Wwise SDK 2024.1.4

Offline Rendering

The Wwise Sound Engine offers offline rendering that allows for non-real-time, compute-intensive audio generation and the synchronization of audio processing with compute-intensive video generation.

warning Caution: Care must be taken when enabling offline rendering in applications that use the synchronous AK::SoundEngine::LoadBank and AK::SoundEngine::UnloadBank APIs. See Audio Rendering Thread for details.

An audio capture callback can be registered using AK::SoundEngine::RegisterCaptureCallback, which provides a mechanism for accessing the rendered audio buffers.

The following is an example that illustrates one possible implementation of offline rendering:

/// Video capture services accessible in the game code
namespace VideoCaptureServices
{
    /// Possibly allocates buffers for video capture
    void Initialize();
    
    /// Possibly outputs captured video and audio as a movie file
    void Finalize();
 
    /// Possibly captures a single video frame buffer to a file.
    void CaptureSingleFrame();
}
 
/// Audio capture services accessible in the game code
namespace AudioCaptureServices
{
    /// Allocates buffers or opens files for the eventual capture of audio samples.
    void Initialize(unsigned in_uSampleRate, unsigned in_uChannels);
 
    /// Releases buffers or file handles once audio sample capture is completed.
    void Finalize();
 
    /// Adds audio samples to the allocated buffers
    void CaptureInterleavedSamples(float* in_pfSamples, unsigned in_uSampleCount);
}
 
class GameInterface
{
    // ...
 
public:
    /// Function called once per game frame
    virtual void UpdateCallback(float deltaTime //< elapsed wall clock time in real-time, inverse of the desired frame rate in offline mode
        ) = 0;
};
 
class Game : public GameInterface
{
    // ...
 
private:
    /// True when offline rendering is enabled.
    bool m_bIsOfflineRendering{ false };
 
    /// Output device ID for registration/unregistration of capture callback.
    AkOutputDeviceID m_defaultOutputDeviceId{ AK_INVALID_OUTPUT_DEVICE_ID };
 
    /// Wwise audio capture callback.
    static void CaptureCallback(AkAudioBuffer& in_CaptureBuffer, AkOutputDeviceID /*in_idOutput*/, void* /*in_pCookie*/)
    {
        const unsigned uSampleCount = static_cast<unsigned>(in_CaptureBuffer.uValidFrames) * in_CaptureBuffer.NumChannels();
        if (!uSampleCount)
            return;
 
        AudioCaptureServices::CaptureInterleavedSamples(in_CaptureBuffer.GetInterleavedData(), uSampleCount);
    }
 
public:
    /// Function called to enable/disable offline rendering
    void SetOfflineRendering(bool bIsOfflineRendering //< true for offline rendering, and false for real-time rendering
        )
    {
        const bool bWasOfflineRendering{ m_bIsOfflineRendering };
        m_bIsOfflineRendering = bIsOfflineRendering;
 
        // Posts a message on the message queue to enable/disable offline rendering
        AK::SoundEngine::SetOfflineRendering(m_bIsOfflineRendering);
 
        if (m_bIsOfflineRendering == bWasOfflineRendering)
            return;
 
        // Posts a message on the message queue to set the offline rendering frame time to zero ensuring that the subsequent call to RenderAudio() will not generate more audio samples.
        AK::SoundEngine::SetOfflineRenderingFrameTime(0.0f);
 
        // Call RenderAudio() to flush the message queue. After this call, offline rendering will be enabled/disabled.
        AK::SoundEngine::RenderAudio();
 
        if (m_bIsOfflineRendering)
        {
            VideoCaptureServices::Initialize();
 
            // When engaging offline rendering, the output configuration will switch to Stereo output by default
            // In order to render to a different output speaker layout, replace the output with an explicitly defined one.
            // In this example, switch to 7.1.4
            AkChannelConfig surroundConfig;
            surroundConfig.SetStandard(AK_SPEAKER_SETUP_DOLBY_7_1_4);
 
            // Post a mesage to replace the output device.
            AkOutputSettings newSettings;
            newSettings.audioDeviceShareset = AK::AUDIO_DEVICES::SYSTEM;
            newSettings.idDevice = 0;
            newSettings.ePanningRule = AkPanningRule_Speakers;
            newSettings.channelConfig = surroundConfig;
            AK::SoundEngine::ReplaceOutput(newSettings, 0, &m_defaultOutputDeviceId);
        
            // Flush the message queue again to make sure ReplaceOutput is processed, before registering the capture callback on the offline device
            AK::SoundEngine::RenderAudio(true);
 
            const AkUInt32 uSampleRate{ AK::SoundEngine::GetSampleRate() };
 
            // Provide the sample rate and number of channels to allocate the appropriate buffers.
            AudioCaptureServices::Initialize(uSampleRate, surroundConfig.uNumChannels);
 
            AK::SoundEngine::RegisterCaptureCallback(&CaptureCallback, m_defaultOutputDeviceId, this);
        }
        else
        {
            AK::SoundEngine::UnregisterCaptureCallback(&CaptureCallback, m_defaultOutputDeviceId, this);
 
            AudioCaptureServices::Finalize();
            VideoCaptureServices::Finalize();
        }
    }
 
    void UpdateCallback(float deltaTime) override
    {
        if (m_bIsOfflineRendering)
            AK::SoundEngine::SetOfflineRenderingFrameTime(deltaTime);
 
        AK::SoundEngine::RenderAudio();
 
        if (m_bIsOfflineRendering)
            VideoCaptureServices::CaptureSingleFrame();
    }
};

AK::SoundEngine::GetSampleRate

AKSOUNDENGINE_API AkUInt32 GetSampleRate()

AkOutputSettings::ePanningRule

AkPanningRule ePanningRule

Definition: AkSoundEngine.h:147

AkChannelConfig::uNumChannels

AkUInt32 uNumChannels

Number of channels.

Definition: AkSpeakerConfig.h:449

AkAudioBuffer::NumChannels

AkForceInline AkUInt32 NumChannels() const

Get the number of channels.

Definition: AkCommonDefs.h:348

AkChannelConfig

Definition: AkSpeakerConfig.h:444

AkOutputSettings

Platform-independent initialization settings of output devices.

Definition: AkSoundEngine.h:123

AK::SoundEngine::SetOfflineRenderingFrameTime

AKSOUNDENGINE_API AKRESULT SetOfflineRenderingFrameTime(AkReal32 in_fFrameTimeInSeconds)

AK::SoundEngine::ReplaceOutput

AKSOUNDENGINE_API AKRESULT ReplaceOutput(const AkOutputSettings &in_Settings, AkOutputDeviceID in_outputDeviceId, AkOutputDeviceID *out_pOutputDeviceId=NULL)

AkAudioBuffer::uValidFrames

AkUInt16 uValidFrames

Number of valid sample frames in the audio buffer.

Definition: AkCommonDefs.h:513

AK_SPEAKER_SETUP_DOLBY_7_1_4

#define AK_SPEAKER_SETUP_DOLBY_7_1_4

Dolby 7.1.4 setup channel mask.

Definition: AkSpeakerConfig.h:110

AK::SoundEngine::RegisterCaptureCallback

AKSOUNDENGINE_API AKRESULT RegisterCaptureCallback(AkCaptureCallbackFunc in_pfnCallback, AkOutputDeviceID in_idOutput=AK_INVALID_OUTPUT_DEVICE_ID, void *in_pCookie=NULL)

AK::SoundEngine::RenderAudio

AKSOUNDENGINE_API AKRESULT RenderAudio(bool in_bAllowSyncRender=true)

AK::SoundEngine::UnregisterCaptureCallback

AKSOUNDENGINE_API AKRESULT UnregisterCaptureCallback(AkCaptureCallbackFunc in_pfnCallback, AkOutputDeviceID in_idOutput=AK_INVALID_OUTPUT_DEVICE_ID, void *in_pCookie=NULL)

AK_INVALID_OUTPUT_DEVICE_ID

static const AkUInt32 AK_INVALID_OUTPUT_DEVICE_ID

Invalid Device ID.

Definition: AkTypes.h:110

AkPanningRule_Speakers

@ AkPanningRule_Speakers

Left and right positioned 60 degrees apart (by default - see AK::SoundEngine::GetSpeakerAngles()).

Definition: AkTypes.h:1152

AK::SoundEngine::SetOfflineRendering

AKSOUNDENGINE_API AKRESULT SetOfflineRendering(bool in_bEnableOfflineRendering)

AkOutputSettings::idDevice

AkUInt32 idDevice