Using PHP, my process was this:
1. Choose a playlist format. My favorite playlists are Windows Media Player WPL files, which use the SMIL subtype of XML. There are tons of other types of playlists. Songbird and Winamp both use M3U, for example. Unfortunately, most playlist file types, including M3U, are not as "smart" as WPL files, in that they want the exact path to a single song on a user's computer, rather than just an artist name or song title. WPL files will take an artist or song name and give you a playlist of everything in your library that matches. I don't understand why Songbird and Winamp don't handle WPL or SMIL files (yet?). After I figured out which playlist format I wanted, I right-clicked a WPL file I'd made, opened it in Notepad, and used it to cut and paste the top, bottom, and repeating bits of the playlist code where needed in the following steps.
2. Find a source of artists or song names you want in your playlist. The best way was to use an RSS feed, but for my iLike and last.fm tag playlist makers, I scraped the source code of some web pages, which is messy, but it works. You can also offer a way to paste in or upload a list of artists.
3. Write an HTML form (called, for example, input.html) that takes user input (like a last.fm username) to get the source you want. The "Submit" button on the form will take you to your playlist making code (playlistmaker.php, for example).
4. Write code to convert your input (such as a last.fm username) into a URL to an XML or HTML file and get that file ready to be used. For example:
$handle = fopen("http://ws.audioscrobbler.com/1.0/user/".$username."/topartists.txt?type=overall", "r");
5. Write code to make an array of only artists or song names using your source. The exact code will vary depending on the source of artists or song names. This is the trickiest part, and I'd give examples of how I've done it, but it's different nearly every time, and I'm sure my ways are not especially elegant. One thing I'd like to do better is parsing the actual XML instead of finding where the artists turn up in the array and using numeric indices to grab the artists or song names.
6. Create a variable that will contain the entire text you want in the playlist file ($wpl, for example). Paste in the top bit of the playlist text. For a WPL file:
$wpl = "<?wpl version=\"1.0\"?>
<smil>
<head>
<meta name="\" content="\">
<title>".$username."</title>
</head>
<body>
<seq>
<smartplaylist version="\">";
7. Write a loop that adds the section of the playlist that repeats for each artist or song name to your playlist variable ($wpl., for example). Concatenate in the artist or song name variable. Make sure you convert HTML characters, as ampersands will render your playlist utterly worthless. For example, where the artist names are in $data[2]:
while ($data = fgetcsv($handle, 1000, ",")) {
$wpl.="<querySet>
<sourceFilter id=\"{4202947A-A563-4B05-A754-A1B4B5989849}\" name=\"Music in my library\">
<fragment name=\"Album Artist\">
<argument name=\"condition\"<Contains>/argument>
<argument name=\"value\">" . htmlspecialchars($data[2]) . "</argument>
</fragment>
</sourceFilter>
</querySet>";
}
8. Finish off your playlist text variable by pasting in the end text of the playlist variable (again, $wpl.). For a WPL file:
$wpl.="
</smartPlaylist>
</seq>
</body>
</smil>";
9. Create a new file containing your playlist variable text as follows:
$handle = fopen("filename.wpl","w");
10. Offer a link to download the new file.
11. Try it out!
Optional tweaks:
12. WPL playlist files offer you the option of finding an artist name that "Contains" the word "Bell" (for example), or finding an artist that "Is" the word "Bell." After the band "Bell" made Belle and Sebastian turn up in a festival playlist I made (oh, the brief crushing excitement), I added a conditional so that if the artist name is 5 characters or shorter, I use "Is", and if it's longer, I use "Contains". It's still inexact, and it's an area I'd like to improve. Handling "The" (Pixies, Beatles, Raveonettes) is another thing I'd like to work out at some point. Here's an example of one of my conditionals where the artist names are in $data[2]:
while ($data = fgetcsv($handle, 1000, ",")) {
$limit=6;
$num=count($data[2]);
for ($i=0;$i<$num;$i++) {
$len[$i]=strlen($data[2]);
if ($len[$i]<$limit) {
$wpl.="<querySet>
<sourceFilter id=\"{4202947A-A563-4B05-A754-A1B4B5989849}\" name=\"Music in my library\">
<fragment name=\"Album Artist\">
<argument name=\"condition\">Is</argument>
<argument name=\"value\">" . htmlspecialchars($data[2]) . "</argument>
</fragment>
</sourceFilter>
</querySet>";
}
else {
$wpl.="<querySet>
<sourceFilter id=\"{4202947A-A563-4B05-A754-A1B4B5989849}\" name=\"Music in my library\">
<fragment name=\"Album Artist\">
<argument name=\"condition\"<Contains>/argument>
<argument name=\"value\">" . htmlspecialchars($data[2]) . "</argument>
</fragment>
</sourceFilter>
</querySet>";
}
}
}
13. Greasemonkey! Using a tiny bit of Javascript, you can put a link to your playlist making code on relevant source pages. Clicking this link will give you the option to look at one of my Greasemonkey scripts. You'll especially want to change:
- @include to reference the page you'd like to put a link on.
- The link to the script that makes your playlist.
- @name
- @namespace
- Colors (I'm using last.fm grey. Meh.)
You can grab the username for the last.fm URL they came from by putting this at the top of your playlist maker script (playlistmaker.php, for example):
$url = getenv("HTTP_REFERER");
$elements=explode("/", $url);
unset($url);
$username=$elements[4];
unset($elements);
Here's a zip folder with code for the input form and playlist maker, as well as a Greasemonkey playlist maker for a last.fm listener's most-played artists. This was one of the first things I did when I was learning PHP, so it's far, far, far from perfect. But feel free to use any bits of it you like. I'm not litigious.
I am crawling up a learning curve (Drupal) myself right now, but if you have questions or suggestions, comments are open.
For anyone more interested in making playlists than playlist-maker scripts, my playlist makers are here.
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