Audio Devices in UCMA 2.0 Core
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The topics in this section describe the audio devices that are available in Microsoft Unified Communications Managed API 2.0 Core SDK: Player, Recorder, ToneController, SpeechRecognitionConnector, and SpeechSynthesisConnector. These devices, respectively, can be used to play recorded audio, record audio, send and receive telephone dial tones, convert speech to text, or convert text to speech.
In Unified Communications Managed API 2.0 Core SDK, devices are users of media data, and have AudioVideoFlow instances attached to them. Although these devices are represented as properties on the AudioVideoFlow class, they are not automatically instantiated and each device is independent of the AudioVideoFlow instance that is attached to it. Before any of these devices can be used, it must be created, and then attached to an AudioVideoFlow instance. Although most of the devices are associated with a single AudioVideoFlow instance, a Player device can have multiple AudioVideoFlow instances attached to it. In addition, an AudioVideoFlow instance can be detached from a given Player, and another AudioVideoFlow instance can be attached.
The following code example shows the steps required to create a Player and attach an existing AudioVideoFlow instance to it.
Player myPlayer = new Player();
myPlayer.AttachFlow(avFlow);
Each of the devices has an AttachFlow method that it uses to attach an AudioVideoFlow instance. Simillarly, each device has a DetachFlow method that it uses to detach the previously-attached AudioVideoFlow instance. The AttachFlow and DetachFlow operations can happen at any time, independent of the state of the AudioVideoFlow instance.
Except for a Player device, a given AudioVideoFlow instance can be attached to only one device at a time. The AudioVideoFlow can remove the channel spontaneously if the Real-Time Protocol (RTP) connection is broken or if the far end requests a hold or renegotiation.
When a device is shut down, the attached AudioVideoFlow is not automatically detached. The AudioVideoFlow remains attached until it is detached. The AudioVideoFlow must eventually be detached, or a memory leak will result. A long-lived device such as a Player can have many flows attached to it, and each flow and all related objects remain in memory even when the Player is shut down.
This section contains the following topics: