Soundfile ports

Soundfile ports are currently only supported with the ossia binding.

They allow to define an input which will be the content of a sound file, along with its metadata: number of channels, number of frames.

Port definition

A soundfile input port looks like this:

  static consteval auto name() { return "My soundfile"}
  struct {
    const float** data{}; // The audio channels
    int64_t frames{}; // How many samples are there in a channel
    int32_t channels{}; // How many channels are there
    std::string_view filename; // Currently loaded soundfile
  } soundfile;
} snd;

A helper type is provided:

struct {
  halp::soundfile_port<"My soundfile"> snd;
} inputs;

void operator()(int frames) {
  // Check if a soundfile is loaded:

  // Access things through helpers
  const int channels = inputs.snd.channels();
  const int frames = inputs.snd.frames();
  std::span<const float> chan =;

  // Or manually...
  for(int i = 0; i < channels; i++)
    for(int j = 0; j < frames; j++)

It allows choosing the sample format in which the samples are loaded:

halp::soundfile_port<"My soundfile", float> snd_float;
halp::soundfile_port<"My soundfile", double> snd_double;


Like other ports, it is possible to get an update callback, by implementing an update method ; the simplest way is to make an empty struct which inherits from halp::soundfile

struct : halp::soundfile_port<"My soundfile"> {
  void update(MyObject& obj) {
    // This code is called whenever the soundfile has been changed by the user
} port_name;