Mix Microphone , Sound and background sound to raw pcm stream

How can I implement a similar scheme?
Where can you see examples of this?

                  [MY DSP]<--[CHANNEL HEAD]<---[SOUND.MP3]  
                  [MY DSP]<--[CHANNEL HEAD]<---[MICROPHONE IN]   

[MY DSP] - setup volume for channel and callBack read for RAW PCM

You’ll need to bring a few separate examples together to achieve this. Recording and playback can be found in the “record” example. Standard MP3 / Wav playback can be found in “play_sound” / “play_stream” examples. To create the submix for all three, play these Channels on a ChannelGroup, see “channel_groups” example. Finally adding your own DSP can be seen in the “dsp_custom” example.

Thank. But I ran into the problem of creating my own DSP. fmod.cs does not contain all the descriptions of structures necessary for implementation, or they are described with private.

Also, I can never get the DSPReleaseCallback.
desc.release + = DSPReleaseCallback;

It looks like there are some incomplete parts of the C# API, I’ll log some bug reports to get those fixed. If you’re experienced with C# / C++ I suggest looking at fmod_dsp.h / fmod_common.h to translate the missing bits.