Save Internet Audio Streams to MP3s

Posted on January 21st, 2009 in General,Linux System Administration,PHP,Programming by Brandon

I’ve got a couple of radio programs that I like to listen to. The only problem is that I rarely am able to listen to them live. I was wishing that somebody made a good DVR-like device for the radio, but after some thought figured out a way to do it on my own using internet audio streams that most radio stations now have available.

Googling for instructions on how to save Internet audio streams will return a lot of semi-workable but mostly garbage instructions. The best set of instructions I found was at Instructables.com where the basic concept is to use the command-line mplayer to save the stream as a wave file, then use lame to convert it to an MP3.

The instructables tutorial had several downfalls though. First, it is not able to stop mplayer on its own, so it uses a second cron job to kill the original mplayer command – a little to crude for my taste. Secondly, and more importantly, you have to know the exact stream URL which is not easy to identify from most internet radio websites. They tend to hide the actual stream source behind layers of javascript so that their web-based players can synchronize ads and such while listening to the streams.

I created some PHP code that automates this process and makes it pretty simple. The basic streamsave class provides functions for downloading the wave file and converting it to an MP3. I then extend that class for specific radio stations that I want to save. The extended class provides functions that run through all of the javascript garbage to get to the actual stream source.

Using those classes, this simple script now saves my stream to an MP3 file and emails me the location when it is done:

<?php
require_once dirname(__FILE__).'/ss_640wgst.class.php';

$streamsave = new ss_640wgst();

$streamsave->stream_url = $streamsave ->getStreamURL();
$streamsave->seconds = 60 * 60; // One hour

// This saves the stream to a temporary wav file
$streamsave->save_stream();

// Now encode it to an mp3
$output_file = "/tmp/some_directory/some_program_".date('Y-m-d-His').'.mp3';
$streamsave->encode_to_mp3($output_file);

// Delete the large wav file
unlink($streamsave->wavfile);

// And tell me that the file was saved
echo "File saved (if all went okay) to {$streamsave->mp3file}\n\n";
mail('you@yourdomain.com', 'Audio File Saved', "File saved to {$streamsave->mp3file}");

// It would be cool to create a podcast XML file here that contains your new file

?>

Downloads

The abstract class file: streamsave.class.php
The extended class specifically for 640 WGST in Atlanta: ss_640wgst.class.php

I’ve created the extended classes for stations that are useful for me. If there seems to be any interest, I can work on developing that a bit more to make it more generalized and work for more radio stations.

One Response to 'Save Internet Audio Streams to MP3s'

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  1. Rich said,

    on March 3rd, 2009 at 9:39 am

    Excellent! I had previously used the old mplayer method but could no longer find a static URL for WGST. After beating my head against this problem for 2 days I happened to find your solution, and it works great.

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