Core Audio API Emilis Armonas

About These APIs were new in Windows Vista and are not available in earlier versions of Windows. The core audio APIs provide the means for audio applications to access audio endpoint devices such as headphones and microphones. The core audio APIs serve as the foundation for higher-level audio APIs such as Microsoft DirectSound and the Windows multimedia waveXxx functions Most applications communicate with the higher-level APIs, but some applications with special requirements might need to communicate directly with the core audio APIs.

Audio capabilities Low-latency Improved reliability Improved security Assignment of particular system-wide roles Software abstraction of the audio endpoint devices This is a new set of user-mode audio components provides client applications with improved audio capabilities. These capabilities include the following: Low-latency, glitch-resilient audio streaming. Improved reliability (many audio functions have moved from kernel mode to user mode). Improved security (processing of protected audio content takes place in a secure, lower-privilege process). Assignment of particular system-wide roles (console, multimedia, and communications) to individual audio devices. Software abstraction of the audio endpoint devices (for example, speakers, headphones, and microphones) that the user manipulates directly.

Higher-level APIs DirectSound DirectMusic Windows multimedia waveXxx and mixerXxx functions Media Foundation These higher-level APIs use the Core Audio APIs to share access to audio devices. Media Foundation is new with Windows Vista, whereas DirectSound, DirectMusic, and the waveXxx and mixerXxx functions are supported in Windows 98, Windows Millennium Edition, and in Windows 2000 and later. Most audio applications communicate with the higher-level APIs instead of communicating directly with the Core Audio APIs. Some examples of applications that use higher-level APIs are: Media players DVD players Games Business applications, such as Microsoft Office PowerPoint, that play sound files Typically, these applications communicate with the DirectSound or Media Foundation APIs.

Main Core Audio APIs Multimedia Device (MMDevice) API. Clients use this API to enumerate the audio endpoint devices in the system. Windows Audio Session API (WASAPI). Clients use this API to create and manage audio streams to and from audio endpoint devices. DeviceTopology API. Clients use this API to directly access the topological features (for example, volume controls and multiplexers) that lie along the data paths inside hardware devices in audio adapters. EndpointVolumeAPI. Clients use this API to directly access the volume controls on audio endpoint devices. This API is primarily used by applications that manage exclusive-mode audio streams. Multimedia Device (MMDevice) API – naudojamas garso įrenginių išvardijimui. Windows Audio Session API (WASAPI) – naudojamas garso srautų kūrimui ir valdymui. DeviceTopology API – naudojamas tiesiogiai pasiekti topologines funkcijas, esančias techninėje įrangoje (pvz. garsumo valdikliai ir multiplekseriai). EndpointVolume API – naudojamas tiesiogiai pasiekti garso valdiklius garso prietaisuose

Multimedia Device (MMDevice) API The Windows Multimedia Device (MMDevice) API enables audio clients to discover audio endpoint device, determine their capabilities, and create driver instances for those devices. Šis API randa garso išvesties ir įvesties įrenginius, nustatyto jų charakteristikas ir kuria tvarkykles šiems įrenginiams.

Windows Audio Session API (WASAPI) The Windows Audio Session API (WASAPI) enables client applications to manage the flow of audio data between the application and an audio endpoint device. Through the session abstraction, a WASAPI client can identify an audio stream as a member of a group of related audio streams. The system can manage all of the streams in the session as a single unit. WASAPI leidžia kleinto programoms valdyti garso srautus tarp programos ir garso įrenginių. WASAPI identifikuoja garso srautus kaip dalį garsų sesijos. Tai leidžia sistemai valdyti visus sesijos srautus kaip visumą.

DeviceTopology API The DeviceTopology API provides client applications with the ability to traverse the functional hardware topologies of audio rendering and capture devices. Through the interfaces and methods in the DeviceTopology API, clients can discover the functional subunits (for example, volume control) that lie along the data paths that lead to and from audio enpoints devices. Clients can traverse the internal topologies of both audio adapter devices and audio endpoint devices and step across the connections that link one device to another DeviceTopologyAPI susieja funkcinę aparatinę įrangą ir garso perteikimo prietaisus. DeviceTopology klientai gali valdyti funkcinius subvienetus (pvz. garsumo kontrolė) garso įvesties ir išvesties įrenginiuose. Programos gali pereiti per vidinius garso adapterius ir garso įrenginius bei valdyti ryšį, jungiantį vieną prietaisą su kitu.

EndpointVolumeAPI The EndpointVolume API enables specialized clients to control and monitor the volume levels of audio endpoint devices. Inappropriate use of the EndpointVolume API can interfere with Windows audio policy and disrupt the user's system volume settings. EndpointVolume API leidžia kontroliuoti ir stebėti garso lygius garso išvesties įrenginiuose. Netinkamas šio API naudojimas gali pažeisti Windows garso politiką ir sutrikdyti vartotojo garso nustatymus.

Thanks for your attention!