我的问题是下面这个问题的后续问题，但我认为最好开始一个新问题。
所以我在 Flash 中有一个波形绘图实现，它从 mp3 中提取 pcm 数据并在多个缩放级别绘制波形。它工作正常，直到您开始处理超过几分钟的曲目，然后它太慢了，令人无法接受。所以我追求更快的解决方案。
我首先想到尝试使用像素弯曲器，因为我听说它的计算速度非常快。这是真的，但正如上面发布的链接所示，缺少 for 循环使该技术不适合。
所以现在我在想什么是最好的途径太钱包作为替代品。
用 c 编写我的波形计算代码并使用炼金术会给我带来可感知的速度和性能改进吗？它本质上仍然只是 as3 运行对吗？
使用某种服务器端脚本会更好吗？也许将 pcm 数据作为字节数组传递给 php 脚本并让脚本返回绘图数据？
你能想到我可以尝试研究的任何其他技术吗？
编辑：>>
我在 as3 中尝试做的是
将 mp3s 音频数据提取到字节数组 确定以最大缩放级别绘制的虚拟像素数（例如，800 像素 = 2 倍缩放时轨道的 10 秒）
因此，如果我的样本数 = 33315840 并且最大虚拟像素数 = 1600（需要滚动，因为我的视口是 800 像素宽），那么我的块大小 = 33315840/1600 =20822
因此，对于 hte bytearray 中的每 20822 个样本，我找到最大值并将该值用作我的绘图值
编辑 2
@backtodos
我考虑过你提出的观点，它似乎比整个最大业务更明智。
我已经完成了以下代码，我认为它代表了您所说的内容。一个问题是，如果我将分辨率更改为大于 800 的任何值，我会得到非常高的线条和非常短的线条，这看起来很奇怪。在 800 处，它的波形非常好！
如果我的分辨率超过 1600，当我尝试绘制矩形时会抛出错误，说明参数无效。
我想我对你的缩放策略有点困惑。你说“如果你放大，你用重复的分辨率重新绘制波形”。我真的不明白你的意思是什么？我知道我一次只能绘制 800 个像素。假设我进行了 2 倍缩放，这是否意味着我将样本源的读取量增加一倍并拥有 1600 个绘图点，但根据滚动位置一次只能绘制 800 个？
private function calculatePlottingData():void
{
this._container=new UIComponent()
drawon=new MovieClip()
_container.addChild(drawon)
addChild(_container)
var spriteSize:Number;
spriteSize=800; // my resolution
//ba is a bytearray filled with my extracted audio data
//blocksize helps me determine where in the bytearray
//to read a sample value from for plotting
blocksize=Math.floor(ba.length / spriteSize);
var tstart:Number=getTimer()
var l:Number
var r:Number
var la:Number
var ra:Number
var readpoint:int=0;
var val:Number;
for (var i:int=0; i < spriteSize; i++)
{
readpoint=i * blocksize
ba.position=readpoint;
//read teh left and right sample
la=ba.readFloat();
ra=ba.readFloat();
val=(la + ra) / 2;
plottingvalues[i]=val
drawon.graphics.beginFill(0xff0000)
}
var tend:Number=getTimer() - tstart;
trace("time taken=" + tend / 1000)
draw()
}
private function draw():void
{
var val:Number
for (var i:int=0; i < _viewportwidth; i++)
{
drawon.graphics.beginFill(0xffffff)
val=plottingvalues[i];
drawon.graphics.drawRect(i, 50, 1, val * 50)
}
}
编辑 3 >基于只获得 800 个绘图点的改进代码，此代码对于我的目的来说看起来足够快。使用@backtodos 坚持解决方案的建议可以节省大量处理时间。
package drawing
{
import flash.display.Bitmap;
import flash.display.BitmapData;
import flash.display.MovieClip;
import flash.events.MouseEvent;
import flash.geom.Rectangle;
import flash.media.Sound;
import flash.utils.ByteArray;
import flash.utils.getTimer;
import mx.core.Application;
public class WaveformView extends MovieClip
{
private var _sound:Sound
private var _resolution:Number
private var _quality:int=1;
private var _buffersize:int;
private var _ba:ByteArray=new ByteArray()
private var _step:Number
private var _zoomby:int=1;
private var _zoomfactor:int=2;
private var _blocksize:int;
private var _scrollbar:Bitmap
private var _scrollthumb:MovieClip
private var _relativeThumbPosition:Number=0
private var _sliderRange:int
private var _sliderCenterMinLeft:int
private var _sliderCenterMax_Right:int;
public var _slider_rel_pos:Number=0;
private var _sliderCenter:Number=0;
public function WaveformView(snd:Sound, res:Number=800, quality:int=2, buffersize:int=2048)
{
super();
this._sound=snd;
this._resolution=res;
this._quality=quality; // not implemented yet
this._buffersize=buffersize;
initScrollBar();
getPCM()
drawwaveform()
}
private function initScrollBar():void
{
var sbbmd:BitmapData=new BitmapData(_resolution, 20, false, 0xcccccc)
_scrollbar=new Bitmap(sbbmd)
_scrollbar.y=120
addChild(_scrollbar)
sbbmd=new BitmapData(_resolution, 16, false, 0xeeeeee)
_scrollthumb=new MovieClip()
_scrollthumb.graphics.beginFill(0xff0000)
_scrollthumb.graphics.drawRect(0, 0, _resolution, 10)
_scrollthumb.graphics.endFill()
_scrollthumb.y=125
addChild(_scrollthumb)
_scrollthumb.buttonMode=true
_scrollthumb.addEventListener(MouseEvent.MOUSE_DOWN, beginthumbdrag)
}
private function beginthumbdrag(e:MouseEvent):void
{
_scrollthumb.startDrag(false, new Rectangle(_scrollbar.x, _scrollbar.y + 5, _scrollbar.width - (_scrollthumb.width), 0))
_scrollthumb.addEventListener(MouseEvent.MOUSE_MOVE, shuttleMoving, false, 0, true);
_scrollthumb.addEventListener(MouseEvent.MOUSE_UP, endthumbdrag, false, 0, true);
}
private function endthumbdrag(e:MouseEvent):void
{
_scrollthumb.stopDrag();
e.updateAfterEvent();
_scrollthumb.removeEventListener(MouseEvent.MOUSE_MOVE, shuttleMoving);
}
private function shuttleMoving(e:MouseEvent):void
{
calculateShuttleRelativePosition();
drawwaveform()
e.updateAfterEvent()
}
private function calculateShuttleRelativePosition():void
{
var _x:Number=_scrollthumb.x
_sliderCenter=_x + (_scrollthumb.width / 2)
_sliderRange=_scrollbar.width - _scrollthumb.width;
_slider_rel_pos=(_sliderCenter - _sliderCenterMinLeft) / _sliderRange
}
public function getPCM():void
{
var len:int=_sound.length * 44.1
_sound.extract(_ba, len)
this._blocksize=_ba.length / (_resolution * _zoomby)
shaveblocksize()
}
public function zoomin():void
{
if (this._zoomby < 16)
{
this._zoomby*=2
resizeThumb()
drawwaveform()
}
}
public function zoomout():void
{
if (_zoomby >= 2)
{
this._zoomby/=2
resizeThumb()
drawwaveform()
}
}
private function resizeThumb():void
{
_scrollthumb.width=_scrollbar.width / _zoomby
if (_scrollthumb.width == _resolution)
{
_slider_rel_pos=0
}
_sliderCenterMinLeft=_scrollthumb.width / 2;
_sliderCenterMax_Right=_scrollbar.width - (_scrollthumb.width / 2);
_sliderRange=_scrollbar.width - _scrollthumb.width;
_sliderRange=_scrollbar.width - _scrollthumb.width;
_scrollthumb.x=(_slider_rel_pos * _sliderRange)
}
public function drawwaveform():void
{
var starttime:Number=getTimer()
var readposition:int
var l:Number
var r:Number
var p:Number
this._blocksize=_ba.length / (_resolution * _zoomby)
shaveblocksize()
this.graphics.clear()
this.graphics.beginFill(0xc5c5c5, 0.5)
this.graphics.drawRect(0, 50, _resolution, 1)
var max:int=_ba.length - (_blocksize * _resolution)
var pos:int=Formulas.interpolate(_slider_rel_pos, 0, max)
_ba.position=pos
for (var i:int=0; i < _resolution; i++)
{
l=Math.abs(_ba.readFloat());
r=Math.abs(_ba.readFloat());
l*=50
r*=50
p=(l + r)/2
try
{
this.graphics.drawRect(i, 50, 1, p)
this.graphics.drawRect(i, 50, 1, -p)
}
catch (e:Error)
{
}
_ba.position+=_blocksize
}
}
private function shaveblocksize():void
{
do
{
_blocksize--
} while (_blocksize % 4);
}
}
}
解决方案 感谢 backtodos 的帮助。这可能需要大量的优化，但对某些人来说这是一个很好的起点。
package drawing
{
import flash.display.Bitmap;
import flash.display.BitmapData;
import flash.display.MovieClip;
import flash.events.MouseEvent;
import flash.geom.Rectangle;
import flash.media.Sound;
import flash.utils.ByteArray;
import flash.utils.getTimer;
public class WaveformView extends MovieClip
{
private var _sound:Sound
private var _resolution:Number
private var _quality:int=1;
private var _buffersize:int;
private var _ba:ByteArray=new ByteArray()
private var _zoomby:int=1;
private var _zoomXFactor:int=2;
private var _maximumSecondsPerViewPort:int=10;
;
private var _blocksize:int;
private var _scrollbar:Bitmap
private var _scrollthumb:MovieClip
private var _relativeThumbPosition:Number=0
private var _sliderRange:int
private var _sliderCenterMinLeft:int
private var _sliderCenterMax_Right:int;
public var _slider_rel_pos:Number=0;
private var _sliderCenter:Number=0;
private var _resolutions:Array
private var _zoomsInSecondsArray:Array=new Array();
private var _numberOfZoomLevels:int;
public function WaveformView(snd:Sound, res:Number=800, quality:int=2, buffersize:int=2048, height:int=100)
{
super();
this._sound=snd;
this._resolution=res;
this._quality=quality; // not implemented yet
this._buffersize=buffersize;
// addChild(viewportBitmap)
_resolutions=new Array()
initScrollBar();
getPCM()
calculateZoomLevelData()
drawwaveform()
}
public function calculateZoomLevelData():void
{
_zoomsInSecondsArray=[]
var amt:int=Math.round(_sound.length / 1000);
_zoomsInSecondsArray.push(amt);
while (amt >= _maximumSecondsPerViewPort)
{
amt=amt / _zoomXFactor;
if (amt >= _maximumSecondsPerViewPort)
{
_zoomsInSecondsArray.push(amt);
}
}
_numberOfZoomLevels=_zoomsInSecondsArray.length;
var checkSize:int=_resolution;
var r:ResolutionCache
r=new ResolutionCache(checkSize)
_resolutions.push(r)
for (var c:int=1; c < _numberOfZoomLevels + 1; c++)
{
checkSize=checkSize * _zoomXFactor;
r=new ResolutionCache(checkSize)
_resolutions.push(r)
}
_resolutions.pop()
}
private function initScrollBar():void
{
var sbbmd:BitmapData=new BitmapData(_resolution, 20, false, 0xcccccc)
_scrollbar=new Bitmap(sbbmd)
_scrollbar.y=120
addChild(_scrollbar)
sbbmd=new BitmapData(_resolution, 16, false, 0xeeeeee)
_scrollthumb=new MovieClip()
_scrollthumb.graphics.beginFill(0xff0000)
_scrollthumb.graphics.drawRect(0, 0, _resolution, 10)
_scrollthumb.graphics.endFill()
_scrollthumb.y=125
addChild(_scrollthumb)
_scrollthumb.buttonMode=true
_scrollthumb.addEventListener(MouseEvent.MOUSE_DOWN, beginthumbdrag)
}
private function beginthumbdrag(e:MouseEvent):void
{
_scrollthumb.startDrag(false, new Rectangle(_scrollbar.x, _scrollbar.y + 5, _scrollbar.width - (_scrollthumb.width), 0))
_scrollthumb.addEventListener(MouseEvent.MOUSE_MOVE, shuttleMoving, false, 0, true);
_scrollthumb.addEventListener(MouseEvent.MOUSE_UP, endthumbdrag, false, 0, true);
}
private function endthumbdrag(e:MouseEvent):void
{
_scrollthumb.stopDrag();
e.updateAfterEvent();
_scrollthumb.removeEventListener(MouseEvent.MOUSE_MOVE, shuttleMoving);
}
private function shuttleMoving(e:MouseEvent):void
{
calculateShuttleRelativePosition();
drawwaveform()
//e.updateAfterEvent()
}
private function calculateShuttleRelativePosition():void
{
var _x:Number=_scrollthumb.x
_sliderCenter=_x + (_scrollthumb.width / 2)
_sliderRange=_scrollbar.width - _scrollthumb.width;
_slider_rel_pos=(_sliderCenter - _sliderCenterMinLeft) / _sliderRange
}
public function getPCM():void
{
var len:int=_sound.length * 44.1
_sound.extract(_ba, len)
this._blocksize=_ba.length / (_resolution * _zoomby)
shaveblocksize()
}
public function zoomin():void
{
if (this._zoomby < 16)
{
this._zoomby*=2
resizeThumb()
drawwaveform()
}
}
public function zoomout():void
{
if (_zoomby >= 2)
{
this._zoomby/=2
resizeThumb()
drawwaveform()
}
}
private function resizeThumb():void
{
_scrollthumb.width=_scrollbar.width / _zoomby
if (_scrollthumb.width == _resolution)
{
_slider_rel_pos=0
}
_sliderCenterMinLeft=_scrollthumb.width / 2;
_sliderCenterMax_Right=_scrollbar.width - (_scrollthumb.width / 2);
_sliderRange=_scrollbar.width - _scrollthumb.width;
_sliderRange=_scrollbar.width - _scrollthumb.width;
_scrollthumb.x=(_slider_rel_pos * _sliderRange)
}
private function getResolutionCache(vww:int):ResolutionCache
{
var r:ResolutionCache
for (var i:int=0; i < _resolutions.length; ++i)
{
if (_resolutions[i].name == vww)
{
r=_resolutions[i];
break;
}
}
return r;
}
public function drawwaveform():void
{
var starttime:Number=getTimer()
var readposition:int
var viewPortWidth:int=_resolution;
var virtualWindowWidth:int=_resolution * _zoomby;
var l:Number
var r:Number
var p:Number
var rc:ResolutionCache=getResolutionCache(virtualWindowWidth)
this._blocksize=_ba.length / virtualWindowWidth
shaveblocksize()
this.graphics.clear()
this.graphics.beginFill(0xc5c5c5, 0.5)
this.graphics.drawRect(0, 50, _resolution, 1)
var pixel:int=(_slider_rel_pos * (virtualWindowWidth - viewPortWidth - 1));
var readpoint:int=pixel * _blocksize;
var rect:Rectangle
_ba.position=readpoint;
this.graphics.clear()
this.graphics.beginFill(0xffffff)
for (var i:int=0; i < _resolution; i++)
{
if (rc.points[pixel] == -1)
{
_ba.position=pixel * _blocksize
l=_ba.readFloat() * 100;
r=_ba.readFloat() * 100;
p=(l + r) / 2
rc.addPoint(pixel, i, height / 2, p)
rect=rc.points[pixel]
//this.graphics.drawRect(rect.x,rect.y,rect.width,rect.height)
this.graphics.drawRect(i, 50, 1, p)
this.graphics.drawRect(i, 50, 1, -p)
}
else
{
//viewportBitmapdata.fillRect(rc.points[pixel], 0xffffff)
rect=rc.points[pixel]
this.graphics.drawRect(i, 50, 1, rect.height)
this.graphics.drawRect(i, 50, 1, -rect.height)
//this.graphics.drawRect(i,height/2,rect.width,rect.height)
}
pixel++
}
}
private function shaveblocksize():void
{
do
{
_blocksize--
} while (_blocksize % 4);
}
}
}