SWFSound.
Just an example of how to use this class. It just cerates a serie of three images with a background sound in each one of them.
<?php
$movie = new SWFMovie();
$movie->setRate(1);
$img1 = new SWFBitmap(fopen('./tmp/img1.jpg', 'rb'));
$img2 = new SWFBitmap(fopen('./tmp/img2.jpg', 'rb'));
$img3 = new SWFBitmap(fopen('./tmp/img3.jpg', 'rb'));
$snd1 = new SWFSound(fopen('./tmp/1.wav', 'rb'), SWF_SOUND_22KHZ|SWF_SOUND_16BITS|SWF_SOUND_MONO);
$snd2 = new SWFSound(fopen('./tmp/2.wav', 'rb'), SWF_SOUND_22KHZ|SWF_SOUND_16BITS|SWF_SOUND_MONO);
$snd3 = new SWFSound(fopen('./tmp/3.wav', 'rb'), SWF_SOUND_22KHZ|SWF_SOUND_16BITS|SWF_SOUND_MONO);
$s = $movie->startSound($snd1);
$s->loopcount(1);
$s->loopinpoint(1 * 100);
$i = $movie->add($img1);
$i->setDepth(1);
$movie->nextFrame();
$s = $movie->startSound($snd2);
$s->loopcount(1);
$s->loopinpoint(1 * 100);
$i = $movie->add($img2);
$i->setDepth(2);
$movie->nextFrame();
$s = $movie->startSound($snd3);
$s->loopcount(1);
$s->loopinpoint(1 * 100);
$i = $movie->add($img3);
$i->setDepth(3);
$movie->nextFrame();
$movie->setBackground(0xff, 0xff, 0xff);
$movie->setDimension(130, 97);
$movie->add(new SWFAction("gotoFrame(0); play();"));
$movie->nextFrame();
$movie->save("bw.swf");
?>