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The IEnumMediaTypesinterface enumerates the preferred formats for a pin.
When to Implement
This interface must be implemented and made available by the IPin::EnumMediaTypesmethod. The CBasePin::EnumMediaTypesmember function automatically does this in the Microsoft DirectShow class library and uses the CEnumMediaTypesclass to create the enumerator object.
When to Use
This interface is normally used by a connecting pin to determine the media type when negotiating a connection. It can also be passed through to other pins, either upstream or downstream of the filter, when intervening filters do not have a list of preferred media types. For example, a transform-inplace filter might pass the IEnumMediaTypesinterface of a downstream input pin to the connecting output pin of the upstream filter, instead of providing its own IEnumMediaTypesinterface.
Methods in Vtable Order
| IUnknown methods | Description |
|---|---|
| QueryInterface | Returns pointers to supported interfaces. |
| AddRef | Increments the reference count. |
| Release | Decrements the reference count. |
| IEnumMediaTypes methods | Description |
| Next | Retrieves the specified number of items in the enumeration sequence. |
| Skip | Skips a specified number of elements in the enumeration sequence. |
| Reset | Resets the enumeration sequence to the beginning. |
| Clone | Returns another enumerator containing the same enumeration state as the current one. |