I have whipped up a quick hack based on the foo_dsp_extra plugin that is distributed with the SDK.
I have added another DSP entry similar to the Convert 5.1 to Stereo called Virtual 5.1. I have added HRTF processing to create a virtualization of the 5 surround channels. Sadly I don't have many 5.1 media files to test it. Also I would like to hear of people who have a surround system (I don't have one) and how good or bad the effect of surround is conveyed using HRTF synthesis.
To install place the foo_dsp_hrtf.dll in the components directory of f2bk.
There is also a file called hrtf.bin. Here are the coefficients of all the HRTF filters based on the Gardner and Martin measurements of the Kemar dummy at MIT. My implementation is very raw, so it will read the hrtf.bin where the working directory for foobar is. Usually it will be in the foobar2000 directory. Also I will not check if the file is available for reading or not, so make sure it is there. I hope that in the future I can improve the plugin in these matters and others. For now it has very very very (I mean VERY!!) basic functionalities.
Virtual 5.1 DSP processor will take a sound stream from a files that has a 6 channels (And preferably that abides by the 5.1 standard), process each channel by an HRTF filter and then mix it to a stereo stream. To experiment the auralization effect correctly you should listen to the audio using headphones.
This is the third delivery for the plugin. An LFE has been corrected and it has been compiled in order it won't ask for any library from VS2003.Net.
You can find the file attached to this post.
Anyway I expect some comments to improve it.