fmod_wav_out

Simple fmod output plugin which allows writing to custom files to do synced offline rendering for trailer videos etc.

Build

• fmod headers need to go in the ./fmod folder (like ./fmod/fmod.hpp etc.).
• fmod binaries need to in ./lib (like ./lib/libfmod.so, ./lib/fmod_vc.lib)
• mkdir build
• cd build
• cmake ..
• cmake --build . or open .sln

Usage

• This plugin is not intended to be loaded via FMOD::System::loadPlugin()! (Easy to change though)
• Call fmod_wav_out_register(FMOD::System* system) with the fmod system instance.
  • Will register the output plugin to fmod
  • Change the fmod block size FMOD::System::setDSPBufferSize to ensure each update produces the exact amount of audio samples needed for the (hardcoded) framerate fmod_wav_out_fps
  • Will return a output plugin handle on success.
• Call FMOD::System::setOutputByPlugin with the handle returned above.
  • I haven't changed the output after FMOD:Studio.init, there might be some problems.
• Call FMOD::System.init or FMOD:Studio.init with theses flags to ensure everything runs properly in non realtime.
  • FMOD::System
    • FMOD_INIT_MIX_FROM_UPDATE each FMOD::System.update call will directly call fmod_wav_upate
    • FMOD_INIT_STREAM_FROM_UPDATE otherwise streaming samples might run out when rendering at high frame rates.
    • FMOD_INIT_THREAD_UNSAFE optional, but the init flags above get rid of any threading.
  • FMOD::Studio not tested, but these should probably be set when using Studio.
    • FMOD_STUDIO_INIT_SYNCHRONOUS_UPDATE
    • FMOD_STUDIO_INIT_LOAD_FROM_UPDATE
• Get the internal plugin state handle after fmod is initialized with FMOD::System.getOutputHandle.
  • Not to be confused with the handle returned from fmod_wav_out_register
  • This handle only points to the correct data after FMOD::System::setOutputByPlugin was called!
  • It points to fmod_wav_out_state and this state is needed for the other functions below.
• fmod_wav_out_prepare_recording(fmod_wav_out_state* state, const char* path) Opens the file handle to the provided path (e.g. /tmp/output.wav)
• fmod_wav_out_start_recording(fmod_wav_out_state* state) will start writing audio to the prepared output file on the next FMOD::System.update or FMOD::Studio.update call.
• Keep calling FMOD::System.update or FMOD::Studio.update
• fmod_wav_out_stop_recording(fmod_wav_out_state* state) stops recording and closes the output file.
• Repeat if needed.

P/Invoke for c#

[DllImport("fmod_wav_out", CallingConvention = CallingConvention.Cdecl)]
public static extern uint fmod_wav_out_register(IntPtr systemHandle);

[DllImport("fmod_wav_out", CallingConvention = CallingConvention.Cdecl)]
public static extern bool fmod_wav_out_stop_recording(IntPtr pluginHandle);

[DllImport("fmod_wav_out", CallingConvention = CallingConvention.Cdecl)]
public static extern bool fmod_wav_out_prepare_recording(IntPtr pluginHandle, IntPtr path);

[DllImport("fmod_wav_out", CallingConvention = CallingConvention.Cdecl)]
public static extern bool fmod_wav_out_start_recording(IntPtr pluginHandle);