Wwise SDK 2021.1.9
Offline Rendering with Wwise

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.

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
// ...
/// Function called once per game frame
virtual void UpdateCallback(float deltaTime //< the elapsed time - wall clock time in real-time, approximately calculated in offline
) = 0;
class Game : public GameInterface
// ...
/// 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)
AudioCaptureServices::CaptureInterleavedSamples(in_CaptureBuffer.GetInterleavedData(), uSampleCount);
/// 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
if (m_bIsOfflineRendering == bWasOfflineRendering)
// 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.
// Call RenderAudio() to flush the message queue. After this call, offline rendering will be enabled/disabled.
if (m_bIsOfflineRendering)
// Cache the output device ID for unregistration.
m_defaultOutputDeviceId = AK::SoundEngine::GetOutputID(AK_INVALID_UNIQUE_ID, 0);
AkChannelConfig channelConfig{};
Ak3DAudioSinkCapabilities audioSinkCapabilities{};
// Obtain the number of channels.
AK::SoundEngine::GetOutputDeviceConfiguration(m_defaultOutputDeviceId, channelConfig, audioSinkCapabilities);
const AkUInt32 uSampleRate{ AK::SoundEngine::GetSampleRate() };
// Provide the sample rate and number of channels to allocate the appropriate buffers.
AudioCaptureServices::Initialize(uSampleRate, channelConfig.uNumChannels);
AK::SoundEngine::RegisterCaptureCallback(&CaptureCallback, m_defaultOutputDeviceId, this);
AK::SoundEngine::UnregisterCaptureCallback(&CaptureCallback, m_defaultOutputDeviceId, this);
void UpdateCallback(float deltaTime) override
if (m_bIsOfflineRendering)
if (m_bIsOfflineRendering)
AkForceInline AkUInt32 NumChannels() const
Get the number of channels.
Definition: AkCommonDefs.h:465
AKSOUNDENGINE_API AKRESULT SetOfflineRenderingFrameTime(AkReal32 in_fFrameTimeInSeconds)
AkUInt16 uValidFrames
Number of valid sample frames in the audio buffer.
Definition: AkCommonDefs.h:630
AKSOUNDENGINE_API AkOutputDeviceID GetOutputID(AkUniqueID in_idShareset, AkUInt32 in_idDevice)
AKSOUNDENGINE_API AKRESULT GetOutputDeviceConfiguration(AkOutputDeviceID in_idOutput, AkChannelConfig &io_channelConfig, Ak3DAudioSinkCapabilities &io_capabilities)
AKSOUNDENGINE_API AKRESULT RegisterCaptureCallback(AkCaptureCallbackFunc in_pfnCallback, AkOutputDeviceID in_idOutput=AK_INVALID_OUTPUT_DEVICE_ID, void *in_pCookie=NULL)
AKSOUNDENGINE_API AKRESULT RenderAudio(bool in_bAllowSyncRender=true)
AKSOUNDENGINE_API AKRESULT UnregisterCaptureCallback(AkCaptureCallbackFunc in_pfnCallback, AkOutputDeviceID in_idOutput=AK_INVALID_OUTPUT_DEVICE_ID, void *in_pCookie=NULL)
Invalid Device ID.
Definition: AkTypes.h:109
static const AkUniqueID AK_INVALID_UNIQUE_ID
Invalid unique 32-bit ID.
Definition: AkTypes.h:97
AKSOUNDENGINE_API AKRESULT SetOfflineRendering(bool in_bEnableOfflineRendering)
uint32_t AkUInt32
Unsigned 32-bit integer.
Definition: AkTypes.h:59
AkUInt64 AkOutputDeviceID
Audio Output device ID.
Definition: AkTypes.h:89
AkForceInline void * GetInterleavedData()
Definition: AkCommonDefs.h:487