srecord FrequencyImageFromURL(S url) {
  // all broken?!
  //S url = "https://gaz.ai/dl/audiostreams/gigsauntppvwjyrq.ogg";
  //S url = "https://gaz.ai/dl/audiostreams/zgmyptzpqlvafoyz.ogg";
  //S url = "https://gaz.ai/dl/audiostreams/jlokvemsxqhuaups.ogg";
  
  *() { url = "https://gaz.ai/dl/audiostreams/bjfxzzpdtuhxewdx.ogg"; }
  
  BWImage image;
  
  run {
    temp var opus = new DecodeOpusStream(url);
    opus.minBytesPreloaded = 65536*2;
    temp var samples = opus!;
    opus.machine.init();
    opus.machine.opusDecoder.printResets = true;
    var querySound = SampleIteratorToQuerySound(1, samples);
    
    new PianoSampler2 sampler;
    //sampler.debug = true;
    sampler.frequencies = intersperseHalfTones(sampler.frequencies);
    sampler.loadSound(querySound, 1);
    sampler.fixedFactor = 5e-4;
    
    var windowSeconds = .05;
    var windowSamples = windowSeconds*sampler.sampleRate;
    printVars(+windowSeconds, +windowSamples);
    
    var relativeWindowSpeed = .5;
    
    int peekSize = iceil(max(windowSamples, sampler.minWindowSizeForBase())*2);
    
    var totalSeconds = 5;
    var startAtSeconds = 0;
    
    var endAtSample = (startAtSeconds+totalSeconds)*sampler.sampleRate;
    
    var seconds = doubleRangeWithLength(startAtSeconds, windowSeconds);
    DoubleRange sampleRange = scaleDoubleRange(seconds, sampler.sampleRate);
    
    // make initial window
    print(+peekSize);
    sampler.makeWindowAround(sampleRange.start, peekSize);
    printVars(+seconds, +sampleRange, bounds := sampler.bounds());
    
    new L<MakesBufferedImage> images;
    
    int safety = 0;
    while ping (sampleRange.end <= endAtSample && safety++ <= 1000) {
      //print(+sampleRange);
      images.add(sampler.imageColumn(sampler.measureWindow(sampleRange)));
      sampleRange = shiftDoubleRange(sampleRange, windowSamples*relativeWindowSpeed);
    }
    
    image = mergeBWImagesHorizontally(map toBWImage(images), spacing := 0);
    print(nSamples := opus.samplesSeen());
    print(sampler.stats());
  }
 
  void showImage { 
    dm_showPixelatedImage(image);
  }
}