Mp3 and TimerEvent not in sync

Question

Last night a buddy of mine who I make music with was asking
me if I could get objects to move in flash in sync with the sounds.
I said I might be able to, and figured it would be good to load an
mp3, a simple hihat called hihat.mp3. My idea is to set up a
TimerEvent that calls a function 'hitHiHat()' every 250
milliseconds. Problem is, when I run the program, the sound of the
mp3 is not in sync. I thought this might be a bad idea because the
TImerEvent might not be very accurate, but I remember reading
somewhere that the TimerEvent is VERY accurate. If it's not, I
definitely can't do what I'm trying to do, because the idea is to
have multiple instruments playing. If it's not the TimerEvent, I
thought that maybe it's the _sound.play() function that is lagging,
or that maybe there is a conflict with the mp3 already playing when
the hitHiHat function is called. Please let me know if I could do
something to make this program have a bit more rhythm, or if it's
just a bad idea altogether (code below). THANKS!
package {
import flash.display.Sprite;
import flash.events.Event;
import flash.events.MouseEvent;
import fl.transitions.Tween;
import flash.net.URLLoader;
import flash.net.URLRequest;
import flash.text.TextField;
import flash.display.StageAlign;
import flash.display.StageScaleMode;
import flash.xml.*;
import flash.display.Loader;
import flash.filters.DropShadowFilter;
//import kurt.classes.Console;
import flash.utils.Timer;
import flash.events.TimerEvent;
import flash.media.Sound;
import flash.media.SoundChannel;
[SWF(backgroundColor="0x000000")]
public class gentlemansound extends Sprite {
private var tf:TextField = new TextField();
private var circle:Sprite;
private var tempo:Timer;
private var _sound:Sound;
private var urlReq:URLRequest;
private var soundChan:SoundChannel;
private var needsToPlay:Boolean;
public function gentlemansound() {
init();
private function init():void {
needsToPlay = true;
stage.scaleMode = StageScaleMode.NO_SCALE;
stage.align = StageAlign.TOP_LEFT;
circle = new Sprite();
circle.graphics.beginFill(0xFFFFFF);
circle.graphics.drawCircle(100,400,40);
circle.graphics.endFill();
addChild(circle);
_sound = new Sound();
urlReq = new URLRequest("sounds/hihat.mp3");
_sound.load(urlReq);
_sound.addEventListener(Event.COMPLETE, startHiHat);
tempo = new Timer(250);
tempo.addEventListener(TimerEvent.TIMER, hitHiHat);
tf.width = 400;
tf.height = 200;
tf.border = true;
tf.multiline = true;
tf.x = 10;
tf.y = 20;
//tf.x = stage.stageWidth / 20;
//tf.y = stage.stageHeight / 20;
tf.text = "blah blah blah blah blah blah blah blah blah blah
blah blah blah blah";
//addChild(tf);
private function startHiHat(event:Event):void {
tempo.start();
private function hitHiHat(event:TimerEvent):void {
if (needsToPlay == true) {
soundChan = _sound.play();
needsToPlay = false;
soundChan.stop();
soundChan = _sound.play();

Answer 1

the timer function (along with setInterval and every other
loop in flash) is inaccurate and very much dependent on local
system speed. in short, there is no loop in flash suitable for
synch'g sound and anything else. the ear it too sensitive to even
small mis-timings.
you can however, create a self-correcting loop based on
getTimer() (which is as accurate as the local system clock) which
can maintain a small error tolerance. even this, however, may not
be satisfactory for your purposes and you may need to synch sound
and animation in a flv.