Examples of low level control (synthesis) of audio ? - speakers, HDMI audio

[Stephen Tashiro]

Are there good explanations or examples of code for low level 
control of audio in Dlang?

I assume that all high level audio synthesis programs (music, 
speech synthesis, etc.) rely on some common method of outputing 
sound.  I also assume the output to analog speakers must be 
different code than output over HDMI.  Is that correct?

I visualize the final output as data that stores a waveform as a 
sequence of values that represent amplitudes.  Is that low level 
of representation necessary? - or do modern speakers and audio 
devices have built-in programs that accept more concise formats?