Flex4制作一个带波形的MP3播放器的例子

下面是一个使用Flex制作的MP3播放器，除了音量调节，左右声道调节，播放暂停外。还会通过对声音的采样进行动态波形图的绘制。效果图如下：

代码如下

    

        flash.display.Graphics;

            import flash.events.TimerEvent;

            import flash.filters.GlowFilter;

            import flash.media.Sound;

            import flash.media.SoundChannel;

            import flash.media.SoundMixer;

            import flash.media.SoundTransform;

            import flash.net.URLRequest;

            import flash.utils.Timer;

             

            import mx.events.SliderEvent;

            //声音对象与声音控制对象

            private var sound:Sound;

            private var soundChannel:SoundChannel;

            //播放位置和播放状态

            private var position:Number = 0;

            private var isPlaying:Boolean = false;

            //定时器

            private var soundTimer:Timer = new Timer(100,0);

             

            private function initApp():void{

                //还没加载完，按钮不可用

                btn_play.enabled = false;

                btn_pause.enabled = false;

                //左右声道均衡

                slider_pan.value = 0;

                //音量最大

                slider_volume.value = 1;

                //

                var 
url:URLRequest
 = new URLRequest("./music.mp3");

                 

                sound = new Sound();

                //声音加载完毕监听

                sound.addEventListener(Event.COMPLETE, completeHandler);

                //声音播放完毕监听

                sound.addEventListener(Event.SOUND_COMPLETE,mp3EndHandler);

                sound.load(url);

                //滑块与按钮监听

                slider_volume.addEventListener(SliderEvent.CHANGE,changeVolume);

                slider_pan.addEventListener(SliderEvent.CHANGE,changePan);

                btn_play.addEventListener(MouseEvent.CLICK,playSound); 

                btn_pause.addEventListener(MouseEvent.CLICK,pauseSound);

                //定时器添加监听

                soundTimer.addEventListener(TimerEvent.TIMER,showSoundWave);

                //定义一个发光效果，用于波形图上

                var glow:GlowFilter = new GlowFilter();

                glow.color = 0xAEB4E6;

                glow.blurY = 6;

                glow.strength = 3;

                soundWave.filters = [glow];

            }

             

            //改变音量

            internal function changeVolume(evt:SliderEvent):void{

                //得到声音的soundTransform对象

                var soundControl:SoundTransform = soundChannel.soundTransform;    

                soundControl.volume = evt.value;

                //应用新的设置

                soundChannel.soundTransform = soundControl;

            }

             

            //左右声道

            internal function changePan(evt:SliderEvent):void{

                var soundControl:SoundTransform = soundChannel.soundTransform;    

                soundControl.pan = evt.value;

                soundChannel.soundTransform = soundControl;

            }

             

            //加载完毕

            internal function completeHandler(evt:Event):void{

                btn_play.enabled = true;

                btn_pause.enabled = true;

            }

             

            //播放完毕

            internal function mp3EndHandler(evt:Event):void{

                position = 0;

                soundTimer.stop();

                isPlaying = false;

            }

             

            //开始播放

            internal function playSound(evt:MouseEvent):void{

                soundChannel = sound.play();

                isPlaying = true;

                position = 0;       

                soundTimer.start();

            }

             

            //暂停

            internal function pauseSound(evt:MouseEvent):void{

                //判断是否在播放      

                if(isPlaying){

                    position = soundChannel.position;

                    soundChannel.stop();

                    soundTimer.stop()

                }else{

                    soundChannel = sound.play(position);

                    soundTimer.start();

                }

                isPlaying = !isPlaying;

            }

             

            //显示波形

            internal function showSoundWave(evt:TimerEvent):void{

                 

                var g:Graphics = soundWave.graphics;

                //清除以前绘制对象

                g.clear();

                //接受波形数据

                var soundData:ByteArray = new ByteArray();

                SoundMixer.computeSpectrum(soundData,true,0);

                //线条样式

                g.lineStyle(1,0x006699,1);

                //i每次加2，读取128个数据单位

                //0~255是左声道，256～512是右声道

                for(var i:Number = 0;i<256;i+=2){

                    //读取32位的浮点数

                    var n:Number = soundData.readFloat();

                    //放大32倍，看得更清楚

                    g.lineTo(i,36*n);

                    g.moveTo(i,36*n);

                }

            }

        ]]>