我可以在 Matlab 中将许多图形保存为批处理位图吗？

Question

我希望在 matlab 中分析 .wav 格式的长音频文件，并将整个音频长度导出为 2048x2048 像素位图中的频谱图。对于一秒钟的声音，我希望自动处理大约 20 个位图，并且我想让 matlab 在几个小时内处理 return 1000 个长音频位图，然后在另一个程序中进行进一步处理。

初学者可以吗？

Answer 1

您应该使用命令 print:

fig = figure();
%Plot some data
print (fig, '-noui', '-dbmp', 'myfile.bmp');

我建议您尝试使用 PNG (png) 而不是 BMP，因为您可以节省一些内存（或使用 256 个值 bmp bmp256）

Answer 2

这是一个旧的 SciLab 实现，可以帮助您入门。我建议将生成的频谱图保存为数据，而不是图像。并编写另一个可以将数据转换为图像的函数。

// For simple plotting, Positions in Milliseconds!!
function plotASpectrogram( source, startPosition, endPosition )

  [audio,sampleRate] = wavread(source);  

  startPosition = msecToSamples(startPosition, sampleRate);
  endPosition   = msecToSamples(endPosition, sampleRate);

  audio = cropAudio(audio, startPosition, endPosition );

  mapsound(audio);//,.1,100,2000,1,sampleRate);

  //Label axes   
  startPosition = samplesToMsec(startPosition, sampleRate);  

  if(startPosition==0)
    startPosition = "";
  else
    startPosition = " + " + string(startPosition/1000);
  end      

  labelTheAxes("", "", "Spec " + string(getNameFromSource(source)));  
endfunction

// Create a linear spectrogram
// parameter [in] audio - audio file read in with wavread
// parameter [in] specFreqSamples - number of frequencies
// parameter [in] specTimeSamples - number of time samples
// parameter [in] specOverlap - amount of overlap in spectrogram windows
// parameter [in] hann - precalculated hanning window for smoothing
// parameter [out] tempSpec - A matrix containing the spectrogram
function tempSpec = createLinearSpectrogram( audio, specFreqSamples, specTimeSamples, specOverlap, hann )

  //Allocate memory for the input and output arrays. 
  tempSpec = zeros(St,specFreqSamples);
  in       = zeros(specTimeSamples);    //The input will have real values,
  out      = zeros(specFreqSamples,2);  //While the output will have complex values.It is also 1/2 the length of the input array +1.

  for i = 1:St
    //Store the input data into the input array
    for j = 1:specTimeSamples
      in(j) = audio(1,(i-1) * specTimeSamples/specOverlap + j);
      in(j) = in(j) * hann(j);
    end

    //Execute the FFT
    out(1:specTimeSamples,1) = real(fftw(in(1:specTimeSamples),1));
    out(1:specTimeSamples,2) = imag(fftw(in(1:specTimeSamples),1));

    //Convert the output into complex data and calculate the absolute value of every
    //output. Store it into the spectrogram array.
    for j = 1:specFreqSamples
      tempSpec(i,j) = sqrt(out(j,1) * out(j,1) + out(j,2) * out(j,2));
    end     
  end
endfunction

// Some utility functions
function labelTheAxes(Title, LabelX, LabelY)

  a=get("current_axes");
  a.x_label;
  a.y_label;
  xtitle(string(Title),string(LabelX), string(LabelY)); 

endfunction

function numberOfSamples = msecToSamples( numberOfMilliSeconds, sampleRate)
  numberOfSamples   = round((numberOfMilliSeconds / 1000) * sampleRate);
endfunction

function croppedAudio = cropAudio(audio, startPosition, endPosition)
  //Parameters in Samples!!!
  croppedAudio = audio(1,startPosition:endPosition);
endfunction

我可以在 Matlab 中将许多图形保存为批处理位图吗？

Can i save many graphs in Matlab as bitmaps with batch processing?

matlab

scilab