to generate text from the audio.

Let's jump into the code now.