PROTOCOLS
VolumePolicyController
Defined in fuchsia.settings.policy/volume_policy.fidl
Provides access to enumerating and modifying policies for the fuchsia.settings.Audio API.
Policies are automatically persisted across reboots and take effect again on boot.
AddPolicy
Adds a policy for the given target.
Returns a policy_id for the added policy, which can be used to remove the policy with RemovePolicy.
If the policy being added contradicts an existing policy, the add call will return an error. An example would be specifying a max volume for a stream that is lower than an existing min volume.
If the transform specified in the PolicyParameters is not enumerated in the available_transforms of the policy property, the connection will be closed.
Adding a policy will immediately adjust the audio setting values if they don't yet conform to the policy, such as reducing the volume if it's greater than a specified maximum volume.
Request
| Name | Type |
|---|---|
target |
Target
|
parameters |
PolicyParameters
|
Response
| Name | Type |
|---|---|
result |
VolumePolicyController_AddPolicy_Result
|
GetProperties
Gets a list of volume policy properties, including possible transforms and active policies for the property.
Request
<EMPTY>
Response
| Name | Type |
|---|---|
properties |
vector<Property>
|
RemovePolicy
Removes a policy with the given policy id.
Any client of this API can remove policies set by any other client.
Request
| Name | Type |
|---|---|
policy_id |
PolicyId
|
Response
| Name | Type |
|---|---|
result |
VolumePolicyController_RemovePolicy_Result
|
STRUCTS
VolumePolicyController_AddPolicy_Response
Defined in fuchsia.settings.policy/volume_policy.fidl
| Field | Type | Description | Default |
|---|---|---|---|
policy_id |
PolicyId
|
No default |
VolumePolicyController_RemovePolicy_Response
Defined in fuchsia.settings.policy/volume_policy.fidl
<EMPTY>
ENUMS
Error strict
Type: uint32
Defined in fuchsia.settings.policy/error.fidl
Common error code used across policies.
| Name | Value | Description |
|---|---|---|
FAILED |
1 |
Generic internal failure. |
UNKNOWN_POLICY |
2 |
The specified policy ID is not known. This may happen if another client removed a policy between a Get call and a RemovePolicy call. |
INVALID_POLICY |
3 |
The specified policy contradicts an existing policy. This may happen if another client added a policy between a Get call and an AddPolicy call. |
Transform strict
Type: uint8
Defined in fuchsia.settings.policy/volume_policy.fidl
Possible transforms for a policy target.
A transform is an operation that is applied to a policy property when the fuchsia.settings.Audio API is used. Multiple transforms of the same time can be active for a single property.
| Name | Value | Description |
|---|---|---|
MAX |
1 |
Limits the maximum value of an audio stream to a certain level. Max volume limits are transparent to clients of fuchsia.settings.Audio. Clients will always be able to set the volume to 1.0 (max) to prevent user confusion about not being able to set the volume to max. The internal volume, which is communicated to AudioCore to set the true volume level, will always be clamped to the specified maximum. Externally, the volume percentage will always be a percentage of the max allowed by policy. For example, if the max limit is set to 0.8, a client setting the volume to 1.0 translates to 0.8 internally. An external volume of 0.5 would be scaled to 0.4 internally. If a min volume limit is present, the minimum external volume will be the min volume limit divided by the max volume limit. For example, if the max volume limit is 0.8 and the min volume limit is 0.2, the lowest possible external volume is 0.25, since 0.2 is 25% of 0.8. The min range is not transparent to clients to prevent the confusion of volume being at 0% but still being able to hear audio. |
MIN |
2 |
Limits the minimum value of an audio stream to a certain level. If the volume is below the specified minimum level when the policy is added, it will automatically be raised to the specified minimum. Calls to set the volume below the minimum level will not fail, but the actual volume will stay above the specified minimum level. Note that the minimum volume limit is a limit on the internal "true" volume level. If a maximum volume policy is set, the minimum that clients of fuchsia.settings.Audio will see is higher. See the documentation of the MAX volume transform for more information. |
TABLES
Policy
Defined in fuchsia.settings.policy/volume_policy.fidl
Definition for a policy that is applied to the fuchsia.settings.Audio API.
| Ordinal | Field | Type | Description |
|---|---|---|---|
1 |
policy_id |
PolicyId
|
Unique identifier for this policy. Returned from AddPolicy and also used by RemovePolicy. |
2 |
parameters |
PolicyParameters
|
Parameters for this policy. |
Property
Defined in fuchsia.settings.policy/volume_policy.fidl
A controllable property of the fuchsia.settings.Audio API that can have transforms applied to it.
| Ordinal | Field | Type | Description |
|---|---|---|---|
1 |
target |
Target
|
Unique aspect of settings that this property controls. Only one property may control any given target. |
2 |
available_transforms |
vector<Transform>
|
List of available transform types for this property. |
3 |
active_policies |
vector<Policy>
|
List of active policies for this property. |
Volume
Defined in fuchsia.settings.policy/volume_policy.fidl
| Ordinal | Field | Type | Description |
|---|---|---|---|
1 |
volume |
float32
|
A volume between 0.0 and 1.0 inclusive. |
UNIONS
PolicyParameters strict
Defined in fuchsia.settings.policy/volume_policy.fidl
Specifies the type of policy transform and its arguments.
The chosen union field implies the type of transform that the arguments apply to.
| Ordinal | Variant | Type | Description |
|---|---|---|---|
1 |
min |
Volume
|
This parameter should be included for the MIN transform and specifies the volume level to clamp the audio stream to. |
2 |
max |
Volume
|
This parameter should be included for the MAX transform and specifies the volume level to clamp the audio stream to. |
Target strict
Defined in fuchsia.settings.policy/volume_policy.fidl
Specifies what aspect of the settings a property controls.
| Ordinal | Variant | Type | Description |
|---|---|---|---|
1 |
stream |
fuchsia.media/AudioRenderUsage
|
An audio stream that can have policies applied to it. |
VolumePolicyController_AddPolicy_Result strict
Defined in fuchsia.settings.policy/volume_policy.fidl
| Ordinal | Variant | Type | Description |
|---|---|---|---|
1 |
response |
VolumePolicyController_AddPolicy_Response
|
|
2 |
err |
Error
|
VolumePolicyController_RemovePolicy_Result strict
Defined in fuchsia.settings.policy/volume_policy.fidl
| Ordinal | Variant | Type | Description |
|---|---|---|---|
1 |
response |
VolumePolicyController_RemovePolicy_Response
|
|
2 |
err |
Error
|
ALIASES
| Name | Value | Description |
|---|---|---|
| PolicyId |
uint32 |