IMFSourceReader::GetPresentationAttribute method

Gets an attribute from the underlying media source.

Syntax

HRESULT GetPresentationAttribute(
  [in]  DWORD       dwStreamIndex,
  [in]  REFGUID     guidAttribute,
  [out] PROPVARIANT *pvarAttribute
);

Parameters

dwStreamIndex [in]

The stream or object to query. The value can be any of the following.

Value	Meaning
0–0xFFFFFFFB	The zero-based index of a stream.
MF_SOURCE_READER_FIRST_VIDEO_STREAM 0xFFFFFFFC	The first video stream.
MF_SOURCE_READER_FIRST_AUDIO_STREAM 0xFFFFFFFD	The first audio stream.
MF_SOURCE_READER_MEDIASOURCE 0xFFFFFFFF	The media source.

 

guidAttribute [in]

A GUID that identifies the attribute to retrieve. If the dwStreamIndex parameter equals MF_SOURCE_READER_MEDIASOURCE, guidAttribute can specify one of the following:

• A presentation descriptor attribute. For a list of values, see Presentation Descriptor Attributes.
• MF_SOURCE_READER_MEDIASOURCE_CHARACTERISTICS. Use this value to get characteristics flags from the media source.

Otherwise, if the dwStreamIndex parameter specifies a stream, guidAttribute specifies a stream descriptor attribute. For a list of values, see Stream Descriptor Attributes.

pvarAttribute [out]

A pointer to a PROPVARIANT that receives the value of the attribute. Call the PropVariantClear function to free the PROPVARIANT.

Return value

If this method succeeds, it returns S_OK. Otherwise, it returns an HRESULT error code.

Remarks

This interface is available on Windows Vista if Platform Update Supplement for Windows Vista is installed.

Requirements

See also

Media Foundation Attributes

Source Reader

IMFSourceReader