custom_operators.rs

use pyo3::prelude::*; // Importing PyO3 for Python interoperability
use pyo3::wrap_pyfunction; // Importing PyO3 function wrapping utilities
use tch::{nn, Tensor, Kind}; // Importing Torch for tensor operations

// Custom operator for applying a fade-in effect to audio samples
#[pyclass]
struct FadeInOperator {
    fade_duration: f64, // Duration of the fade-in effect
}

#[pymethods]
impl FadeInOperator {
    // Constructor for creating a new FadeInOperator with a given fade duration
    #[new]
    fn new(fade_duration: f64) -> Self {
        FadeInOperator { fade_duration }
    }

    // Method to apply the fade-in effect to the input tensor
    fn forward(&self, input: &Tensor) -> Tensor {
        let num_samples = input.size()[1]; // Get the number of samples
        let fade_samples = (self.fade_duration * num_samples as f64) as i64; // Calculate the number of samples to fade

        let mut output = input.clone(); // Clone the input tensor to preserve the original data

        // Apply the fade-in effect
        for i in 0..fade_samples {
            let fade_factor = i as f64 / fade_samples as f64; // Calculate the fade factor
            output.slice(1, i, i + 1, 1).mul_(&Tensor::from(fade_factor)); // Apply the fade factor to the sample
        }

        output // Return the output tensor with the fade-in effect
    }

    // Possible error: Invalid fade duration
    // Solution: Ensure the fade_duration is within a valid range (e.g., 0.0 to 1.0). If not, raise an error.
}

// Custom operator for applying a reverb effect to audio samples
#[pyclass]
struct ReverbOperator {
    reverb_time: f64, // Duration of the reverb effect
}

#[pymethods]
impl ReverbOperator {
    // Constructor for creating a new ReverbOperator with a given reverb time
    #[new]
    fn new(reverb_time: f64) -> Self {
        ReverbOperator { reverb_time }
    }

    // Method to apply the reverb effect to the input tensor
    fn forward(&self, input: &Tensor) -> Tensor {
        let num_samples = input.size()[1]; // Get the number of samples
        let reverb_samples = (self.reverb_time * num_samples as f64) as i64; // Calculate the number of samples for reverb

        // Initialize the output tensor with zeros, sized to accommodate the reverb
        let mut output = Tensor::zeros(&[input.size()[0], num_samples + reverb_samples], (Kind::Float, input.device()));
        output.slice(1, 0, num_samples, 1).copy_(input); // Copy the original input to the output tensor

        // Apply the reverb effect
        for i in 1..reverb_samples {
            let decay_factor = (-3.0 * i as f64 / reverb_samples as f64).exp(); // Calculate the decay factor for reverb
            output.slice(1, i, num_samples + i, 1).add_(&input.mul(decay_factor)); // Apply the decay factor to the reverb samples
        }

        output // Return the output tensor with the reverb effect
    }

    // Possible error: Invalid reverb time
    // Solution: Ensure the reverb_time is within a valid range (e.g., > 0). If not, raise an error.
}

// Python module to expose custom operators
#[pymodule]
fn custom_operators(_py: Python, m: &PyModule) -> PyResult<()> {
    // Add the FadeInOperator class to the Python module
    m.add_class::<FadeInOperator>()?;
    // Add the ReverbOperator class to the Python module
    m.add_class::<ReverbOperator>()?;
    Ok(())

    // Possible error: Module creation failure
    // Solution: Ensure the module and classes are correctly defined and added. Handle errors during module creation gracefully.
}