IAsyncReader Interface
The IAsyncReader 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 an Apple® QuickTime® parser filter, can use this interface to read from a filter that reads from a file, the network, or memory.
Methods in Vtable Order
| IUnknown methods | Description |
|---|---|
| QueryInterface | Retrieves pointers to supported interfaces. |
| AddRef | Increments the reference count. |
| Release | Decrements the reference count. |
| IAsyncReader methods | 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. |
Last updated on Tuesday, July 13, 2004
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