решил задачу. В осн. помогла статья вот эта http://www.marinbezhanov.com/web-development/14/actionscript-3-sound-extract-demystified-or-how-to-draw-a-waveform-in-flash/
но мне ее пришлось не много модифицировать, поясню свою технологию
1. размеры сцены задал жестко 600х100 пикселей. (если поменять размеры, то в коде тоже придеться хорошенько понастраивать соотношения параметров).
2. SoundMixer.computeSpectrum() в этом деле вообще не катит, он лишь отображает форму звуковой волны звучащую в данную секунду.
3. | Код |
import flash.display.Sprite; // we need a sprite to draw the waveform to
import flash.media.Sound; // we need the sound class to extract raw sound
// from our Sound objects
import flash.utils.ByteArray; // we need the byteArray class to store the sound
// data extracted from our objects
import com.adobe.images.JPGEncoder; // my, load encoder for save
// I have imported a random MP3 to my Flash Project and gave it class name "TestSound"
// So I just create a new Sound object using that "TestSound" MP3 that's in my library.
var sound:Sound = new Sound();
// We will store the raw sound data in a ByteArray called "soundData"
var soundData:ByteArray = new ByteArray();
// We need two sprites to draw the waveforms for the left and right channel
var waveformLeft:Sprite = new Sprite();
var waveformRight:Sprite = new Sprite();
// my color
var color = 0x333333;
// We set a basic line style and reset the drawing position for each Sprite
waveformLeft.graphics.moveTo(0,0);
waveformLeft.graphics.lineStyle(1,color);
waveformRight.graphics.moveTo(0,0);
waveformRight.graphics.lineStyle(1,color);
function loadComplete(event:Event):void{
// this is how we extract the raw sound data from our Sound object. The tricky
// part here is that the extract() method requires two parameters to be passed to it.
//
// - A reference to a ByteArray object in which the extracted raw sound data will be placed,
// which is the "soundData" byteArray we defined at line 12
//
// - A length parameter that specifies number of sample blocks to extract from that Sound
// object. Since we already know the data will be returned as 32-bit, 44100Hz Stereo, we
// can easily calculate the number of sound blocks by multiplying the sound length in
// seconds by the number of samples blocks per second (aka sample rate), which is 44100,
// but because the "length" property of the Sound object returns a value in milliseconds,
// we need to do a conversion here dividing it by 1000, so we can get a value in seconds,
// hence:
//
// Total Sample Blocks to Extract = (sound.length/1000)*44100;
sound.extract(soundData,Math.floor((sound.length/1000)*44100));
// the extract() method places the file pointer at the end of the ByteArray (something not
// mentioned in the Adobe Flash Documentation). Therefore, we need to reset the file pointer
// to the beginning of the ByteArray Object, which is position = 0
soundData.position = 0;
// for drawing purposes, we set our initial X Axis position to 0 and define a variable called
// "xStep", which determines how many pixels along the X Axis to move with each drawing step.
//
// As I have decided to draw lines connecting the minimum and maximum values of every 11025 sample
// blocks (or very 250ms) that means with a "xStep" value of 1 pixel, 250ms = 2 pixels, or
// 1 pixel = 125ms
var xPos:uint = 0;
var xStep = 1;
// since the raw sound data is a floating point number between -1 and 1, it will be really hard to
// notice the fluctuations if we use that number as-is to draw our waveform lines. Therefore we define
// an "yRation" variable to expand the visible range of the fluctuations that can be drawn on screen.
// I chose the number "100" based on error and trial - you can experiment with different numbers.
var yRatio:uint = stage.stageHeight/2;
var my = Math.ceil((sound.length/stage.stageWidth) * 87.8); // 87.8 - число найденное методом тыка
var my1 = Math.ceil((sound.length/1000)/60);
//trace(my + "-" + (sound.length/stage.stageWidth) );
// we loop through the soundData until we have enough bytes to read. We determine the number of
// bytes left using the "bytesAvailable" property of the "soundData" ByteArray object.
while(soundData.bytesAvailable > (44100*my1)){
var leftMin:Number = Number.MAX_VALUE; // a variable to store the minimum value for the Left Channel
var leftMax:Number = Number.MIN_VALUE; // a variable to store the maximum value for the Left Channel
var rightMin:Number = Number.MAX_VALUE;// a variable to store the minimum value for the Right Channel
var rightMax:Number = Number.MIN_VALUE; // a variable to store the maximum value for the Right Channel
for (var i:uint = 0;i<my;i++) // analyze every 11025 sample blocks and determine their
{ // minimum and maximum values
// we use the "readFloat()" method of the "soundData" ByteArray object to retrieve the raw sound
// data for the left and right channels. When you call "readFloat()" it retrieves the next 4 bytes
// from the ByteArray object, converts them to a 32-bit single precision floating point number and
// moves the file pointer to the next sequence of 4 bytes (not explained in the Adobe Flash Documentation)
var leftChannel:Number = soundData.readFloat(); // read raw sound data for left channel (4 bytes/32 bits)
var rightChannel:Number = soundData.readFloat();// read raw sound data for right channel (next 4 bytes/32 bits)
// 4 bytes + 4 bytes = 8 bytes = 1 sample block, remember? :)
// check if we have a new minumum or maximum values for the left or right channels
if (leftChannel < leftMin) leftMin = leftChannel;
if (leftChannel > leftMax) leftMax = leftChannel;
if (rightChannel < rightMin) rightMin = rightChannel;
if (rightChannel > rightMax) rightMax = rightChannel;
}
// draw lines connecting the minimum and maximum values of the left and right channels
// to their corresponding sprites.
waveformLeft.graphics.lineTo(xPos,leftMin*yRatio);
waveformRight.graphics.lineTo(xPos,rightMin*yRatio);
xPos += xStep;
waveformLeft.graphics.lineTo(xPos,leftMax*yRatio);
waveformRight.graphics.lineTo(xPos,rightMax*yRatio);
xPos += xStep;
}
// at this point the waveforms have been drawn to our left channel and right channel sprites.
// it's time to position these sprites relative to the Stage and add them to the Stage as well.
waveformLeft.x = 0;
waveformLeft.y = stage.stageHeight/2;
waveformRight.x = 0;
waveformRight.y = stage.stageHeight/2;
stage.addChild(waveformLeft);
stage.addChild(waveformRight);
// save in file
var raw:BitmapData = new BitmapData(stage.stageWidth, stage.stageHeight);
raw.draw(stage);
//кстати, чтоб этот энкодер заработал нужно было в туже папку где лежит и fla файл подкинуть библеотеку флешовскую https://github.com/mikechambers/as3corelib/
var jpgEncoder:JPGEncoder = new JPGEncoder(100);
var jpgStream:ByteArray = jpgEncoder.encode(raw);
//var fil:FileReference = new FileReference();
//fil.save(jpgStream, "image.jpg");
}
sound.addEventListener(Event.COMPLETE, loadComplete);
sound.load(new URLRequest("test6.mp3"));
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