The ReadFormat method obtains format information from a stream. Fills and returns a structure with the data in an application-defined buffer. If no buffer is supplied, determines the buffer size needed to retrieve the buffer of format data. Called when an application uses the AVIStreamReadFormat function.
HRESULT ReadFormat(
PAVISTREAM ps,
LONG lPos,
LPVOID lpFormat,
LONG *lpcbFormat
);
Returns the HRESULT defined by OLE.
The type of data stored in a stream dictates the format information and the structure that contains the format information. A stream handler should return all applicable format information in this structure, including palette information when the format uses a palette. A stream handler should not return stream data with the structure.
Standard video stream handlers provide format information in a BITMAPINFOHEADER structure. Standard audio stream handlers provide format information in a PCMWAVEFORMAT structure. Other data streams can use other structures that describe the stream data.
For handlers written in C++, ReadFormat has the following syntax:
HRESULT ReadFormat(LONG lPos, LPVOID lpFormat,
LONG *lpcbFormat)
Windows NT: Requires version 3.1 or later.
Windows: Requires Windows 95 or later.
Windows CE: Unsupported.
Header: Declared in vfw.h.
Import Library: Use vfw32.lib.
Custom File and Stream Handlers Overview, Custom File and Stream Handler Interfaces, AVIStreamReadFormat, BITMAPINFOHEADER, PCMWAVEFORMAT