MediaTrackControls.volume - Web APIs 编辑

Obsolete

This feature is obsolete. Although it may still work in some browsers, its use is discouraged since it could be removed at any time. Try to avoid using it.

The MediaTrackConstraints dictionary's volume property is a ConstrainDouble describing the requested or mandatory constraints placed upon the value of the volume constrainable property.

If needed, you can determine whether or not this constraint is supported by checking the value of MediaTrackSupportedConstraints.volume as returned by a call to MediaDevices.getSupportedConstraints(). However, typically this is unnecessary since browsers will ignore any constraints they're unfamiliar with.

Syntax

var constraintsObject = { volume: constraint };

constraintsObject.volume = constraint;

Value

A ConstrainDouble describing the acceptable or required value(s) for an audio track's volume, on a linear scale where 0.0 means silence and 1.0 is the highest supported volume.

If this value is a number, the user agent will attempt to obtain media whose volume is as close as possible to this number given the capabilities of the hardware and the other constraints specified. Otherwise, the value of this ConstrainDouble will guide the user agent in its efforts to provide an exact match to the required volume (if exact is specified or both min and max are provided and have the same value) or to a best-possible value.

Any constraint set which only permits values outside the range 0.0 to 1.0 cannot be satisfied and will result in failure.

Example

See Example: Constraint exerciser in Capabilities, constraints, and settings for an example.

Browser compatibility

BCD tables only load in the browser

See also

• Media Capture and Streams API
• Capabilities, constraints, and settings
• MediaTrackConstraints
• MediaDevices.getSupportedConstraints()
• MediaTrackSupportedConstraints
• MediaStreamTrack