feat(playback): add random variation on each keypress (#24)

[Xenira]

Description of change

Adds the possibility of random variation for each keypress

• Volume
• Tempo / Pitch

I added some values to the default preset. Maybe play around with those to find sensible defaults. ✔️

Closes #24

Configuration

I added configuration possibilities in 3 places:

1. CLI Arguments. These will override all settings defined in Presets.
2. KeyConfig in Preset. These will override settings defined in the parent Preset.
3. Preset. Will apply to all KeyConfigs that do not provide variation.

Currently the cli only accepts one value, that is used for both changes up and down, while the config file takes separate values. I am looking into a convenient way to allow both for the cli as well.

The cli accepts (up to) two comma separated values. If only one is defined it is used for both.

How has this been tested? (if applicable)

• Set high values in config and use 👂
• Set high values in cli and use 👂
• Watch trace logs.

[codecov-commenter]

Codecov Report

Attention: 74 lines in your changes are missing coverage. Please review.

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Files	Coverage Δ
src/config.rs	30.90% <14.28%> (-1.13%)	⬇️
src/lib.rs	0.00% <0.00%> (ø)
src/main.rs	0.00% <0.00%> (ø)
src/args.rs	16.12% <0.00%> (-25.54%)	⬇️
src/app.rs	0.00% <0.00%> (ø)

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[orhun]

The code looks pretty good! I tried it out and works as expected. Also, left a comment about changing the pitch in #24

Feel free to rebase main and update docs when you have time.

cc @arda-guler for testing / finding the most sane defaults.

[arda-guler]

Yeah, well, regarding that "finding the most sane defaults" thing and the pitch implementation...

The indirect implementation here by changing the speed is more than adequate enough IMO. In fact, I'm going to say that as far as my own opinion goes, a 0.1 volume variation and a 0.05 tempo variation sounds so much better - the current example values are a bit too pronounced. It should be a little more subtle.

All else is very good!

[Xenira]

Sorry for the git history confusion... Forgot to sign and messed up fixing it... 🤦

[orhun]

Great stuff!