Audio Compression Manager Functions and Structures

The ACM functions fall into several categories. Naming conventions for the functions make it easy to identify these categories. Function names (with two exceptions) are of the form acmGroupFunction, where Group designates the ACM category (such as  Driver,   Format,   FormatTag,   Filter,   FilterTag,  or  Stream ), and Function describes the action performed by the function.

The functions in the filter and format groups are very similar. Almost every function that acts on filters has a parallel function that acts on formats.

In the format group, some functions use waveform-audio format tags (the wFormatTag member of a WAVEFORMATEX2R_J_MS structure) while others require full waveform-audio formats (the full WAVEFORMATEX structure). (For reference information about the WAVEFORMATEX structure, see Error47Q9_QH.)

In the filter group, some functions use waveform-audio filter tags (the dwFilterTag member of a WAVEFILTER211WF9H structure), while others require full waveform-audio filters (the full WAVEFILTER structure).

The functions in the stream group represent the many steps involved in a conversion: opening a conversion instance, preparing for the conversion, performing the conversion, cleaning up after the conversion is complete, and closing the conversion instance.