Audio Resampling in Node.js — JavaScript

In the age of digital media, audio files have become an integral part of our lives. From music to podcasts, we often find ourselves needing to store these files in our web applications. However, with audio files often being large in size, storage can quickly become a concern. One solution is to resample the audio file, which involves altering the sampling rate to reduce its size. While this can be an effective solution, it’s important to consider the potential trade-offs in audio quality. In this context, we’ll explore how resampling works using JavaScript for web and mobile app concerns.

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Sometimes we are required to save audio files in our web app. At the same time we may or may not concerned with the quality of sound or we are really concerned with space it requires. Meanwhile some audios are like too large due to their format. For example, wav files are uncompressed and thus are larger in size than mp3 files. In most of the cases we are not really concerned with the file format but only with its content and thus converting wav to mp3 is a good choice to save storage. Else than that there is another way called resampling where we alter bit depth and frequency of the audio file. There are many purposes of resampling but here we will do that to save more storage. Without any further discussion let’s see how it works.
Before using the below code you must have installed ffmpeg tool on your system. Here is the quick guide to install ffmpeg on Windows.

Step-by-Step Guide: How to Install FFmpeg on Windows and Unleash Your Multimedia Potential

Assuming that you have successfully installed ffmpeg tool on your system, let's dig into the code.

• Import required modules

const path = require("path");
const ffmpeg = require("fluent-ffmpeg");

You have to install fluent-ffmpeg module using this command.

npm i fluent-ffmpeg

• Create a function to resample audio file

Here, the fluent-ffmpeg will do the main job. i.e. resampling, while in audioFrequency() method we will pass our desired sample rate and then finally save() method will save the file to the given path. This conversion operation returns a lot of information about the operation that's why we are saving it in result variable in case we want to perform further operations based on that information.

const compressAudio = async (inputFile, outputFile) => {
  const result = ffmpeg(inputFile).audioFrequency(16000).save(outputFile);
  if (result) {
    console.log("Audio compressed successfully");
  }
};

• Calling the function

Now we have to call it by giving two arguments. i.e. the first one will be the path to input file and the second one will be the path to our output file.

let inputFile = "path/to/source_file.wav";
let dir_name = path.dirname(inputFile);
let file_name = path.parse(inputFile).name;

let outputFile = dir_name + "\\" + file_name + ".mp3";

await compressAudio(inputFile, outputFile);

That’s all. You will see that in your given directory a new file is created.

In conclusion, resampling can be a useful tool for reducing the size of audio files and optimizing storage in web applications. However, it’s important to consider the potential trade-offs in audio quality, particularly if the original file is of high quality. Before resampling, it’s recommended to assess the specific needs of your web application and determine if resampling is the best solution. By being mindful of these considerations, we can ensure that we’re optimizing storage without sacrificing audio quality in our digital media projects.

Originally published at https://dev.to on April 7, 2023.