通过

CSourceStream::GetMediaType

  • 项目
 
Microsoft DirectShow 9.0

CSourceStream::GetMediaType

The GetMediaType method retrieves a preferred media type.

Syntax

  virtual HRESULT GetMediaType(
    int iPosition,
    CMediaType *pMediaType
);

virtual HRESULT GetMediaType(
    CMediaType *pMediaType
);

Parameters

iPosition

Zero-based index value.

pMediaType

Pointer to a CMediaType object that receives the media type.

Return Value

Returns one of the HRESULT values shown in the following table.

Value Description
S_OK Success.
VFW_S_NO_MORE_ITEMS Index out of range.
E_INVALIDARG Index less than zero.
E_UNEXPECTED Unexpected error.

Remarks

There are two versions of this method. One version overrides the CBasePin::GetMediaType method and takes an index value as a parameter. The other version is designed to retrieve a single media type, so it lacks the index parameter.

The single-parameter method returns E_UNEXPECTED. The two-parameter method verifies that the iPosition parameter is zero and then calls the single-parameter version. Depending on the number of media types the pin supports, you must override one of these methods:

  • If the pin supports exactly one media type, override the single-parameter version. Fill in the media type that the pin supports.
  • If the pin supports more than one media type, override the two-parameter version. Also override the CSourceStream::CheckMediaType method.

Requirements

**  Header:** Declared in Source.h; include Streams.h.

**  Library:** Use Strmbase.lib (retail builds) or Strmbasd.lib (debug builds).

See Also