Question about acmStreamOpen and others

I am now starting to work on audio streaming and I am going to use waveIn and waveOut APIs because overall they provide the best functionality and flexibility over the other audio APIs.

Below is a list of some ACM functions I found. There could be more but I don't know that.

My question is what is the purpose of these functions? Are they to do with audio streaming and if so how are they used? Also, are they needed to do audio streaming or can I perform streaming without these APIs?

acmStreamOpen
acmStreamClose
acmStreamPrepareHeader
acmStreamUnprepareHeader
acmStreamConvert
acmStreamReset
acmStreamSize