How can I get amplitude data from an MP3 file?

Question

I am trying to use html5 and javascript to get the amplitude (and other components) of an mp3. Any libraries to help?

Answer 1

First you need to divide the problem into real-time playback and non-linear amplitude, etc.

For live playback, you can use the web audio API

https://dvcs.w3.org/hg/audio/raw-file/tip/webaudio/specification.html

Example for bits

https://beatdetektor.svn.sourceforge.net/svnroot/beatdetektor/trunk/core/js/beatdetektor.js

For non-linear non-real-time access, there are two ways:

If you allow server-side processing, you can write your proxy server that sends data to the Echo Nest servers and receive information through the Echo Next Remix API

Removing Beats from MP3 Music Using Python

If you want to avoid server-side processing at all, you need to decode MP3 in pure Javascript in order to access the raw audio in real time

https://github.com/devongovett/mp3.js

Then you need to apply the necessary filters to the original audio data to extract the information you need. This is a signal processing problem and is not directly related to Javascript programming. If you define in more detail what data you want after people can help you with the appropriate Javascript libraries, for example, for fast Fourier transform.