IAVIStream::Read method (vfw.h)

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

Parameters

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

See also

Custom File and Stream Handler Interfaces

Custom File and Stream Handlers