WM ASF Reader Filter

The WM ASF Reader is a wrapper filter for the reader object provided with the Microsoft Windows Media™ Format SDK and is the recommended source filter for file playback of Windows Media-based content and content created with any of the Microsoft MPEG-4 Encoder DMOs. In DirectX 9.x and DirectX 8.x, this filter is never used by IGraphBuilder::RenderFile. It must be explicitly added to a filter graph using its CLSID.

Note   The most recent version of this filter will become available in the Windows Media Format 9 Series SDK. The new version of the WM ASF Reader is the default source filter for Windows Media-based content and it is used by RenderFile.

In general, this version of the WM ASF Reader is the one that applications should use to play ASF content, including Windows Media Audio and Windows Media Video as well as MPEG-4 content authored with the Microsoft MPEG-4 Encoder. Seeking performance is much better than with the Windows Media Source Filter. However, only ASF files that have been authored with an index are seekable.

When given the name of an ASF file or a URL, the WM ASF Reader reads the compressed content, parses the compressed streams, and exposes an output pin for each one. This filter connects downstream to audio and/or video codecs filters, which do the decompression. Seeking is supported if the ASF file is seekable. The ASF Reader time stamps the samples before sending them downstream, but it does not modify the time stamps in any way.

To use this filter you must install the Microsoft® Windows Media™ Format (SDK).

See Also

• Reading ASF Files in DirectShow
• Windows Media Source Filter