# Development Guidelines on Audio Management ## When to Use You use audio management APIs to set and obtain volume, and get information about input/output devices. ## Available APIs **Table 1** APIs for audio management

API	Description
getAudioManager(): AudioManager	Obtains an AudioManager instance.
AudioManager	Manages audio volume and audio device information. For details, see AudioManager.
AudioDeviceDescriptor	Describes audio devices.
AudioVolumeType	Enumerates audio volume types.
DeviceFlag	Enumerates flags of supported devices.
DeviceRole	Enumerates device roles.
DeviceType	Enumerates device types.

**Table 2** AudioManager methods

Method	Description
setVolume(audioType: AudioVolumeType,volume: number,callback: AsyncCallback<void>): void	Sets the volume of a stream asynchronously and uses a callback to return the execution result.
setVolume(audioType: AudioVolumeType,volume: number): Promise<void>	Sets the volume of a stream asynchronously and uses a Promise to return the execution result.
getVolume(audioType: AudioVolumeType, callback: AsyncCallback<number>): void	Obtains the volume of a stream asynchronously and uses a callback to return the execution result.
getVolume(audioType: AudioVolumeType): Promise<number>	Obtains the volume of a stream asynchronously and uses a Promise to return the execution result.
getMinVolume(audioType: AudioVolumeType, callback: AsyncCallback<number>): void	Obtains the minimum volume of a stream asynchronously and uses a callback to return the execution result.
getMinVolume(audioType: AudioVolumeType): Promise<number>	Obtains the minimum volume of a stream asynchronously and uses a Promise to return the execution result.
getMaxVolume(audioType: AudioVolumeType, callback: AsyncCallback<number>): void	Obtains the maximum volume of a stream asynchronously and uses a callback to return the execution result.
getMaxVolume(audioType: AudioVolumeType): Promise<number>	Obtains the maximum volume of a stream asynchronously and uses a Promise to return the execution result.
getDevices(deviceFlag: DeviceFlag, callback: AsyncCallback<AudioDeviceDescriptors>): void	Obtains the device list asynchronously and uses a callback to return the execution result.
getDevices(deviceFlag: DeviceFlag): Promise<AudioDeviceDescriptors>	Obtains the device list asynchronously and uses a Promise to return the execution result.

**Table 3** AudioDeviceDescriptor attributes

Parameter	Description
deviceRole: DeviceRole	Audio device role
deviceType: DeviceType	Audio device type

**Table 4** AudioVolumeType enums

Enum	Description
MEDIA = 1	Audio streams for media purpose
RINGTONE = 2	Audio streams for ring tones

**Table 5** DeviceFlag enums

Enum	Description
OUTPUT_DEVICES_FLAG = 1	Output devices
INPUT_DEVICES_FLAG = 2	Input devices
ALL_DEVICES_FLAG = 3	All devices

**Table 6** DeviceRole enums

Enum	Description
INPUT_DEVICE = 1	Input role
OUTPUT_DEVICE = 2	Output role

**Table 7** DeviceType enums

Enum	Description
INVALID = 0	Invalid device
SPEAKER = 1	Speaker
WIRED_HEADSET = 2	Wired headset
BLUETOOTH_SCO = 3	Bluetooth device using the synchronous connection oriented link (SCO)
BLUETOOTH_A2DP = 4	Bluetooth device using advanced audio distribution profile (A2DP)
MIC = 5	Microphone

## Development Procedure 1. Obtain an audio manager. ``` const audioManager = audio.getAudioManager(); ``` 2. Set the audio stream volume. ``` audioManager.getVolume(audio.AudioVolumeType.MEDIA, (err, value) => { if (err) { console.error(`failed to get volume ${err.message}`); return; } console.log(`Media getVolume ${value}`); }); ```