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IWMHeaderInfo3::ModifyAttribute method

The ModifyAttribute method modifies the settings of an existing attribute.

Syntax


HRESULT ModifyAttribute(
  [in]  WORD wStreamNum,
  [in]  WORD wIndex,
  [in]  WMT_ATTR_DATATYPE Type,
  [in]  WORD wLangIndex,
  [in]  const BYTE *pValue,
  [in]  DWORD dwLength
);

Parameters

wStreamNum [in]

WORD containing the stream number to which the attribute applies. Pass zero for file-level attributes.

wIndex [in]

WORD containing the index of the attribute to change.

Type [in]

Type of data used for the new attribute value. For more information about the types of data supported, see WMT_ATTR_DATATYPE.

wLangIndex [in]

WORD containing the language index of the language to be associated with the new attribute. This is the index of the language in the language list for the file.

pValue [in]

Pointer to an array of bytes containing the attribute value.

dwLength [in]

DWORD containing the length of the attribute value, in bytes.

Return value

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

Return codeDescription
S_OK

The method succeeded.

E_INVALIDARG

An illegal parameter combination, data type, or attribute name was used.

E_NOTIMPL

The method is not implemented on a reader object.

E_POINTER

A pointer is not valid.

NS_E_ATTRIBUTE_READ_ONLY

The attribute cannot be changed.

NS_E_INVALID_REQUEST

wStreamNum is not a valid stream number, or there is no attribute at wIndex.

 

Remarks

You can use 0xFFFF for the stream number to specify an attribute using its global index. Global index values range from 0 to one less than the count of attributes received from a call to IWMHeaderInfo3::GetAttributeCountEx where the stream number was set to 0xFFFF.

When setting attributes for MP3 files, the metadata editor will automatically insert a byte-order mark in accordance with the Unicode specification. If you manually insert a byte-order mark, this method will not fail, but the value will then have two marks, which can cause problems when reading the attribute.

The objects of the Windows Media Format SDK perform type checking on some supported metadata attributes, but not all of them. You should ensure that any attributes you use are set using the data type specified in the Attributes section of this documentation. Likewise, you cannot assume that an attribute set by another application will use the correct data type.

Requirements

Minimum supported client

Windows 2000 Professional [desktop apps only]

Minimum supported server

Windows 2000 Server [desktop apps only]

Version

Windows Media Format 9 Series SDK, or later versions of the SDK

Header

Wmsdkidl.h (include Wmsdk.h)

Library

Wmvcore.lib;
WMStubDRM.lib (if you use DRM)

See also

IWMHeaderInfo3 Interface

 

 

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