User guide

Note: Apple recommends that apps using voice or video chat also use the Voice-Processing

I/O audio unit. The Voice-Processing I/O unit provides several features for VOIP apps, including

automatic gain correction, adjustment of voice-processing, and muting. See Voice-Processing

I/O Unit for more information.

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AVAudioSessionModeGameChat—For game apps. This mode is set automatically by apps that use a

GKVoiceChat object and the AVAudioSessionCategoryPlayAndRecord category. Game chat mode

uses the same routing parameters as the video chat mode.

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AVAudioSessionModeVideoRecording—For apps that use the camera to capture video. The video

recording mode can be used only with the AVAudioSessionCategoryPlayAndRecord and

AVAudioSessionCategoryRecord categories. Signals are modified by system-supplied signal processing.

Use the AVCaptureSession API in conjunction with the video recording mode for greater control of

input and output routes. For example, setting the

automaticallyConfiguresApplicationAudioSession property automatically chooses the best

input route depending on the device and camera used.

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AVAudioSessionModeMeasurement—For apps that need to minimize the amount of system-supplied

signal processing to input and output signals. This mode can only be used with the following categories:

record, play-and-record, and playback. Input signals are routed through the primary microphone for the

device.

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AVAudioSessionModeMoviePlayback—For apps that play movies. This mode can be used only with

the AVAudioSessionCategoryPlayback category.

Choosing Categories and Modes for AirPlay

Only specific categories and modes support AirPlay. The following categories support both the mirrored and

non-mirrored versions of Airplay:

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AVAudioSessionCategorySoloAmbient

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AVAudioSessionCategoryAmbient

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AVAudioSessionCategoryPlayback

The AVAudioSessionCategoryPlayAndRecord category only supports mirrored Airplay.

Modes only support AirPlay when used in conjunction with the play-and-record category. The following modes

support AirPlay mirroring only:

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AVAudioSessionModeDefault

Working with Categories

Choosing Categories and Modes for AirPlay