Easiest way to use speex preprocessor in C#?

Question

I need to use the speex preprocessor, and only the preprocessor in my VOIP app (don't need to use the codec). My app is written in C#. I think I know the easiest steps, but not sure where to find these items.

Easiest in my opinion, if I can find these:

1. Windows DLL that contains only the preprocessor functions, or if small enough in size I guess the entire speex library would be OK. So far I've only found binarys in EXE format, so if I can't find the binaries I'd have to install the compiler they use to build their source and probably several other libraries (as is my experience with most open source builds).

2. C# versions of the header files, for pinvoking the DLL functions.

So my question is, does anyone know where I can find these? I'm sure people have created these before, based on the huge number of speex users, just not able to find any on-line.

Hope people don't think I'm lazy, I just hate doing this kind of "busy work" if I know many others have probably already done the exact same thing :)

Update: I did find http://www.rarewares.org/files/others/libspeex-dll-1.2rc1.zip which includes libspeex.dll, but the DLL has no exports so not sure how they expect that to work. The other binaries they have are also just EXEs.

Answer 1

I only ended up using a few functions, but incase anyone doesn't want to do the work, here is what I wrote:

    [DllImportAttribute("libspeexdsp.dll")]
    public static extern IntPtr speex_echo_state_init(int frameSize,int filterLength);

    [DllImportAttribute("libspeexdsp.dll")]
    public static extern void speex_echo_state_destroy(IntPtr st);

    [DllImportAttribute("libspeexdsp.dll")]
    public static extern void speex_echo_cancellation(IntPtr st, IntPtr recorded, IntPtr played, IntPtr echoRemoved);

    [DllImportAttribute("libspeexdsp.dll")]
    public static extern void speex_echo_playback(IntPtr st, IntPtr played);

    [DllImportAttribute("libspeexdsp.dll")]
    public static extern void speex_echo_capture(IntPtr st, IntPtr recorded, IntPtr echoRemoved);

    [DllImportAttribute("libspeexdsp.dll")]
    public unsafe static extern int speex_echo_ctl(IntPtr st, int id, ref IntPtr val);

    [DllImportAttribute("libspeexdsp.dll")]
    public static extern IntPtr speex_preprocess_state_init(int frameSize, int sampleRate);

    [DllImportAttribute("libspeexdsp.dll")]
    public static extern int speex_preprocess_ctl(IntPtr st, int id, IntPtr val);

    [DllImportAttribute("libspeexdsp.dll")]
    public static extern int speex_preprocess_run(IntPtr st, IntPtr recorded);

    [DllImportAttribute("libspeexdsp.dll")]
    public static extern void speex_preprocess_state_destroy(IntPtr st);

I guess I was lucky in that there were not a lot of structures to delcare, mostly everything is IntPtr or int, so pretty easy.

As far as finding the binaries, I didn't find them precompiled anywhere, but the source did include VS solution files that compiled with only a couple of minor changes, so I guess that part is easy enough for anyone using C#, since they'll be using VS anyway. For some reason I had assumed it would require some other compiler, like GCC, or others that most open source projects seem to use (none of which I'm familiar with). Again, luckily, it didn't!

Answer 2

Speex is written and C, and it has exports. I just downloaded the source code myself and looked. Download the source here, and go from there http://www.speex.org/downloads/. It looks to be quite extensive, ... happy coding.

Of course, there is this, but it is still in beta:

http://nspeex.codeplex.com/