WASAPI Play .wav File.cpp

// Simple example code to load a Wav file and play it with WASAPI
// This is NOT complete Wav loading code. It is a barebones example 
// that makes a lot of assumptions, see the assert() calls for details
//
// References: 
// http://www-mmsp.ece.mcgill.ca/Documents/AudioFormats/WAVE/WAVE.html
// Handmade Hero Day 138: Loading WAV Files

#include <windows.h>
#include <mmdeviceapi.h>
#include <audioclient.h>

#include <assert.h>
#include <stdint.h>

// Struct to get data from loaded WAV file.
// NB: This will only work for WAV files containing PCM (non-compressed) data
// otherwise the layout will be different.
#pragma warning(disable : 4200)
struct WavFile {
    // RIFF Chunk
    uint32_t riffId;
    uint32_t riffChunkSize;
    uint32_t waveId;

    // fmt Chunk
    uint32_t fmtId;
    uint32_t fmtChunkSize;
    uint16_t formatCode;
    uint16_t numChannels;
    uint32_t sampleRate;
    uint32_t byteRate;
    uint16_t blockAlign;
    uint16_t bitsPerSample;
    // These are not present for PCM Wav Files
    // uint16_t cbSize;
    // uint16_t wValidBitsPerSample;
    // uint32_t dwChannelMask;
    // char subFormatGUID[16];

    // data Chunk
    uint32_t dataId;
    uint32_t dataChunkSize;
    uint16_t samples[]; // actual samples start here
};
#pragma warning(default : 4200)

bool win32LoadEntireFile(const char* filename, void** data, uint32_t* numBytesRead)
{    
    HANDLE file = CreateFileA(filename, GENERIC_READ, 0, 0, OPEN_EXISTING, 0, 0);  
    if((file == INVALID_HANDLE_VALUE)) return false;
    
    DWORD fileSize = GetFileSize(file, 0);
    if(!fileSize) return false;
    
    *data = HeapAlloc(GetProcessHeap(), 0, fileSize+1);
    if(!*data) return false;

    if(!ReadFile(file, *data, fileSize, (LPDWORD)numBytesRead, 0))
        return false;
    
    CloseHandle(file);
    ((uint8_t*)*data)[fileSize] = 0;
    
    return true;
}

void Win32FreeFileData(void *data)
{
    HeapFree(GetProcessHeap(), 0, data);
}

int main()
{
    void* fileBytes;
    uint32_t fileSize;
    bool result = win32LoadEntireFile("filename.wav", &fileBytes, &fileSize);
    assert(result);

    WavFile* wav = (WavFile*)fileBytes;
    // Check the Chunk IDs to make sure we loaded the file correctly
    assert(wav->riffId == 1179011410);
    assert(wav->waveId == 1163280727);
    assert(wav->fmtId == 544501094);
    assert(wav->dataId == 1635017060);
    // Check data is in format we expect
    assert(wav->formatCode == 1); // Only support PCM data
    assert(wav->numChannels == 2); // Only support 2-channel data
    assert(wav->fmtChunkSize == 16); // This should be true for PCM data
    assert(wav->sampleRate == 44100); // Only support 44100Hz data
    assert(wav->bitsPerSample == 16); // Only support 16-bit samples
    // This is how these fields are defined, no harm to assert that they're what we expect
    assert(wav->blockAlign == wav->numChannels * wav->bitsPerSample/8);
    assert(wav->byteRate == wav->sampleRate * wav->blockAlign);

    uint32_t numWavSamples = wav->dataChunkSize / sizeof(uint16_t);
    uint16_t* wavSamples = wav->samples;

    HRESULT hr = CoInitializeEx(nullptr, COINIT_SPEED_OVER_MEMORY);
    assert(hr == S_OK);

    IMMDeviceEnumerator* deviceEnumerator;
    hr = CoCreateInstance(__uuidof(MMDeviceEnumerator), nullptr, CLSCTX_ALL, __uuidof(IMMDeviceEnumerator), (LPVOID*)(&deviceEnumerator));
    assert(hr == S_OK);

    IMMDevice* audioDevice;
    hr = deviceEnumerator->GetDefaultAudioEndpoint(eRender, eConsole, &audioDevice);
    assert(hr == S_OK);

    deviceEnumerator->Release();

    IAudioClient2* audioClient;
    hr = audioDevice->Activate(__uuidof(IAudioClient2), CLSCTX_ALL, nullptr, (LPVOID*)(&audioClient));
    assert(hr == S_OK);

    audioDevice->Release();
    
    // WAVEFORMATEX* defaultMixFormat = NULL;
    // hr = audioClient->GetMixFormat(&defaultMixFormat);
    // assert(hr == S_OK);

    WAVEFORMATEX mixFormat = {};
    mixFormat.wFormatTag = WAVE_FORMAT_PCM;
    mixFormat.nChannels = 2;
    mixFormat.nSamplesPerSec = 44100;//defaultMixFormat->nSamplesPerSec;
    mixFormat.wBitsPerSample = 16;
    mixFormat.nBlockAlign = (mixFormat.nChannels * mixFormat.wBitsPerSample) / 8;
    mixFormat.nAvgBytesPerSec = mixFormat.nSamplesPerSec * mixFormat.nBlockAlign;

    const float BUFFER_SIZE_IN_SECONDS = 2.0f;
    const int64_t REFTIMES_PER_SEC = 10000000; // hundred nanoseconds
    REFERENCE_TIME requestedSoundBufferDuration = (REFERENCE_TIME)(REFTIMES_PER_SEC * BUFFER_SIZE_IN_SECONDS);
    DWORD initStreamFlags = ( AUDCLNT_STREAMFLAGS_RATEADJUST 
                            | AUDCLNT_STREAMFLAGS_AUTOCONVERTPCM
                            | AUDCLNT_STREAMFLAGS_SRC_DEFAULT_QUALITY );
    hr = audioClient->Initialize(AUDCLNT_SHAREMODE_SHARED, 
                                 initStreamFlags, 
                                 requestedSoundBufferDuration, 
                                 0, &mixFormat, nullptr);
    assert(hr == S_OK);

    IAudioRenderClient* audioRenderClient;
    hr = audioClient->GetService(__uuidof(IAudioRenderClient), (LPVOID*)(&audioRenderClient));
    assert(hr == S_OK);

    UINT32 bufferSizeInFrames;
    hr = audioClient->GetBufferSize(&bufferSizeInFrames);
    assert(hr == S_OK);

    hr = audioClient->Start();
    assert(hr == S_OK);

    int wavPlaybackSample = 0;
    while (true)
    {
        // Padding is how much valid data is queued up in the sound buffer
        // if there's enough padding then we could skip writing more data
        UINT32 bufferPadding;
        hr = audioClient->GetCurrentPadding(&bufferPadding);
        assert(hr == S_OK);

        // How much padding we want our sound buffer to have after writing to it.
        // Needs to be enough so that the playback doesn't reach garbage data
        // but we get less latency the lower it is (i.e. how long does it take
        // between pressing jump and hearing the sound effect)
        // Try setting this to e.g. 1/250.f to hear what happens when
        // we're not writing enough data to stay ahead of playback!
        const float TARGET_BUFFER_PADDING_IN_SECONDS = 1/60.f;
        UINT32 targetBufferPadding = UINT32(bufferSizeInFrames * TARGET_BUFFER_PADDING_IN_SECONDS);
        UINT32 numFramesToWrite = targetBufferPadding - bufferPadding;

        int16_t* buffer;
        hr = audioRenderClient->GetBuffer(numFramesToWrite, (BYTE**)(&buffer));
        assert(hr == S_OK);

        for (UINT32 frameIndex = 0; frameIndex < numFramesToWrite; ++frameIndex)
        {
            *buffer++ = wavSamples[wavPlaybackSample++]; // left
            *buffer++ = wavSamples[wavPlaybackSample++]; // right
            wavPlaybackSample %= numWavSamples; // Loop if we reach end of wav file
        }
        hr = audioRenderClient->ReleaseBuffer(numFramesToWrite, 0);
        assert(hr == S_OK);

        // Get playback cursor position
        // This is good for visualising playback and seeing the reading/writing in action!
        IAudioClock* audioClock;
        audioClient->GetService(__uuidof(IAudioClock), (LPVOID*)(&audioClock));
        UINT64 audioPlaybackFreq;
        UINT64 audioPlaybackPos;
        audioClock->GetFrequency(&audioPlaybackFreq);
        audioClock->GetPosition(&audioPlaybackPos, 0);
        audioClock->Release();
        // UINT64 audioPlaybackPosInSeconds = audioPlaybackPos/audioPlaybackFreq;
        // UINT64 audioPlaybackPosInSamples = audioPlaybackPosInSeconds*mixFormat.nSamplesPerSec;
    }

    audioClient->Stop();
    audioClient->Release();
    audioRenderClient->Release();

    Win32FreeFileData(fileBytes);

    return 0;
}

I know it's been a while and I'm not sure if this is he issue @onigumo69 was referring to, but in this code sample the audio seems to play at half speed. After some debugging I managed to figure out that this is due to the samples per second in the WAVEFORMATEX struct not accounting for stereo input data on line 126, and being set to half the sampling rate required.
After changing mixFormat.nSamplesPerSec = 44100 to mixFormat.nSamplesPerSec = 44100 * 2 it plays at full speed and normally, but you also have to change wavPlaybackSample %= numWavSamples to wavPlaybackSample %= numWavSamples * 2 on line 184 to read through the entire input buffer and not have the audio loop halfway through.
Hopefully this is of some help !

Thanks for looking into this, you were exactly right about there being a playback speed bug. I have a different fix to yours though - We shouldn't mess with the mix format we're giving Windows to for rendering, so instead I'll change the line: uint32_t numWavSamples = wav->dataChunkSize / (wav->numChannels * sizeof(uint16_t)); to: uint32_t numWavSamples = wav->dataChunkSize / sizeof(uint16_t);

This is the actual bug, I was calculating number of samples per channel but treating it as the overall number of samples later in the code. Revision coming soon, thanks again for your help, and to onigumo69 for reporting (apologies I didn't get fixing it till now).

I'm glad it helped! That's definitely a way more elegant solution, it seems like I really wasn't keeping the bigger picture in mind. I'll have to update this in the code I adapted, this solution is way more flexible when it comes to the amount of channels in the wave file.

good stuff guys