AS3 sound.extract（）的波形 [英] AS3 sound.extract() for waveform

问题描述

早上好！

我试图创造一个MP3视觉波形。在code我已经包括了被称为对MP3的成功加载。我打算只提取了几个重要的样本从声音来创建波形，而不是提取整个声音转换为bytearray。即使在一个良好的机器，提取整首歌曲可能会导致闪存冻结了3-5秒（或更长！）。对于我而言，这是不可行的。

I'm trying to create a visual waveform for an MP3. The code I've included is called on successful load of the MP3. I intend to extract just a few important samples from the sound to create the waveform, rather than extract the entire sound into a bytearray. Even on a good machine, extracting an entire song can cause flash to freeze up for 3-5 seconds (or longer!). For my purposes, this isn't feasible.

不幸的是，code我有如下未能出示任何数字。如果我提取整首歌曲它的功能，但提取的只是关键点是给我什么。是否执行提取物为未来提取的声音对象的其余部分无效？如果是这样，有一些解决这个方式，将不会冻结闪光时间的提取物中长时间？

Unfortunately, the code I've got below is failing to produce any numbers. If I extract the entire song it functions, but extraction of just the key points is giving me nothing. Does performing an extract make the remainder of the sound object invalid for future extracts? If so, is there some way around this that won't freeze flash for an extended period of time during the extract?

从的code，其余一些重要的变量：

Some important variables from the rest of the code:

waveFor​​mWidth：波形精灵的静态宽度
。 waveFor​​mHeight：波形精灵的静态高度
。 歌曲：我将使用创建波形声音对象

waveFormWidth: static width of the wave form sprite.
waveFormHeight: static height of the wave form sprite.
song: sound object that I'll be using to create the wave form.

    public function mapWaveForm(e:Event = null):void
    {

        // Clear the wave form sprite
        waveForm.graphics.clear();
        waveForm.graphics.lineStyle(0, 0x000000, 1);

        // Storage for the wave form bit data
        var byteOutput:ByteArray;
        var leftPeakSize:Number;
        var rightPeakSize:Number;
        var songTotalSamples:int;
        var thisSample:int;

        byteOutput = new ByteArray();

        // How many samples?
        songTotalSamples = (song.length * 44.1);

        // Loop for the wave form width
        for (var peakCount:int = 0; (peakCount < waveFormWidth); peakCount++)
        {

            // Get info at each peak.
            thisSample = Math.floor(songTotalSamples * (peakCount / waveFormWidth));
            song.extract(byteOutput, 1, thisSample);
            byteOutput.position = 0;
            trace(thisSample, byteOutput.readFloat());

            leftPeakSize = byteOutput.readFloat() / 1.27;
            rightPeakSize = byteOutput.readFloat() / 1.27;

            // Turn those peaks into something usable.
            leftPeakSize = leftPeakSize * (waveFormHeight * .5);
            rightPeakSize = rightPeakSize * (waveFormHeight * .5);

            // Make the left channel line
            waveForm.graphics.moveTo(peakCount, (waveFormHeight * .5));
            waveForm.graphics.lineTo(peakCount, (waveFormHeight * .5) - leftPeakSize);

            // Make the right channel line
            waveForm.graphics.moveTo(peakCount, (waveFormHeight * .5));
            waveForm.graphics.lineTo(peakCount, (waveFormHeight * .5) + rightPeakSize);


        }

    }

感谢您的帮助家伙！

Thanks for your help guys!

推荐答案

有关它的价值，我只是工作的确切同样的事情，我只是得到了它的一些研究工作后。我似乎无法得到它与WAV文件的工作，但是这是compatable与所有类型的MP3文件。这是我结束了：

For what it's worth, I was just working on the EXACT same thing and I just got it working after some research. I cannot seem to get it to work with WAV files, but this is compatable with MP3 files of all types. This is what I ended up with:

var IMAGE_SIZE:int = new int(600); // Final width of image
var IMAGE_DEPTH:int = new int(5); // How many passes per pixel of image
var RESOLUTION:int = new int(IMAGE_SIZE * IMAGE_DEPTH);
var DRAW_AMPLITUDE:int = new int(150); // pixel height of max volume line

var waveForm:Shape = new Shape();

var mp3File:Sound = new Sound();
mp3File.load(new URLRequest("audio.mp3"));
mp3File.addEventListener(Event.COMPLETE, parseSound);

function parseSound(e:Event):void {
    var soundBytes:ByteArray = new ByteArray();
    for (var i:int=0; i<RESOLUTION; i++) {
        mp3File.extract(soundBytes, 1, Math.floor((mp3File.length*44.1)*(i/RESOLUTION)));
        soundBytes.position = 0;
        while (soundBytes.bytesAvailable > 0) {
            var tmpNum:Number = new Number();
            tmpNum += soundBytes.readFloat();
        }
        drawWave(i, tmpNum);
        soundBytes.clear();
    }
    this.addChild(waveForm);
    trace("--DONE--");
}

function drawWave(i:Number, amp:Number):void {
    var pixX:Number = new Number(Math.floor(i/IMAGE_DEPTH));
    var pixY:Number = new Number((amp*DRAW_AMPLITUDE)/2);
    waveForm.graphics.lineStyle(1, 0x0, (1.2/IMAGE_DEPTH));
    waveForm.graphics.moveTo(pixX, ((DRAW_AMPLITUDE/2)-pixY));
    waveForm.graphics.lineTo(pixX, ((DRAW_AMPLITUDE/2)+pixY));
}

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