Only one channel is playing at time when adding DSP in group

FMOD Engine
1

When I add a plugin to group, setting a read callback in FMOD_DSP_DESCRIPTION make the channels not playing simultaneously. Per example, If I play the sound1 and sound2 just after, both sounds play together, but adding the DSP with read callback, when I play sound1 and after sound2, the sound1 stops.

Any help?

2

What version of FMOD are you using?
Are you seeing any errors or warnings in the console?

3

The problem is that I’ve recorded sound input buffer in disk but don’t passed it ahead through outputbuffer. My final working code for the read callback follows:

auto recordCallback = [](
        FMOD_DSP_STATE* dspState,
        float* inBuffer,
        float* outBuffer,
        unsigned int length,
        int inChannelCount,
        int* outChannelCount
) -> FMOD_RESULT F_CALLBACK {
    void* ptr;
    dspState->functions->getuserdata(dspState, &ptr);
    auto* r = reinterpret_cast<Recorder*>(ptr);

    r->enqueue(inBuffer, length * inChannelCount);

    for (auto sample = 0U; sample < length; sample++) {
        for (auto channel = 0; channel < inChannelCount; channel++) {
            auto index = (sample * inChannelCount) + channel;
            outBuffer[index] = r->recordSilenced() ? 0 : inBuffer[index];
        }
    }

    return FMOD_OK;
};
4

Yes, that’s makes sense, when writing a capture DSP it is important to pass the input buffer data through to the output buffer, otherwise the signal will go silent.