[SOLVED] IXAudio2Engine::CreateSourceVoice fails

IXAudio2Engine::CreateSourceVoice fails

I receive the Error XAUDIO2_E_INVALID_CALL when I try to call IXAudio2Engine::CreateSourceVoice. My code for creating a source voice is as follows:

auto sample_rate = quality_to_sample_rate(settings.quality, sound_category::effect);
WAVEFORMATEX wave_format{ // 8000Hz 16 bit mono WAV
    .wFormatTag = WAVE_FORMAT_PCM,
    .nChannels = 1,
    .nSamplesPerSec = sample_rate,
    .nAvgBytesPerSec = sample_rate* 2,
    .wBitsPerSample = 16,
    .cbSize = 0,
};
XAUDIO2_SEND_DESCRIPTOR send_descriptor{.Flags = 0, .pOutputVoice = master_voice};
XAUDIO2_VOICE_SENDS sends{.SendCount = 1, .pSends = &send_descriptor};
res = sound_engine->CreateSourceVoice(&v, &wave_format, 0, 2.0f, nullptr, &sends);
if(FAILED(res)) {
    log_error("Could not create effect source voice with", sample_rate, "Hz");
    throw std::runtime_error("Could not create effect source voice");
}
log_debug("Created effect source voice with ", sample_rate, "Hz at ", (void*)v);

master_voice is not nullptr and is of type IXAudio2MasteringVoice* (i.e. CreateMasteringVoice returned S_OK!)

What am I missing?

Edit:

According to XAudio2 and *.wav loading, HRESULT 0x88960001 ,
it is possible to set pSendList to NULL which would result in using the MasteringVoice. but that does not help either.

Solution

Reading the docs helps:

nBlockAlign and nAvgBytesPerSecond need to be set correctly.
nBlockAlign needs to be (nChannels * (nBitsPerSample/8)) / 8 and
nAvgBytesPerSecond is nBlockAlign * nSamplesPerSecond