Playing sound specific range

FMOD Engine
9

Sample accurate playback is achieved with ChannelControl::setPosition to set the start time and ChannelControl::setDelay to set a duration. The duration of ChannelControl::setDelay needs to be offset by the current dsp clock time, which you can get through ChannelControl::getDSPClock.

void SetChannelRange(FMOD::ChannelGroup *channel, int start, int end)
{
    int duration = stop - start;
    int sampleRate;
    unsigned long long time;
    
    result = system->getSoftwareFormat(&sampleRate, 0, 0);
    ERRCHECK(result);
    result = channel->getDSPClock(0, &time);
    ERRCHECK(result);

    result = channel->setPosition(start * sampleRate, FMOD_TIMEUNIT_PCM);
    ERRCHECK(result);
    result = channel->setDelay(0, time + duration * sampleRate);
    ERRCHECK(result);
}

As for the callback, I can see you are using C#, does your callback signature look like this?

[AOT.MonoPInvokeCallback(typeof(FMOD.CHANNELCONTROL_CALLBACK))]
static FMOD.RESULT ChannelControlCallbackFunc(
  IntPtr channelcontrol,
  FMOD.CHANNELCONTROL_TYPE controltype,
  FMOD.CHANNELCONTROL_CALLBACK_TYPE callbacktype,
  IntPtr commanddata1,
  IntPtr commanddata2
){}