Each plugin host has its own soundfile input facilities. For example, in SuperCollider, one often reads an entire soundfile into an instance of the Buffer class using the Buffer.read method. Similarly, pd has a soundfiler object for reading a soundfile into a table in memory (see, for example, the pd Help Browser at Pure Data / 2.audio.examples / B07.sampler.pd). Finally, typical VST plugin hosts have extensive facilities for reading, writing, and manipulating sound clips, plugin parameters, and so on.