jomael / cmixer

Portable ANSI C audio mixer for games

cmixer

A lightweight, portable ANSI C audio mixer for games.

Features

• Easy to use
• Tiny: two files, around 600sloc
• No dependencies (stb_vorbis is optional)
• Support for wav and ogg files if stb_vorbis is used
• Simple API for adding custom formats
• Resampling and seamless looping
• Per-source gain, pan and pitch control
• Fast, fixed-point internal processing

Getting Started

The library's .c and .h files can be dropped into a project and compiled along with it. If ogg vorbis support is desired stb_vorbis.c should also be added to the project and the -DCM_USE_STB_VORBIS flag passed to the compiler.

Before use, the library should be initialized with the desired samplerate:

cm_init(44100);

A sound can be played by first creating a source, then calling cm_play() on that source.

cm_Source *src = cm_new_source_from_file("sound.wav");
cm_play(src);

When the cm_process() function is called, all the currently playing streams will be processed and mixed, the master output will be written to the provided 16bit buffer. This output is always stereo interlaced, thus the buffer length must always be an even number:

cm_Int16 buffer[512];
cm_process(buffer, 512);

cm_process() can safely be called from a separate thread; if more than one thread is used a lock event handler must be set:

static void lock_handler(cm_Event *e) {
  if (e->type == CM_EVENT_LOCK) {
    printf("acquired lock\n");
  }
  if (e->type == CM_EVENT_UNLOCK) {
    printf("released lock\n");
  }
}

cm_set_lock(lock_handler);

See doc/api.md for an overview of the API or demo for usage demos.

License

This library is free software; you can redistribute it and/or modify it under the terms of the MIT license. See LICENSE for details.