Sets a preferred media source handler's GUID.


#include "ltmf.h"

Language Syntax
C HRESULT IltmfPlay_SetPreferredMediaSourceHandler(pPlay, MediaSourceHandlerType, Val)
C++ HRESULT SetPreferredMediaSourceHandler(MediaSourceHandlerType, Val)


IltmfPlay *pPlay

Pointer to an IltmfPlay interface.

long MediaSourceHandlerType

Value that indicates the desired media source handler type. For a list of possible values, refer to ltmfPlay_PreferredMediaSourceHandler constants.


String that has the following possible values:

For a list of possible values, refer to ltmfMediaSourceHandler constants.


Value Meaning
S_OK The function was successful.
<> S_OK An error occurred. Refer to the Error Codes or the HRESULT error codes in the MediaFoundation documentation.


By default, the toolkit creates media sources according to the default Media Foundation mechanism, and thats by using a Source Resolver which is standard way to create media sources. However, sometimes 3rd party media sources get installed on some computers and assigns their media source handler to a specific media type and are used instead of the media sources you shipped with your application. And unexpected problems can occur if these media sources are not working properly. This function allows you to control which media sources are used in your application. You can decide to use a certain media source handler or you can choose to use only the LEAD ones.

Val is a string for the GUID of the media source handler. This GUID uniquely identifies the media source handler. Every media format has a registered media source handler(s) who are responsible of creating a media source for this media type.

For example, the GUID for the LEAD MPEG2 Transport Media Source Handler is:


If the MediaSourceHandlerType argument is equal to ltmfConvert_PreferredMediaSourceHandler_Generic, then the possible values for Val are: ltmfMediaSourceHandler_LEADDefault or ltmfMediaSourceHandler_DontCare.

If ltmfMediaSourceHandler_LEADDefault is specified, then the LEAD default media source handlers will be set for ALL of the values listed in ltmfPlay_PreferredMediaSourceHandler.

If ltmfMediaSourceHandler_DontCare is specified, then the internal list of the preferred media source handlers will be cleared and the media source will be created using the Media Foundation's default mechanism (Source Resolver).

Use the ltmfMediaSourceHandler_XXX constants whenever possible. See ltmfMediaSourceHandler constants for a list of predefined values.

Required DLLs and Libraries


Win32, x64.

See Also




For a C++ example, refer to IltmfPlay::SetPreferredMediaSourceHandler Example for C++.

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© 1991-2023 LEAD Technologies, Inc. All Rights Reserved.