File Writer Filter

[The feature associated with this page, DirectShow, is a legacy feature. It has been superseded by MediaPlayer, IMFMediaEngine, and Audio/Video Capture in Media Foundation. Those features have been optimized for Windows 10 and Windows 11. Microsoft strongly recommends that new code use MediaPlayer, IMFMediaEngine and Audio/Video Capture in Media Foundation instead of DirectShow, when possible. Microsoft suggests that existing code that uses the legacy APIs be rewritten to use the new APIs if possible.]

The File Writer filter can be used to write files to disc regardless of format. The filter simply writes to disc whatever it receives on its input pin, so it must be connected upstream to a multiplexer that can format the file correctly. You can create a new output file with the File Writer or specify an existing file; if the file already exists, it will be completely overwritten with the new data.

The file writer filter uses the input stream's time stamps as file offsets and provides random access to the file. It supports IStream to allow reading and writing the file header after the graph is stopped. To improve performance it also supports unbuffered overlapped writes and handles the corresponding buffer negotiation.


To write ASF files, use the WM ASF Writer filter.


Label Value
Filter Interfaces IAMFilterMiscFlags, IBaseFilter, IFileSinkFilter, IFileSinkFilter2, IPersistStream
Input Pin Interfaces IMemInputPin, IPin, IQualityControl, IStream
Output Pin Media Types Not applicable
Output Pin Interfaces Not applicable
Filter CLSID CLSID_FileWriter
Property Page CLSID No property page
Executable qcap.dll
Filter Category CLSID_LegacyAmFilterCategory


DirectShow Filters