MediaTrackConstraints.channelCount - Web APIs 编辑

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

If needed, you can determine whether or not this constraint is supported by checking the value of MediaTrackSupportedConstraints.channelCount 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 = { channelCount: constraint };

constraintsObject.channelCount = constraint;

Value

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

The channel count is 1 for monaural sound, 2 for stereo, and so forth.

Example

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

Specifications

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