Specifies whether the decoder should perform Lt-Rt fold down.

Constant for IPropertyBag

Available only by using IPropertyStore.

Data Type


Default Value



If this property has a value of VARIANT_FALSE and the output is stereo, the audio decoder uses simple channel fold down. If this property has a value of VARIANT_TRUE, the audio decoder performs Lt-Rt (matrixed) fold down to stereo, and then any Dolby Surround decoder can be used to decode the matrixed surround . For example, the audio decoder could perform Lt-Rt fold down on 5.1 or 7.1 content.

This property is supported only when the decoder is acting as a DirectX Media Object (DMO). No fold down of any kind is supported when the decoder is acting as a Media Foundation Transform (MFT).

On Windows Vista, if you obtain an IPropertyStore interface on an audio decoder, the decoder acts as an MFT. Consequently, this property cannot be used on Windows Vista. For information on when a decoder acts as a DMO or an MFT, see the individual codec reference pages under Codec Objects.


Minimum supported client
Windows XP [desktop apps only]
Minimum supported server
Windows Server 2003 [desktop apps only]

See also

Media Foundation Properties