files/en-us/web/api/mediatracksettings/latency/index.md
{{APIRef("Media Capture and Streams")}}
The {{domxref("MediaTrackSettings")}} dictionary's
latency property is a double-precision floating-point
number indicating the estimated latency (specified in seconds) of the
{{domxref("MediaStreamTrack")}} as currently configured. This lets you determine what
value was selected to comply with your specified constraints for this property's value
as described in the {{domxref("MediaTrackConstraints.latency")}} property you provided
when calling either {{domxref("MediaDevices.getUserMedia", "getUserMedia()")}} or
{{domxref("MediaStreamTrack.applyConstraints()")}}.
This is, of course, an approximation, since latency can vary for many reasons including CPU, transmission, and storage overhead.
If needed, you can determine whether or not this constraint is supported by checking the value of {{domxref("MediaTrackSupportedConstraints.latency")}} as returned by a call to {{domxref("MediaDevices.getSupportedConstraints()")}}. However, typically this is unnecessary since browsers will ignore any constraints they're unfamiliar with.
Because {{Glossary("RTP")}} doesn't include this information, tracks associated with a WebRTC {{domxref("RTCPeerConnection")}} will never include this property.
A double-precision floating-point number indicating the estimated latency, in seconds, of the audio track as currently configured.
See the Constraint exerciser example.
{{Specifications}}
{{Compat}}