Introduction

The Speech Recognition Research Project, a university-sponsored initiative, was developed to study speech recognition in challenging environments with muffled speech or occluded microphones. A critical component of this research involved generating visualizations of audio files to help researchers analyze and understand the acoustic properties of speech under various constraints.

The original system was built in C++, utilizing specialized libraries like libsndfile for audio processing, FFTW for Fast Fourier Transform calculations, and CImg for image generation. While functional, the codebase presented maintenance challenges as most of the development team was more experienced with managed code platforms.

Original C++ Implementation

The C++ implementation leveraged three main libraries to create a pipeline for audio analysis and visualization:

  • libsndfile - Handled the loading of mono WAV files into memory
  • FFTW - Performed Fast Fourier Transform calculations for frequency analysis
  • CImg - Generated visualization images of both time-domain and frequency-domain data

The Refactoring Journey

To improve maintainability and align with the team's expertise, the decision was made to refactor the C++ codebase into C#. This transformation would leverage the .NET ecosystem while maintaining the core functionality of the audio visualization system.

xFactor with imported code

xFactor with Generated Code

xFactor was employed to transform the C++ codebase into a C# implementation. The refactoring process focused on maintaining the same functionality while leveraging .NET libraries such as NAudio for audio processing and System.Drawing for image generation.

Audio Sample and Visualizations

Below are three representations of the same audio data processed using the refactored C# code. The original audio sample can be played directly. The waveform visualization, generated by the SaveWaveformImage() method, shows the amplitude of the audio signal (white line) over time against a black background, indicating louder moments with higher peaks. The FFT visualization, created by the SaveFftImage() method, displays the frequency spectrum (green bars) of the audio.

Original Audio

Waveform Visualization

Waveform Visualization Example

FFT Visualization

FFT Visualization Example

Enhanced Code with Comments

After the initial code generation, xFactor's enhance code feature was used to add comprehensive comments. Note that line breaks were added to the main set of comments for improved readability.

Security Evaluation

Following the code generation, xFactor performed both a standard security assessment and a MITRE ATT&CK framework analysis of the refactored code, identifying potential risks and suggesting improvements.

Conclusion

The xFactor refactoring project successfully transformed a complex C++ audio visualization system into a more maintainable C# implementation. This migration not only preserved the core functionality of generating waveform and FFT visualizations but also aligned the codebase with the team's technical expertise. The security assessment provided valuable insights for further improvements, ensuring the system's robustness and security in its new form.

Refactoring code with xFactor