files/en-us/web/api/mediatrackconstraints/samplerate/index.md
{{APIRef("Media Capture and Streams")}}
The {{domxref("MediaTrackConstraints")}} dictionary's
sampleRate property is a ConstrainULong
describing the requested or mandatory constraints placed upon the value of the
{{domxref("MediaTrackSettings.sampleRate", "sampleRate")}} constrainable property.
If needed, you can determine whether or not this constraint is supported by checking the value of {{domxref("MediaTrackSupportedConstraints.sampleRate")}} as returned by a call to {{domxref("MediaDevices.getSupportedConstraints()")}}. However, typically this is unnecessary since browsers will ignore any constraints they're unfamiliar with.
If this value is a number, the user agent will attempt to obtain media whose sample
rate is as close as possible to this number given the capabilities of the hardware and
the other constraints specified. Otherwise, the value of this
ConstrainULong will guide the user agent in its efforts to provide an
exact match to the required sample rate (if exact is specified or both
min and max are provided and have the same value) or to a
best-possible value.
See the Constraint exerciser example.
{{Specifications}}
{{Compat}}