feat: YIN algorithm

[winkt0]

YIN algorithm

Description

Implementation of the YIN algorithm for estimating the fundamental frequency of an audio signal. With optional parabolic interpretation for refining the result. I added the following files:

signal_analysis/yin.rs
signal_analysis/mod.rs

I added a new folder signal_analysis because I felt the algorithm did not feat neatly into the other categories. Let me know if that's okay or I should put it somewhere else.

I added #[allow(clippy::needless_range_loop)] on the function difference_function_values because I felt that clippy's suggestion to use an iterator and enumerate decreases the readability of the function (especially for people new to Rust) for no substantial performance improvement.

The YIN algorithm is based on: De Cheveigné, A., & Kawahara, H. (2002). YIN, a fundamental frequency estimator for speech and music. The Journal of the Acoustical Society of America, 111(4), 1917–1930. https://doi.org/10.1121/1.1458024

Closes #939

Type of change

Please delete options that are not relevant.

• New feature (non-breaking change which adds functionality)

Checklist:

• I ran bellow commands using the latest version of rust nightly.
• I ran cargo clippy --all -- -D warnings just before my last commit and fixed any issue that was found.
• I ran cargo fmt just before my last commit.
• I ran cargo test just before my last commit and all tests passed.
• I added my algorithm to the corresponding mod.rs file within its own folder, and in any parent folder(s).
• I added my algorithm to DIRECTORY.md with the correct link.
• I checked COUNTRIBUTING.md and my code follows its guidelines.

[winkt0]

Hi @siriak, can you check this pr when you get a chance? Thanks in advance!

[Copilot]

Pull Request Overview

This PR implements the YIN algorithm for pitch detection in audio signals, adding a new signal_analysis module to the codebase. The YIN algorithm is a well-known pitch estimation technique that uses autocorrelation-based methods to detect fundamental frequencies in audio signals.

• Implements the complete YIN algorithm including difference function, cumulative mean normalized difference function, and parabolic interpolation for improved accuracy
• Adds comprehensive test coverage with various sine wave scenarios including harmonic and inharmonic combinations
• Integrates the new module into the project structure with proper exports and documentation

Reviewed Changes

Copilot reviewed 4 out of 4 changed files in this pull request and generated 2 comments.

File	Description
src/signal_analysis/yin.rs	Implements the YIN pitch detection algorithm with Yin struct, YinResult struct, and supporting functions for signal analysis
src/signal_analysis/mod.rs	Module file that exports the Yin and YinResult types
src/lib.rs	Adds the signal_analysis module to the public API
DIRECTORY.md	Updates documentation to include the new YIN implementation

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[codecov-commenter]

Codecov Report

❌ Patch coverage is 99.57447% with 1 line in your changes missing coverage. Please review.
✅ Project coverage is 95.44%. Comparing base (db3f011) to head (a30b9d7).

Files with missing lines	Patch %	Lines
src/signal_analysis/yin.rs	99.57%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##           master     #940      +/-   ##
==========================================
+ Coverage   95.39%   95.44%   +0.04%     
==========================================
  Files         331      332       +1     
  Lines       21261    21496     +235     
==========================================
+ Hits        20282    20516     +234     
- Misses        979      980       +1     

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[siriak]

Please check comments

[winkt0]

I adjusted the relevant code as suggested

[siriak]

Looks good, thanks!