MediaTrackSupportedConstraints.frameRate
The MediaTrackSupportedConstraints
dictionary's
frameRate
property is a read-only Boolean value which is
present (and set to true
) in the object returned by
MediaDevices.getSupportedConstraints()
if and only if the
user agent supports the frameRate
constraint.
If the constraint isn't supported, it's not included
in the list, so this value will never be false
.
The frameRate
constraint can be used to establish acceptable upper and
lower bounds on the video frame rate for a new video track, or to specify an exact frame
rate that must be provided for the request to succeed. Checking the value of this
property lets you determine if the user agent allows constraining the video track
configuration by frame rate. See the example to see how this can
be used.
Value
This property is present in the dictionary if the user agent supports the
frameRate
constraint. If the property isn't present, the user agent doesn't
allow specifying limits on the frame rate for video tracks.
Note: If this property is present, its value is always true
.
Examples
This simple example looks to see if your browser supports constraining the frame rate when requesting video tracks.
JavaScript
let result = document.getElementById("result");
if (navigator.mediaDevices.getSupportedConstraints().frameRate) {
result.textContent = "Supported!";
} else {
result.textContent = "Not supported!";
}
HTML
<div id="result">
</div>
CSS
#result {
font: 14px "Arial", sans-serif;
}
Result
The output, showing if your browser supports the frameRate
constraint, is:
While this example is trivial, you can replace the simple output of "Supported" vs. "Not supported" with code to provide alternative methods for presenting the audiovisual information you want to share with the user or otherwise work with.
Specifications
Specification |
---|
Media Capture and Streams # dom-mediatracksupportedconstraints-framerate |
Browser compatibility
BCD tables only load in the browser