We will need to convert the recording, to mp3, in real time, in the browser. Simply saving the wav file and then converting it will not do. The solution to this? Well let’s convert the wav file to mp3. The problem with wav is that the files are non-compressed, therefore they take up a lot of space on the disk, just 1 minute of recording can take as much as 10 Megabytes. Recorder.js implements the capture audio functionality and saves it in wav format using getUserMedia. The starting point for the whole process of recording mp3 is represented by Matt Diamond’sRecorder.js, a plugin developed in JavaScript for recording/exporting the output of Web Audio API nodes. The Recorder.js Library and libmp3lame.js Library Also for a thorough reference guide you can check the Mozilla Developer Network article. For a more detailed look on the history and development of the API you can check the html5rocks article. The best support can be found in Chrome, followed shortly by Firefox. We will get to the ‘how’ soon, but first off you will have to remember that this API is still in development and is not supported by all browsers and there is no standardized version yet. Using the getUserMedia() API, you can capture raw audio input from your microphone. In this article we will be focusing on audio capture and more specifically on capturing audio from the microphone and encoding it to MP3. With the continuous advancements of HTML 5, audio/video capture using only the browser has reached a turning point where it is possible to record but only on specific browsers.