Channel Frequency of 0 not Respected for Streams

FMOD Engine
1

Hi!

I continuously manipulate the frequency of a channel through game interaction but for some odd reason when I get close to and eventually precisely to 0 the actual frequency stays at 100.

I confirmed that I literally call setFrequency with a float value of 0 but if I query the value afterwards using getFrequency I get back 100.

I noticed that the problem only happens when I load the corresponding music via FMOD_CREATESTREAM. If I load it via FMOD_CREATESAMPLE the problem is not there.

The documentation says:

Sounds opened as FMOD_CREATESAMPLE (not FMOD_CREATESTREAM or FMOD_CREATECOMPRESSEDSAMPLE) can be played backwards by giving a negative frequency.

But 0 should work in both cases, shouldn’t it?

I use the latest FMOD 2.02 lib at 2.02.25.

Best regards,
Thomas

2

Hi,

Thank you for the information.

Unfortunately, I was not able to reproduce the issue.

Would it be possible to get a code snippet to test on my side?

3

I was able to reproduce the issue with the following minimal example. I use an OGG file as music input and compiled on macOS. If you want, I can upload a full compilable example to my profile.

#include <chrono>
#include <fmod/fmod.hpp>
#include <iostream>
#include <thread>

namespace {
constexpr int k_maxAudioChannels = 32;
constexpr float k_rateStep = 0.01F;
constexpr const char* k_path = "assets/music.ogg";
constexpr int k_sleepTimeMs = 20;
}  // namespace

int main(int argc, char** args) {
  // Startup
  FMOD::System* system_p = nullptr;
  FMOD::System_Create(&system_p);
  system_p->init(k_maxAudioChannels, FMOD_INIT_NORMAL, nullptr);

  FMOD::ChannelGroup* musicChannelGroup_p = nullptr;
  system_p->createChannelGroup("Music Channel Group", &musicChannelGroup_p);

  // Load music
  FMOD::Sound* sound_p = nullptr;
  system_p->createSound(k_path, FMOD_CREATESTREAM, nullptr, &sound_p);

  // Read default frequency
  float defaultFreq = 0.F;
  sound_p->getDefaults(&defaultFreq, nullptr);

  // Play music
  FMOD::Channel* channel_p = nullptr;
  system_p->playSound(sound_p, musicChannelGroup_p, false, &channel_p);

  // Main loop
  float playbackRate = 1.F;
  while (true) {
    float freq = 0.F;
    channel_p->getFrequency(&freq);
    std::cout << "Channel frequency: " << freq << std::endl;

    channel_p->setFrequency(defaultFreq * playbackRate);
    system_p->update();

    playbackRate = std::max(playbackRate - k_rateStep, 0.F);
    std::this_thread::sleep_for(std::chrono::milliseconds(k_sleepTimeMs));
  }

  // Shutdown
  musicChannelGroup_p->stop();

  if (sound_p) {
    sound_p->release();
    sound_p = nullptr;
  }

  if (musicChannelGroup_p) {
    musicChannelGroup_p->release();
    musicChannelGroup_p = nullptr;
  }

  if (system_p) {
    system_p->close();
    system_p->release();
    system_p = nullptr;
  }

  return 0;
}

This example leads to the following output:

Channel frequency: 44100
Channel frequency: 44100
Channel frequency: 43659
Channel frequency: 43218
Channel frequency: 42777
Channel frequency: 42336
Channel frequency: 41895
Channel frequency: 41454
Channel frequency: 41013
Channel frequency: 40572
Channel frequency: 40131
Channel frequency: 39690
Channel frequency: 39249
Channel frequency: 38808
Channel frequency: 38367
Channel frequency: 37926
Channel frequency: 37485
Channel frequency: 37044
Channel frequency: 36603
Channel frequency: 36162
Channel frequency: 35721
Channel frequency: 35280
Channel frequency: 34839
Channel frequency: 34398
Channel frequency: 33957
Channel frequency: 33516
Channel frequency: 33075
Channel frequency: 32634
Channel frequency: 32193
Channel frequency: 31752
Channel frequency: 31311
Channel frequency: 30870
Channel frequency: 30429
Channel frequency: 29988
Channel frequency: 29547
Channel frequency: 29106
Channel frequency: 28665
Channel frequency: 28224
Channel frequency: 27783
Channel frequency: 27342
Channel frequency: 26901
Channel frequency: 26460
Channel frequency: 26019
Channel frequency: 25578
Channel frequency: 25137
Channel frequency: 24696
Channel frequency: 24255
Channel frequency: 23814
Channel frequency: 23373
Channel frequency: 22932
Channel frequency: 22491
Channel frequency: 22050
Channel frequency: 21609
Channel frequency: 21168
Channel frequency: 20727
Channel frequency: 20286
Channel frequency: 19845
Channel frequency: 19404
Channel frequency: 18963
Channel frequency: 18522
Channel frequency: 18081
Channel frequency: 17640
Channel frequency: 17199
Channel frequency: 16758
Channel frequency: 16317
Channel frequency: 15876
Channel frequency: 15435
Channel frequency: 14994
Channel frequency: 14553
Channel frequency: 14112
Channel frequency: 13671
Channel frequency: 13230
Channel frequency: 12789
Channel frequency: 12348
Channel frequency: 11907
Channel frequency: 11466
Channel frequency: 11025
Channel frequency: 10584
Channel frequency: 10143
Channel frequency: 9702.03
Channel frequency: 9261.03
Channel frequency: 8820.03
Channel frequency: 8379.03
Channel frequency: 7938.03
Channel frequency: 7497.03
Channel frequency: 7056.03
Channel frequency: 6615.03
Channel frequency: 6174.03
Channel frequency: 5733.03
Channel frequency: 5292.03
Channel frequency: 4851.03
Channel frequency: 4410.03
Channel frequency: 3969.03
Channel frequency: 3528.03
Channel frequency: 3087.03
Channel frequency: 2646.03
Channel frequency: 2205.03
Channel frequency: 1764.03
Channel frequency: 1323.03
Channel frequency: 882.03
Channel frequency: 441.03
Channel frequency: 100
Channel frequency: 100
Channel frequency: 100
Channel frequency: 100
Channel frequency: 100
...

Thanks!

Thomas