Debugging DirectShow Filter

I'm developing a DirectShow filter that it's input connects to H.264 encoder's output, the filter purpose is to insert FEC bits just before the H.264 NAL's header, what requires me to read the encoder's data on the bit LEVEL.

I alre开发者_运维百科ady made the FEC filter DLL and connected it using GraphEdit. Suppose I want to see some LOG msg with the video data(bits) entering my filter in the GraphEdit anyone knows how to generate those log msgs or log file?

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there're two possibilities:

1) implement logging of anything you need to know to external file in you FEC filter

2) you can put "smart tee" filter before (and/or after) your FEC filter to "tee" the stream and connect the second pin to "dump" filter (http://msdn.microsoft.com/en-us/library/dd388553(v=vs.85).aspx) that can write all received samples to the file for later analysis

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OutputDebugString and attaching a debugger will print the messages into the debug window of the IDE.

On the other hand, you can use output logger like DbgView which capture all OutputDebugString messages in the system.

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Some tools for analyzing data flow between filters:

Open source graph editor GraphStudioNext analyzer filter (and analyzer file writer) will show you a visual log of activity when inserted between two filters of interest. You'll need to build it yourself to get this feature for now.

Geraint Davie's monitor filter will write a log file of activity to disk.

See this question: How to debug c++ DirectShow filter for further techniques