C++ FMOD Studio 无法为 FMOD_DSP_PARAMETER_FFT 提供频率值。分析

Question

我试图在 3D 平面中表示声音的频谱，但我只能播放声音，无法将 dsp 放入 FMOD_DSP_PARAMETER_FFT 结构中，numchannels 和 length 始终 = 0

我的代码是这样的：

FMOD::System     *system;
FMOD::Sound      *sound1;
FMOD::Channel    *channel = 0;
FMOD::ChannelGroup *mastergroup;
FMOD::DSP         *mydsp, *dsphead, *dspchannelmixer;
FMOD::DSPConnection *conection;
FMOD_RESULT       result;
unsigned int      version;
result = FMOD::System_Create(&system);
result = system->getVersion(&version);

result = system->init(32, FMOD_INIT_NORMAL, NULL);


result = system->createSound("mysong.mp3",FMOD_DEFAULT, 0, &sound1);
result = sound1->setMode(FMOD_LOOP_NORMAL);
result = system->playSound(sound1, 0, true, &channel);

/*
Create the DSP effect.
*/

result = system->createDSPByType(FMOD_DSP_TYPE_FFT, &mydsp);
result = mydsp->setParameterFloat(FMOD_DSP_FFT_SPECTRUMDATA, 300.0f);

result = system->getMasterChannelGroup(&mastergroup);
result = mastergroup->getDSP(FMOD_CHANNELCONTROL_DSP_HEAD, &dsphead);
result = dsphead->getInput(0, &dspchannelmixer, 0);

result = dsphead->disconnectFrom(dspchannelmixer);
result = dsphead->addInput(mydsp, &conection);
result = mydsp->addInput(dspchannelmixer);

result = mydsp->setBypass(true);
result = mydsp->setActive(true);

char s[256];
unsigned int len;
float freq[32];

float fft = 0;
std::vector<float> fftheights;

//program loop
while (1) {


  unsigned int ms = 0;
  unsigned int lenms = 0;
  bool         playing = 0;
  bool         paused = 0;
  int          channelsplaying = 0;

  if (channel)
  {
    FMOD::Sound *currentsound = 0;
    result = channel->setPaused(false);
    result = channel->setMute(false);
    result = channel->isPlaying(&playing);
    result = channel->getPaused(&paused);
    result = channel->setVolume(0.5);
    result = channel->getPosition(&ms, FMOD_TIMEUNIT_MS);
    channel->getCurrentSound(&currentsound);
    if (currentsound)
    {
      result = currentsound->getLength(&lenms, FMOD_TIMEUNIT_MS);
    }
  }
  system->getChannelsPlaying(&channelsplaying);
  render_function();
  FMOD_DSP_PARAMETER_FFT *fftparameter;
  result = mydsp->getParameterData(FMOD_DSP_FFT_SPECTRUMDATA, (void **)&fftparameter, 0, 0, 0);
  result = mydsp->getOutput(FMOD_DSP_FFT_SPECTRUMDATA, &mydsp, 0);

  for (int channelfft = 0; channelfft < fftparameter->numchannels; channelfft++)
  {
    for (int bin = 0; bin < fftparameter->length; bin++)
    {
      float val = fftparameter->spectrum[channelfft][bin];
      if (channelfft == 0){
        fftheights.push_back(val);
      }
      else{
        fftheights[bin] += val;
      }

    }
  }
    result = system->update();
}

由于此错误，我无法将值推回 fftheights 向量并且始终为空 0，如果您能帮助我，我会同意。

谢谢。

Answer 1

我认为您需要使用以下方法设置这些值：

    mydsp->setParameterInt( ... ); // <-- put stuff there

另外，通过查看“结果”来检查函数是否返回任何错误

查看Here 了解更多信息。