Sample accuracy for Rhythm Track

[SteveDaulton]

Resolves: #1837

tnzw wrote:

To me, I expect to have mathematical "perfect" timing has I am working on a computer. (i.e. for i in range(bars): at_abs = offset + i * beatlen

LWinterberg wrote:

I think that having it fully accurate is the more useful approach to put work in.

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• [x ] The title of the pull request describes an issue it addresses
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• [x ] Each commit's message describes its purpose and effects
• [x ] There are no behavior changes unnecessary for the stated purpose of the PR

Recommended:

• [x ] Each commit compiles and runs on my machine without known undesirable changes of behavior