Win32/WASAPI: suggestion: improve symbol names for the "stereo to mono mixer" code

[RossBencina]

[Hi Dmitry, this is just a suggestion for changing internal function names. I'm not proposing to have a lengthy debate. Please close this issue if you don't want to action it]

During the review of #934 I had a bit of confusion about the meaning of the phrase "internal stereo to mono mixer" in a comment.

Upon review of the code in pa_win_wasapi.c I see that there is a mechanism for selecting functions for changing channel count: GetMonoToStereoMixer, it is called on line 3339:

pSub->monoMixer = GetMonoToStereoMixer(&pSub->wavexu.ext, (output ? MIX_DIR__1TO2 : MIX_DIR__2TO1_L));

Note that this function, and the functions that it calls are used for 2->1 mixing or channel selection for input, or 1->2 channel duplication for output. There are two sources of confusion:

• In only one of 3 cases is this a "mixer". Otherwise it is a "selector" or a "duplicator". So I think it is better to avoid the terms "mix" and "mixer". A general term would be "converter".
• In the output case it is "mono to stereo" but for the input case it is "stereo to mono", however the text MonoToStereo is used throughout the code. This could be changed to use MonoToStereo and StereoToMono consistent with behavior, but since 2TO1 and 1TO2 also appear but might be possible to just avoid it in most cases. Another option is MonoStereo which does not name a direction.

I think it is good to aim to reduce the amount of confusion in the code base. Here are some options:

pSub->monoStereoConverter = GetMonoStereoConverter(&pSub->wavexu.ext, (output ? CONVERT__1TO2 : CONVERT_2TO1_L));

or

pSub->monoStereoConverter = output ? GetMonoToStereoConverter(&pSub->wavexu.ext) :  GetStereoToMonoConverter(&pSub->wavexu.ext, CONVERT__2TO1_L);

Then I would change the name of in individual converters:

_StereoToMono_2TO1_8, _MonoToStereo_1TO2_24

or, probably better:

_Convert_2TO1_8, _Convert_1TO2_24

Hope you see what I mean.

Thank you.

[dmitrykos]

Hi Ross! I like your proposal, it will improve code readability indeed.

I would choose:

pSub->monoStereoConverter = GetMonoStereoConverter(&pSub->wavexu.ext, (output ? CONVERT__1TO2 : CONVERT_2TO1_L));

and:

_Convert_2TO1_8, _Convert_1TO2_24

Once PRs touching this area are merged, will create new one to address this issue.