How to save 3D sound effects to wav files?


I designed a 3D sound effect, but the audio I saved is different from the one I previewed. How should I save the 3D sound effect?Here is the code I initialized to save:

void FMODCore::saveInit3D(char *inputPath, char *outPath) {
result = system->setOutput(FMOD_OUTPUTTYPE_WAVWRITER_NRT);
result = system->setSoftwareFormat(24000, FMOD_SPEAKERMODE_DEFAULT, 10);
result = system->init(32, FMOD_INIT_NORMAL, (void *) outPath);
result = system->set3DSettings(1.0, DISTANCEFACTOR, 1.0f);
result = system->createSound(inputPath, FMOD_3D, 0, &sound);
result = sound->set3DMinMaxDistance(0.5f * DISTANCEFACTOR, 5000.0f * DISTANCEFACTOR);


How is the sound different?


The listener’s speed, position, and direction of movement are different from what I set.
I solved this problem by using real-time save, but it was time-consuming.
Can 3D effects be saved using NRT?


Nothing in the system knows what the output is or behaves differently because of it.

How are you measuring the difference?

This post may help with understanding FMOD_OUTPUTTYPE_WAVEWRITER_NRT a bit more:

The way FMOD_OUTPUTTYPE_WAVEWRITER_NRT works is it generates audio every time System::update is called. The amount of data generated per ‘update’ is governed by the bufferlength parameter of System::setDSPBufferSize.

So the faster you call System::update the faster the data is generated. Now the important part for your job is to convert ‘x’ number of calls to System::update into something you can match to your timeline.

By default FMOD operates at a sample rate of 48000 samples per second (configurable via System::setSoftwareFormat). So if you set ‘bufferlength’ to 1024, each time you call System::update 1024 samples will be generated (written to the wav file). So… 1024 / 48000 = 0.021333 seconds ~ 21.3 milliseconds of data is generated per call.