IAsyncReader Interface (Compact 2013)

3/26/2014

This interface allows multiple overlapped reads from different positions in the media stream. This interface is supported by source filters.

Note that during connection an output pin supporting the IAsyncReader should check whether its QueryInterface method is called asking for the IAsyncReader interface. If it is not, then the output pin should fail the connect unless it establishes some other transport to use during the connection.

When to Implement

Implement this interface on a pin if your filter reads data of media type MEDIATYPE_Stream from some source.

When to Use

A parser, such as a WAVE parser filter, can use this interface to read from a filter that reads from a file, the network, or memory.

Methods in Vtable Order

The following table shows the methods that appear in the Vtable beneath the standard COM methods inherited from IUnknown.

Method	Description
RequestAllocator	Retrieves the actual allocator to be used.
Request	Queues a request for data.
WaitForNext	Blocks until the next sample is completed or the time-out occurs.
SyncReadAligned	Performs an aligned synchronized read.
SyncRead	Performs a synchronized read.
Length	Retrieves the total length of the stream, and the currently available length.
BeginFlush	Causes all outstanding reads to return.
EndFlush	Ends the flushing operation.

Requirements

Header	dshow.h
Library	Strmiids.lib

See Also

Reference

DirectShow Interfaces