files/en-us/web/api/mediatrackconstraints/autogaincontrol/index.md
{{APIRef("Media Capture and Streams")}}
The {{domxref("MediaTrackConstraints")}} dictionary's autoGainControl property is a ConstrainBoolean describing the requested or mandatory constraints placed
upon the value of the {{domxref("MediaTrackSettings.autoGainControl", "autoGainControl")}} constrainable property.
If needed, you can determine whether or not this constraint is supported by checking the value of {{domxref("MediaTrackSupportedConstraints.autoGainControl")}} as returned by a call to {{domxref("MediaDevices.getSupportedConstraints()")}}. However, typically this is unnecessary since browsers will ignore any constraints they're unfamiliar with.
Automatic gain control is typically a feature provided by microphones, although it can be provided by other input sources as well.
If this value is a simple true or false, the user agent will
attempt to obtain media with automatic gain control enabled or disabled as specified, if
possible, but will not fail if this can't be done. If, instead, the value is given as an
object with an exact field, that field's Boolean value indicates a required
setting for the automatic gain control feature; if it can't be met, then the request
will result in an error.
See the Constraint exerciser example.
{{Specifications}}
{{Compat}}