WM ASF Writer Filter
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4/8/2010
The WM ASF Writer is a wrapper filter for a file writer object for Windows Media formats. The filter accepts a variable number of input streams and creates an Advanced Systems Format (ASF) file. The filter handles all compression and multiplexing (although the compression mechanism can be bypassed). You can use the WM ASF Writer in various scenarios including digital video (DV) capture, audio recompression, and conversion of Audio-Video Interleaved (AVI). This filter provides the only way to create Microsoft® Windows Media™ Audio and Windows Media Video files in Microsoft DirectShow.
For more information, see Creating ASF Files in DirectShow.
The following table shows the filter properties.
| Fliter Property | Description |
|---|---|
Filter Interfaces |
IAMFilterMiscFlags, IBaseFilter, IFileSinkFilter2, IMediaSeeking, IPersistStream |
Input Pin Media Types |
Depends on the ASF profile. Typically uncompressed audio and video types, although the filter will accept compressed types if they match the ASF profile. |
Input Pin Interfaces |
|
Output Pin Media Types |
Not applicable. |
Output Pin Interfaces |
Not applicable. |
Filter CLSID |
CLSID_WMAsfWriter |
Property Page CLSID |
CLSID_AsfWriterProperties |
Executable |
Qasf.dll |
MERIT_DO_NOT_USE |
|
Not specified |
Remarks
The filter requires the Windows Media Format Software Development Kit (SDK) and its underlying dependencies.
The number of input pins on the filter dependings on the profile or profile identifier of the ASF stream.
The input pins support one method from the IAMStreamConfig interface: IAMStreamConfig::GetFormat. All other methods return E_NOTIMPL. Call the GetFormat method to query the pin's destination compression format, which is defined by the current ASF profile.