Metadata-Version: 2.1
Name: noisereduce
Version: 2.0.0
Summary: Noise reduction using Spectral Gating in python
Home-page: https://github.com/timsainb/noisereduce
Author: Tim Sainburg
License: MIT
Description: [![Build Status](https://travis-ci.com/timsainb/noisereduce.svg?branch=master)](https://travis-ci.com/timsainb/noisereduce)
        [![Coverage Status](https://coveralls.io/repos/github/timsainb/noisereduce/badge.svg?branch=master)](https://coveralls.io/github/timsainb/noisereduce?branch=master)
        [![Binder](https://mybinder.org/badge_logo.svg)](https://mybinder.org/v2/gh/timsainb/noisereduce/master?filepath=notebooks%2F1.0-test-noise-reduction.ipynb)
        [![Open In Colab](https://colab.research.google.com/assets/colab-badge.svg)](https://colab.research.google.com/github/timsainb/noisereduce/blob/master/notebooks/1.0-test-noise-reduction.ipynb)
        [![PyPI version](https://badge.fury.io/py/noisereduce.svg)](https://badge.fury.io/py/noisereduce)
        
        <div style="text-align:center">
        <p align="center">
          <img src="assets/noisereduce.png", width="100%">
        </p>
        </div>
        
        # Noise reduction in python using spectral gating
        Noisereduce is a noise reduction algorithm in python that reduces noise in time-domain signals like speech, bioacoustics, and physiological signals. It relies on a method called "spectral gating" which is a form of [Noise Gate](https://en.wikipedia.org/wiki/Noise_gate). It works by computing a spectrogram of a signal (and optionally a noise signal) and estimating a noise threshold (or gate) for each frequency band of that signal/noise. That threshold is used to compute a mask, which gates noise below the frequency-varying threshold. 
        
        The most recent version of noisereduce comprises two algorithms:
        1. **Stationary Noise Reduction**: Keeps the estimated noise threshold at the same level across the whole signal
        2. **Non-stationary Noise Reduction**: Continuously updates the estimated noise threshold over time
        
        ### Version 2 Updates:
        - Added two forms of spectral gating noise reduction: stationary noise reduction, and non-stationary noise reduction. 
        - Added multiprocessing so you can perform noise reduction on bigger data.
        - The new version breaks the API of the old version. 
        - The previous version is still available at `from noisereduce.noisereducev1 import reduce_noise`
        - You can now create a noisereduce object which allows you to reduce noise on subsets of longer recordings
        
        # Stationary Noise Reduction
        - The basic intuition is that statistics are calculated on  each frequency channel to determine a noise gate. Then the gate is applied to the signal.
        - This algorithm is based (but not completely reproducing) on the one [outlined by Audacity](https://wiki.audacityteam.org/wiki/How_Audacity_Noise_Reduction_Works) for the **noise reduction effect** ([Link to C++ code](https://github.com/audacity/audacity/blob/master/src/effects/NoiseReduction.cpp))
        - The algorithm takes two inputs: 
            1. A *noise* clip containing prototypical noise of clip (optional)
            2. A *signal* clip containing the signal and the noise intended to be removed
        
        ### Steps of the Stationary Noise Reduction algorithm
        1. A spectrogram is calculated over the noise audio clip
        2. Statistics are calculated over spectrogram of the the noise (in frequency)
        3. A threshold is calculated based upon the statistics of the noise (and the desired sensitivity of the algorithm) 
        4. A spectrogram is calculated over the signal
        5. A mask is determined by comparing the signal spectrogram to the threshold
        6. The mask is smoothed with a filter over frequency and time
        7. The mask is appled to the spectrogram of the signal, and is inverted
        *If the noise signal is not provided, the algorithm will treat the signal as the noise clip, which tends to work pretty well*
        
        # Non-stationary Noise Reduction
        - The non-stationary noise reduction algorithm is an extension of the stationary noise reduction algorithm, but allowing the noise gate to change over time. 
        - When you know the timescale that your signal occurs on (e.g. a bird call can be a few hundred milliseconds), you can set your noise threshold based on the assumption that events occuring on longer timescales are noise. 
        - This algorithm was motivated by a recent method in bioacoustics called Per-Channel Energy Normalization. 
        
        ### Steps of the Non-stationary Noise Reduction algorithm
        1. A spectrogram is calculated over the signal
        2. A time-smoothed version of the spectrogram is computed using an IIR filter aplied forward and backward on each frequency channel.
        3. A mask is computed based on that time-smoothed spectrogram
        4. The mask is smoothed with a filter over frequency and time
        5. The mask is appled to the spectrogram of the signal, and is inverted
        
        # Installation
        `pip install noisereduce`
        
        # Usage
        See example notebook: [![Open In Colab](https://colab.research.google.com/assets/colab-badge.svg)](https://colab.research.google.com/github/timsainb/noisereduce/blob/master/notebooks/1.0-test-noise-reduction.ipynb)
        
        
        ### Simplest usage
        ```
        import noisereduce as nr
        # load data
        rate, data = wavfile.read("mywav.wav")
        # perform noise reduction
        reduced_noise = nr.reduce_noise(y=data, sr=rate)
        ```
        
        ### Arguments to `reduce_noise`
        ```
        y : np.ndarray [shape=(# frames,) or (# channels, # frames)], real-valued
              input signal
          sr : int
              sample rate of input signal / noise signal
          y_noise : np.ndarray [shape=(# frames,) or (# channels, # frames)], real-valued
              noise signal to compute statistics over (only for non-stationary noise reduction).
          stationary : bool, optional
              Whether to perform stationary, or non-stationary noise reduction, by default False
          prop_decrease : float, optional
              The proportion to reduce the noise by (1.0 = 100%), by default 1.0
          time_constant_s : float, optional
              The time constant, in seconds, to compute the noise floor in the non-stationary
              algorithm, by default 2.0
          freq_mask_smooth_hz : int, optional
              The frequency range to smooth the mask over in Hz, by default 500
          time_mask_smooth_ms : int, optional
              The time range to smooth the mask over in milliseconds, by default 50
          thresh_n_mult_nonstationary : int, optional
              Only used in nonstationary noise reduction., by default 1
          sigmoid_slope_nonstationary : int, optional
              Only used in nonstationary noise reduction., by default 10
          n_std_thresh_stationary : int, optional
              Number of standard deviations above mean to place the threshold between
              signal and noise., by default 1.5
          tmp_folder : [type], optional
              Temp folder to write waveform to during parallel processing. Defaults to 
              default temp folder for python., by default None
          chunk_size : int, optional
              Size of signal chunks to reduce noise over. Larger sizes
              will take more space in memory, smaller sizes can take longer to compute.
              , by default 60000
              padding : int, optional
              How much to pad each chunk of signal by. Larger pads are
              needed for larger time constants., by default 30000
          n_fft : int, optional
              length of the windowed signal after padding with zeros.
              The number of rows in the STFT matrix ``D`` is ``(1 + n_fft/2)``.
              The default value, ``n_fft=2048`` samples, corresponds to a physical
              duration of 93 milliseconds at a sample rate of 22050 Hz, i.e. the
              default sample rate in librosa. This value is well adapted for music
              signals. However, in speech processing, the recommended value is 512,
              corresponding to 23 milliseconds at a sample rate of 22050 Hz.
              In any case, we recommend setting ``n_fft`` to a power of two for
              optimizing the speed of the fast Fourier transform (FFT) algorithm., by default 1024
          win_length : [type], optional
              Each frame of audio is windowed by ``window`` of length ``win_length``
              and then padded with zeros to match ``n_fft``.
              Smaller values improve the temporal resolution of the STFT (i.e. the
              ability to discriminate impulses that are closely spaced in time)
              at the expense of frequency resolution (i.e. the ability to discriminate
              pure tones that are closely spaced in frequency). This effect is known
              as the time-frequency localization trade-off and needs to be adjusted
              according to the properties of the input signal ``y``.
              If unspecified, defaults to ``win_length = n_fft``., by default None
          hop_length : [type], optional
              number of audio samples between adjacent STFT columns.
              Smaller values increase the number of columns in ``D`` without
              affecting the frequency resolution of the STFT.
              If unspecified, defaults to ``win_length // 4`` (see below)., by default None
          n_jobs : int, optional
              Number of parallel jobs to run. Set at -1 to use all CPU cores, by default 1
        ```
        
        
        
        
        ### Citation
        If you use this code in your research, please cite it:
        ```
        @software{tim_sainburg_2019_3243139,
          author       = {Tim Sainburg},
          title        = {timsainb/noisereduce: v1.0},
          month        = jun,
          year         = 2019,
          publisher    = {Zenodo},
          version      = {db94fe2},
          doi          = {10.5281/zenodo.3243139},
          url          = {https://doi.org/10.5281/zenodo.3243139}
        }
        
        
        @article{sainburg2020finding,
          title={Finding, visualizing, and quantifying latent structure across diverse animal vocal repertoires},
          author={Sainburg, Tim and Thielk, Marvin and Gentner, Timothy Q},
          journal={PLoS computational biology},
          volume={16},
          number={10},
          pages={e1008228},
          year={2020},
          publisher={Public Library of Science}
        }
        ```
        --------
        
        <p><small>Project based on the <a target="_blank" href="https://drivendata.github.io/cookiecutter-data-science/">cookiecutter data science project template</a>. #cookiecutterdatascience</small></p>
        
Platform: UNKNOWN
Classifier: Programming Language :: Python :: 3
Classifier: License :: OSI Approved :: BSD License
Classifier: Operating System :: OS Independent
Classifier: Intended Audience :: Science/Research
Classifier: Topic :: Education
Classifier: Topic :: Scientific/Engineering
Description-Content-Type: text/markdown
Provides-Extra: Tensorflow
