我想用Matlab中的应用程序设计器编写一个简单的音频过滤应用程序。一个人应该能够加载音频文件,按播放和改变参数,如输入增益,截止频率等,而文件正在播放。
我只是不知道如何能够实时更改参数并更新相应的变量,以便人们能够听到过滤器是如何更改的。
这是我现在写的代码:
classdef EulerFilter < matlab.apps.AppBase
% Properties that correspond to app components
properties (Access = public)
UIFigure matlab.ui.Figure
CutoffKnobLabel matlab.ui.control.Label
CutoffKnob matlab.ui.control.Knob
PlayButton matlab.ui.control.StateButton
end
properties (Access = public)
inputGain % input Gain
CutoffHz % cutoff frequency in Hz
end
methods (Access = public)
function play(app)
% setup file stream
frameLength = 256;
fileReader = dsp.AudioFileReader(...
'Sun Behind CloudsDry.wav',...
'SamplesPerFrame',frameLength);
deviceWriter = audioDeviceWriter(...
'SampleRate',fileReader.SampleRate);
% code snippet
% porcessing of frames
while ~isDone(fileReader)
% code snippet
end
release(fileReader);
release(deviceWriter);
end
end
methods (Access = private)
% Code that executes after component creation
function startupFcn(app)
app.inputGain = 1;
app.CutoffHz = 22000;
end
% Value changed function: PlayButton
function PlayButtonValueChanged(app, event)
value = app.PlayButton.Value;
play(app);
end
% Value changing function: CutoffKnob
function CutoffKnobValueChanging(app, event)
%display(event)
changingValue = event.Value;
app.CutoffHz = changingValue;
end
end
% App initialization and construction
methods (Access = private)
% Create UIFigure and components
function createComponents(app)
% Create UIFigure
app.UIFigure = uifigure;
app.UIFigure.Position = [100 100 640 480];
app.UIFigure.Name = 'UI Figure';
% Create CutoffKnobLabel
app.CutoffKnobLabel = uilabel(app.UIFigure);
app.CutoffKnobLabel.HorizontalAlignment = 'center';
app.CutoffKnobLabel.Position = [159 322 37 22];
app.CutoffKnobLabel.Text = 'Cutoff';
% Create CutoffKnob
app.CutoffKnob = uiknob(app.UIFigure, 'continuous');
app.CutoffKnob.Limits = [10 22000];
app.CutoffKnob.MajorTicks = [10 1000 5000 22000];
app.CutoffKnob.ValueChangingFcn = createCallbackFcn(app, @CutoffKnobValueChanging, true);
app.CutoffKnob.Position = [155 367 45 45];
app.CutoffKnob.Value = 22000;
% Create PlayButton
app.PlayButton = uibutton(app.UIFigure, 'state');
app.PlayButton.ValueChangedFcn = createCallbackFcn(app, @PlayButtonValueChanged, true);
app.PlayButton.Text = 'Play';
app.PlayButton.Position = [60 40 100 22];
end
end
methods (Access = public)
% Construct app
function app = EulerFilter
% Create and configure components
createComponents(app)
% Register the app with App Designer
registerApp(app, app.UIFigure)
% Execute the startup function
runStartupFcn(app, @startupFcn)
if nargout == 0
clear app
end
end
% Code that executes before app deletion
function delete(app)
% Delete UIFigure when app is deleted
delete(app.UIFigure)
end
end
end
它主要是Matlab为图形用户界面生成的函数。我添加了一些属性,其中包含输入增益、截止值等的值,以及执行信号处理的play()函数。
我可以运行应用程序,按下播放按钮,听到正在播放的音频文件,但当我改变截止频率,例如,没有改变。我想这是因为当按下play按钮时,我在回调函数中执行play()函数,因此在另一个按钮完成之前,不能执行切断旋钮时的回调函数。
当我第一次更改参数,然后按播放,一切都是正确的,除了我不能改变参数时,文件正在播放。
我尝试过以下方法,但没有成功:
在play()函数的while循环中调用回调函数,但我不知道需要传递哪个参数
事件
(Matlab总是告诉我它不知道缺少命令或参数)或者这是否有用
在runStartupFcn()中执行play()函数,但此函数在显示图形用户界面之前执行,这当然是无用的
据我所知,我不能在其他地方添加函数
所以现在的问题是:我能让应用程序实时工作吗?
我期待着你的回答!
 —— 流水线)
