IMFRateControl::SetRate method (mfidl.h)

Article
07/27/2022

Sets the playback rate.

Syntax

HRESULT SetRate(
  [in] BOOL  fThin,
  [in] float flRate
);

Parameters

[in] fThin

If TRUE, the media streams are thinned. Otherwise, the stream is not thinned. For media sources and demultiplexers, the object must thin the streams when this parameter is TRUE. For downstream transforms, such as decoders and multiplexers, this parameter is informative; it notifies the object that the input streams are thinned. For information, see About Rate Control.

[in] flRate

The requested playback rate. Positive values indicate forward playback, negative values indicate reverse playback, and zero indicates scrubbing (the source delivers a single frame).

Return value

The method returns an HRESULT. Possible values include, but are not limited to, those in the following table.

Return code	Description
S_OK	The method succeeded.
MF_E_REVERSE_UNSUPPORTED	The object does not support reverse playback.
MF_E_THINNING_UNSUPPORTED	The object does not support thinning.
MF_E_UNSUPPORTED_RATE	The object does not support the requested playback rate.
MF_E_UNSUPPORTED_RATE_TRANSITION	The object cannot change to the new rate while in the running state.

Remarks

The Media Session prevents some transitions between rate boundaries, depending on the current playback state:

Playback State	Forward/Reverse	Forward/Zero	Reverse/Zero
Running	No	No	No
Paused	No	Yes	No
Stopped	Yes	Yes	Yes

If the transition is not supported, the method returns MF_E_UNSUPPORTED_RATE_TRANSITION.

When a media source completes a call to SetRate, it sends the MESourceRateChanged event. Other pipeline components do not send this event.

If a media source switches between thinned and non-thinned playback, the streams send an MEStreamThinMode event to indicate the transition. Events from the media source are not synchronized with events from the media streams. After you receive the MESourceRateChanged event, you can still receive samples that were queued before the stream switched to thinned or non-thinned mode. The MEStreamThinMode event marks the exact point in the stream where the transition occurs.

When the Media Session completes a call to SetRate, it sends the MESessionRateChanged event.

Requirements

Requirement	Value
Minimum supported client	Windows Vista [desktop apps \| UWP apps]
Minimum supported server	Windows Server 2008 [desktop apps \| UWP apps]
Target Platform	Windows
Header	mfidl.h
Library	Mfuuid.lib