Hacking at 0300

As I wrote, I'm using Amazon S3 to store files that are too expensive to keep on my web server, with the plan of having frequently-updated files on the server and relatively constant stuff on S3. The address for my S3 server is bililite.s3.amazonaws.com, which is stored in the global variable $_SERVER['CDN'].

So to include a file, I would do:

$filename = '/toinclude.php';
if (file_exists($_SERVER['DOCUMENT_ROOT'].$filename)){
  $filename = $_SERVER['DOCUMENT_ROOT'].$filename;
}else{
  $filename = $_SERVER['CDN'].$filename;
}
include ($filename);

Which I use often enough to want to generalize it into a class.

Since I started using nearlyfreespeech.net 3 months ago, I've been very pleased. Getting them to set up access with a private key was straightforward and the email support person was prompt, helpful and friendly. The only downsides are the safe mode restrictions, which I have been easily able to work around, and the expensive storage ($1/MB/month), which would add up quickly with all the icons and fonts I'm serving with the webservices.

So I put them onto Amazon's S3 at bililite.s3.amazonaws.com with the intent of using that like a Content Delivery Network (though it isn't really unless I pay for CloudFront as well)—static, large files should come tranparently from S3 while the dynamic site runs on NFS.net.

I do this with a bit of .htaccess hackery. It's harder to create or modify files on S3, so files that are in active developement are on the webserver. I want to serve those files if they exist. Only if the desired files do not exist do I want to get them from S3. Unfortunately, NFS.net does not support mod_proxy, so the redirecting is not transparent (and we can't do things that require same-origin security). But for images and the like, this works:

SetEnvIf Request_URI . CDN=http://bililite.s3.amazonaws.com
RewriteEngine On
RewriteBase /
RewriteCond %{REQUEST_FILENAME} !-f
RewriteCond %{REQUEST_URI} ^/(images|inc|fonts)/
RewriteRule . %{ENV:CDN}%{REQUEST_URI}

Line 1 creates a variable named CDN. The directive SetEnv would be more natural to use as SetEnv CDN http://bililite.s3.amazonaws.com, but URL rewriting is done before SetEnv runs. The newer SetEnvIf runs early enough for the variable to be used for rewriting, but it's conditional, so we use a dummy condition: REQUEST_URI ., which means "If the requested URI matches any character"

Line 4 tests whether the requested file exists on the server. Only if it does not exist (!-f) is the next line tested, which is whether the file is in any of the CDN directories.

If it is to be redirected, create the new URL by concatenating the CDN variable with the requested URI, which does not contain the protocol or hostname. Thus http://bililite.com/images/silk/add.png has a REQUEST_URI of /images/silk/add.png and the rewritten URL is http://bililite.s3.amazonaws.com/images/silk/add.png.

The advantage of setting a variable in the .htaccess (aside from having the "magic constant" at the top of the file") is that this is passed to the PHP code as imagecreatefrompng($_SERVER['CDN'].'/images/silk/add.png'). So the name of the S3 server is written in just one place, with no need to change multiple files if it changes.

Download the code.

Demo.

Download the WP Audio Player Standalone.

So the rabbi asked me to add the ability to play the audio on the taamim page (basically, a long list of short MP3's) directly on the page, rather than click the link to open a new page. No problem, right? We're living in an HTML5 world, so I should be able to do:

$('a[href$=mp3]').each(function(){
  $('<audio>').attr({src: this.href, controls: 'controls'}).insertBefore(this);
});

And everything ought to work: browsers that can't handle <audio> elements get nothing, modern browsers get a modern audio player. Nice progressive enhancement.

But of course, it's not that easy. Webkit (Chrome, Safari) supports MP3 playing, but Firefox does not (and won't), and Internet Explorer only does for IE9 and up, and I have to support Windows XP and IE8 (source; consistent with my experimentation). I don't like the <embed>ed players, so I'll go with Flash. I like the player that Language Log uses, and viewing the source tells me that's WPAudioplayer, which has a standalone version that requires just two files, the 11-kb swf file and a 12-kb javascript file.

To use it, include the javascript with a <script> element and initialize the player with AudioPlayer.setup('/path/to/player.swf', {width: 100}); where 100 is the desired width of the player in pixels (it's constant for every player on the page and it's a mandatory option). Then, each player is implemented by replacing an existing element, identified by id: AudioPlayer.embed(id, {soundFile: '/path/to/soundfile.mp3'});.

Of course, iOS won't run Flash, so I still need to use the <audio> element there. So I need to detect if the audio element works, and if not, insert the Flash substitute. Browsers that can't handle either get a blank spot.

Putting it together into a plugin:

(function($) {

var uid = 0;
var init = function (swf, width){
	AudioPlayer.setup(swf, {width: width});
	init = $.noop;
}
$.fn.inline_mp3 = function(swf){
  return this.each(function(){
		var id = 'audioplayer_'+(uid++);
		var player = $('<audio>').attr({
			src: this.href,
			controls: 'controls',
			id: id
		}).insertBefore(this);
		// audio.canPlayType test from http://diveintohtml5.com/everything.html#audio-mp3
		if (!(player[0].canPlayType && player[0].canPlayType('audio/mpeg;').replace(/no/, ''))){
			init (swf, player.width());
			AudioPlayer.embed(id, {soundFile: this.href});
		}
	});
};
})(jQuery);

It uses a unique number to assign an id to each element, and lazy-initializes the Flash player. The player should be styled with a given width (since IE8 doesn't have a default <audio> size):

audio {
	width: 80px; 
	display: inline-block;
}

And use it:

$('a[href$=mp3]').inline_mp3('/path/to/player.swf');

And there are lots of other packages of html5/Flash fallback audio players but this is small and easy enough for me to understand.