Spy Filter

DirectShow filter for tracing (together with the log object) connections, positioning, data flow, etc, to save input Direct Show samples to file(s).


Spy Filter is a great tool for debugging DirectShow application and interaction between filters.


Writes to the log file (with Log Object):
  • Connection media type, allocator properties, list of media types from the upstream filter
  • Graph structure
  • Input DirectShow samples
  • Seeking (IMediaSeeking), flushing, NewSegment, EndOfStream, etc.
Saves input DirectShow samples:
  • As a binary file(s), with the connection media type at the beginning of the file (binary and text formats) and one or more samples in the file.
  • As compressed binary file(s), with the connection media type at the beginning and a set of repeating 16-byte sequences. This type is very useful for saving VANC data.
  • As RGB or YUV bitmap (.bmp) file(s). BITMAPINFOHEADER from the connection media type is written to the bitmap file as is. The input data is also saved to a file without color space conversion to RGB. Accordingly, not all saved files can be viewed in MS Paint or other programs.
Specifications and description of user interfaces can be found in the .idl file in the \Idl folder of the filter installation directory.


To check various properties of video, audio, and other streams, do the following:

1. Download and install Spy Filter.

2. Download and install Log Object.

3. Insert Spy filter into the DirectShow graph between the filters of interest (connect the input and output pins).

4. Run, stop and close DirectShow graph.

5. Check the log file created by Spy filter with the Log object.

Related Products

  • Log Object - Log object for logging the parameters of the DS graph.
  • Video Generator - DirectShow filter for generating a video stream with the necessary parameters, for creating video frames for checking chroma key, for outputting an audio stream synchronized with video, and much more.

See Also

Action Items