Transparent DirectShow (Audio) Codec

[mailed]

Hi Guys,
 
I have played around with GraphEditPlus.  It is really a great and efficient tool with a lot of capabilities; I really like it. 
 
However, can it be applied on my task:
 
I want to develop a "Transparent Audio Filter/Codec" for DirectShow that is used before the data are modified by the subsequent Audio Filter/Codec (i.e. received unmodified from the file system).
 
The data received in this codec are cached in RAM and an algorithm (which doesn't modify the data) is applied.   The audio is then provided to the subsequent audio filter/codec that was first before the new "Transparent Audio Filter" took its place.  I want that this codec is applied to all audio formats/audio file extension. I assume that the positioning of the codec has to do with merits.  Is this correct? I assume, your tool will support me to do this. (How?)
 
However, I think I need some help from a Guru.  Could you show me how you would do this or point me in the right direction?  Maybe you can send me code (example/template) of how this feature can been realized in particular how the transparent codec can been positioned at the right position within the sequence of filters.

[Dee Mon]

I guess you need to write a trans-in-place filter:
http://msdn2.microsoft.com/en-us/library/ms783049.aspx
All you need is to take an example of such filter from SDK, modify it's Transform function (which gets the data), media type negotiation (to accept any audio or just the type you need like PCM) and CLSID.

Do you want your filter to be loaded when your own program is running or whenever a user plays some audio?
In the first case you just insert your filter between file reader and audio codec (when your program builds the graph), in the second case you just register your filter with a high merit:
http://msdn2.microsoft.com/en-us/library/ms787275.aspx