IAVIStream::Read method

The Read method reads data from a stream and copies it to an application-defined buffer. If no buffer is supplied, it determines the buffer size needed to retrieve the next buffer of data. Called when an application uses the AVIStreamRead function.

Syntax


HRESULT Read(
   PAVISTREAM ps,
   LONG       lStart,
   LONG       lSamples,
   LPVOID     lpBuffer,
   LONG       cbBuffer,
   LONG       *plBytes,
   LONG       *plSamples
);

Parameters

ps

Pointer to the interface to a stream.

lStart

Starting sample or frame number to read.

lSamples

Number of samples to read.

lpBuffer

Pointer to the application-defined buffer to contain the stream data. You can also specify NULL to request the required size of the buffer. Many applications precede each read operation with a query for the buffer size to see how large a buffer is needed.

cbBuffer

Size, in bytes, of the buffer specified by lpBuffer.

plBytes

Pointer to a buffer that receives the number of bytes read.

plSamples

Pointer to a buffer that receives the number of samples read.

Return value

Returns AVIERR_OK if successful or AVIERR_BUFFERTOOSMALL if the buffer is not large enough to hold the data. If successful, Read also returns either a buffer of data with the number of frames (samples) included in the buffer or the required buffer size, in bytes.

Remarks

For handlers written in C++, Read has the following syntax:



HRESULT Read(LONG lStart, LONG lSamples, 
    LPVOID lpBuffer, LONG cbBuffer, 
    LONG *plBytes, LONG *plSamples); 
 


Requirements

Minimum supported client

Windows 2000 Professional [desktop apps only]

Minimum supported server

Windows 2000 Server [desktop apps only]

Header

Vfw.h

Library

Vfw32.lib

See also

Custom File and Stream Handlers
Custom File and Stream Handler Interfaces

 

 

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