> ## Documentation Index
> Fetch the complete documentation index at: https://devdocs.xbox.com/llms.txt
> Use this file to discover all available pages before exploring further.

# Overview of spatial sound

> Add Dolby Atmos, DTS:X, and Windows Sonic spatial audio to XBOX games, including hardware object counts for XBOX Series X|S and XBOX One.

Use spatial sound audio support to add Dolby Atmos for home theater, Dolby Atmos for Headphones, DTS:X for home theater, DTS Headphone:X, and Windows Sonic for Headphones support (more coming soon) to your streaming media application or game. Spatial sound audio includes the following:

* Rendering of elevation cues to speaker systems that support these products, such as Dolby Atmos receivers
* Psychoacoustic processing for spatialization on headsets, such as Microsoft head-related transfer function (HRTF) technologies (originally developed by Microsoft HoloLens)

The XBOX One and XBOX Series X|S family of consoles use hardware acceleration for spatial audio technologies and hence the cost of spatial processing on the CPU is minimal. A major improvement has been made to the maximum dynamic object counts for spatial headset formats on the XBOX Series X|S, specifically for games utilizing the 2303 or later Game Development Kit (GDK). Windows Sonic now supports 220 dynamic objects, Dolby Atmos for headphones has been boosted to 128 and DTS Headphone:X now supports 200 dynamic objects. These advancements bring an elevated level of immersive audio experience to the players.

The maximum number of dynamic spatial objects in HDMI remains unchanged for Dolby Atmos for home theater. However, there is an increase from 16 to 20 dynamic objects for DTS:X for home theater exclusively for XBOX Series X|S, when the title utilizes 2303 or later GDK. These values can be obtained through the [ISpatialAudioClient::GetMaxDynamicObjectCount](https://learn.microsoft.com/windows/win32/api/spatialaudioclient/nf-spatialaudioclient-ispatialaudioclient-getmaxdynamicobjectcount) method. Please see [Spatial Sound](https://learn.microsoft.com/windows/win32/coreaudio/spatial-sound) on Microsoft Learn for more information on spatial audio and the maximum number of dynamic objects supported on each platform.

To test titles using older GDKs, copy an empty file named "ForceCFPU2SpatialOffload" (with no extension) to the root of d: drive (shows as SystemScratch on XBOX Manager) on the XBOX Series X|S devkit console. This mimics the behavior of GetMaxDynamicObjectCount that returns the higher dynamic object counts as if the title is using 2303 GDK.

The [AdvancedSpatialSounds](https://aka.ms/gdkdl) sample demonstrates how to use [ISpatialAudioClient](https://msdn.microsoft.com/library/windows/desktop/mt779259\(v=vs.85\).aspx) to play back both static and dynamic positional audio by using Windows Sonic and other spatial technologies. The static bed plays on startup, and dynamic sounds that follow random paths can be added and removed.

On Windows, they scale according to the capabilities of an individual format or PC. Rendering engines and audio middleware typically use the [ISpatialAudioClient](https://msdn.microsoft.com/library/windows/desktop/mt779259\(v=vs.85\).aspx) (ISAC) API directly. However, many titles leverage spatial capabilities via digital signal processing (DSP) plug-ins to the audio engines that they already use today.

ISAC is a spatial audio sink that abstracts spatial audio formats (such as height speakers and psychoacoustic headset encoding) from the concept of positioned sound objects, which are managed by the game. ISAC supports dynamic, user-specified switching between output and encoding formats; a virtual surround sound downmix fallback when spatial output isn't available; and simultaneous playback of multiple spatial and non-spatial clients, such as Windows Audio Session API (WASAPI). Typically, ISAC is accessed by titles as a wrapped audio middleware plug-in. However, titles that implement their own audio rendering engines might use ISAC directly.

Spatial sound audio capabilities and support specifications are shown in the following table.

| Feature                       | Capability/support                                                                                                                                                                                                                                                                             |
| ----------------------------- | ---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |
| Operating systems             | XBOX family: XBOX One, XBOX One S, and XBOX One X, XBOX Series X\|S.<br />Windows 10: Win32 desktop and Universal Windows Platform (UWP).                                                                                                                                                      |
| Audio output formats          | Dolby Atmos: speakers and headsets.<br /> DTS:X: speakers and headsets<br /> Microsoft HRTF: headsets.                                                                                                                                                                                         |
| Audio input formats           | Mono channels and objects, fixed at 48 KHz float. Audio engines can sample rate conversion from other formats at input.                                                                                                                                                                        |
| Sound object formats          | Flexible channel bed (up to 7.1.4), and multiple dynamic spatial audio objects.                                                                                                                                                                                                                |
| Spatial audio object capacity | Please visit [Spatial Sound](https://learn.microsoft.com/windows/win32/coreaudio/spatial-sound) on MSDN for detailed information on spatial audio object capacity for all platforms.                                                                                                           |
| Downmix behavior              | When spatial audio isn't available, such as in a stereo TV, the channel bed is virtual surround sound-downmixed and zero available dynamic objects are reported to the title.                                                                                                                  |
| CPU cost                      | Windows 10: TBD<br /> XBOX One & XBOX Series X\|S family: hardware-accelerated encoding for Dolby Atmos and Microsoft HRTF.<br />Depending on audio processing and the custom DSP effect used, other use of the CPU might increase, such as during the transition from stereo to 7.1.4 reverb. |
| Storage/file IO cost          | For prerendered cut scenes, 7.1.4 assets are likely to be larger than those that preceded 5.1 or 7.1.                                                                                                                                                                                          |

Recommendations for studio hardware are shown in the following table.

\| Device| Capability/support|
\| --- | --- | --- | --- |
\| Audio receiver| Dolby Atmos or DTS:X capable receiver (or soundbar) that supports a channel output of at least 5.1.2, but preferably 7.1.4 |
\| Speakers| 5.1.2 or 7.1.4 speakers, or speakers that are integrated with the receiver in the sound bar|
\| Headsets| Any stereo headsets; spatialization occurs in software|
\| Digital audio workstation| Elevation channels and height panners for authoring linear and prerendered audio content|

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## Related topics

[Spatial Sound](https://msdn.microsoft.com/library/windows/desktop/mt807491\(v=vs.85\).aspx)

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## See also

[ISpatialAudioClient interface](https://msdn.microsoft.com/library/windows/desktop/mt779259\(v=vs.85\).aspx)

[ISpatialAudioObject interface](https://msdn.microsoft.com/library/windows/desktop/mt779268\(v=vs.85\).aspx)

[ISpatialAudioObjectForHrtf interface](https://msdn.microsoft.com/library/windows/desktop/mt779269\(v=vs.85\).aspx)

[ISpatialAudioObjectRenderStream interface](https://msdn.microsoft.com/library/windows/desktop/mt779280\(v=vs.85\).aspx)

[ISpatialAudioObjectRenderStreamForHrtf interface](https://msdn.microsoft.com/library/windows/desktop/mt779297\(v=vs.85\).aspx)

[ISpatialAudioObjectRenderStreamNotify interface](https://msdn.microsoft.com/library/windows/desktop/mt779281\(v=vs.85\).aspx)


## Related topics

- [Overview of audio](/build/console-features/audio/overviews/audio.md)
- [Overviews](/build/console-features/audio/overviews/index.md)
- [Audio](/build/console-features/audio/gc-audio-toc.md)
- [Accessibility metadata](/publishing/game-publishing/concepts/metadata-accessibility.md)
- [XMA2STREAMFORMAT](/reference/audio/xma2defs/structs/xma2streamformat.md)
