---
name: "WildMidi_InitVIO"
section: "3"
platform: "linux"
package: "wildmidi"
version: "0.5.0-1"
release: "Arch Linux 2026-11-01"
platforms: ["linux"]
url: "https://new.carta.tech/WildMidi_InitVIO"
---

# WildMidi\_InitVIO(3)

Initialize the library with file I/O callbacks

## NAME

WildMidi\_InitVIO - Initialize the library with file I/O callbacks

## LIBRARY

**libWildMidi**

## SYNOPSIS

**#include \<wildmidi\_lib.h\>**

**WildMidi\_InitVIO (struct \_WM\_VIO \**callbacks*, const char \**config\_file*, uint16\_t *rate*, uint16\_t *options*)**

## DESCRIPTION

Initializes libWildMidi in preparation for playback, and sets the function pointers for file I/O as provided by the caller.  This function only needs to be called once by the program using libWildMidi.

- *callbacks*

  Pointer to a file IO callbacks structure.  The \_WM\_VIO structure is like the following:

  ```
  struct _WM_VIO {
   /* This function should allocate a buffer which has the size
    * of the requested file plus one (size+1), fill the buffer
    * with the file content, and the second parameter with the
    * size of the file. */
      void * (* allocate_file)(const char *, uint32_t *);
   /* This function should free the memory of the given buffer */
      void   (* free_file)    (void *);
  };
  ```

- *config-file*

  The file that contains the instrument configuration for the library.

- *rate*

  The sound rate you want the the audio data output at. Rates accepted by libWildMidi are 11025 - 65000.

- *options*

  The initial options to set for the library. see below.

  - WM\_MO\_LOG\_VOLUME

    By default the library uses linear volume levels typically used in computer MIDI players. These can differ somewhat to volume levels found on some midi hardware which may use a volume curve based on decibels. This option sets the volume levels to what you'd expect on such devices.

  - WM\_MO\_ENHANCED\_RESAMPLING

    By default libWildMidi uses linear interpolation for the resampling of the sound samples. Setting this option enables the library to use a resampling method that attempts to fill in the gaps giving richer sound.

  - WM\_MO\_REVERB

    libWildMidi has an 8 reflection reverb engine. Use this option to give more depth to the output.

  - WM\_MO\_WHOLETEMPO

    Ignores the fractional or decimal part of a tempo setting. If you are having timing issues try *WM\_MO\_ROUNDTEMPO* before trying this option. This option added due to some software not supporting fractional tempos allowable in the MIDI specification.

  - WM\_MO\_ROUNDTEMPO

    Rounds the fractional or decimal part of a tempo setting. Try this option is you are having timing issues, if this fails then try *WM\_MO\_WHOLETEMPO*. This option added due to some software not supporting fractional tempos allowable in the MIDI specification.

## SEE ALSO

[**WildMidi\_GetVersion**(3)](/WildMidi_GetVersion/3.md)**,** [**WildMidi\_MasterVolume**(3)](/WildMidi_MasterVolume/3.md)**,** [**WildMidi\_Open**(3)](/WildMidi_Open/3.md)**,** [**WildMidi\_OpenBuffer**(3)](/WildMidi_OpenBuffer/3.md)**,** [**WildMidi\_SetOption**(3)](/WildMidi_SetOption/3.md)**,** [**WildMidi\_GetOutput**(3)](/WildMidi_GetOutput/3.md)**,** [**WildMidi\_GetMidiOutput**(3)](/WildMidi_GetMidiOutput/3.md)**,** [**WildMidi\_GetInfo**(3)](/WildMidi_GetInfo/3.md)**,** [**WildMidi\_FastSeek**(3)](/WildMidi_FastSeek/3.md)**,** [**WildMidi\_Close**(3)](/WildMidi_Close/3.md)**,** [**WildMidi\_Shutdown**(3)](/WildMidi_Shutdown/3.md)**,** [**wildmidi.cfg**(5)](/wildmidi.cfg/5.md)

## AUTHOR

Chris Ison \<chrisisonwildcode@gmail.com\> Bret Curtis \<psi29a@gmail.com\>

## COPYRIGHT

Copyright (C) WildMidi Developers 2001-2016

This file is part of WildMIDI.

WildMIDI is free software: you can redistribute and/or modify the player under the terms of the GNU General Public License and you can redistribute and/or modify the library under the terms of the GNU Lesser General Public License as published by the Free Software Foundation, either version 3 of the licenses, or(at your option) any later version.

WildMIDI is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License and the GNU Lesser General Public License for more details.

You should have received a copy of the GNU General Public License and the GNU Lesser General Public License along with WildMIDI. If not, see \<http://www.gnu.org/licenses/\>.

This manpage is licensed under the Creative Commons Attribution-Share Alike 3.0 Unported License. To view a copy of this license, visit http://creativecommons.org/licenses/by-sa/3.0/ or send a letter to Creative Commons, 171 Second Street, Suite 300, San Francisco, California, 94105, USA.