Log Object

An object for logging parameters of DirectShow graphs, filters, streams and messages from applications/libraries.


The Log object is great tool for debugging your DirectShow application.


The log object writes to the file:
  • Computer and OS Windows settings.
  • Host application and loaded DLL parameters.
  • Messages from filters, DLLs and application.
Third party applications can use the OutputDebugStringA() and OutputDebugStringW() methods to write to a log file.


To prepare files with the studied features and properties, do the following:

1. Download Log Object and unzip log_object..zip to some catalog.

2. Run register.bat. Please, set check box in "Make this copy..." - shown on Log_register.gif. Also - don't forget name of selected catalog for save log file.

3. Register a debug version of the AVObject filter you are checking, or download and install Spy Filter.

3. Run your application or graph (the Debug version of the AVObject filter or the Spy filter must be included in the graph).

4. Zip the log file and send it to us or upload to our FTP.


  • Only debug version of our filters will write the log file. Please make sure a debug version is registered.
  • Please remember to unregister the log object after use. Log files can be VERY large (up to hundreds of GB) if the option “Add new log to the end of the old file” is selected (default option).

You can find the path to the 32-bit log object in the following registry key:


and to the 64-bit:


These keys have subkeys with paths to log32.dll and log64.dll. Also, these subkeys have a "Log" parameter with the value: path to the log file and other parameters.

Related Products

  • 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.
  • 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).

See Also

Action Items