kaldifeat 1.2

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kaldifeat

Feature extraction compatible with Kaldi using PyTorch, supporting CUDA, batch processing, chunk processing, and autograd.

Usage

Let us first generate a test wave using sox:

# generate a wave of 1.2 seconds, containing a sine-wave
# swept from 300 Hz to 3300 Hz
sox -n -r 16000 -b 16 test.wav synth 1.2 sine 300-3300

HINT: Download test_wav.

Fbank

import torchaudio

import kaldifeat

filename = "./test.wav"
wave, samp_freq = torchaudio.load(filename)

wave = wave.squeeze()

opts = kaldifeat.FbankOptions()
opts.frame_opts.dither = 0
# Yes, it has same options like `Kaldi`

fbank = kaldifeat.Fbank(opts)
features = fbank(wave)

To compute features that are compatible with Kaldi, wave samples have to be scaled to the range [-32768, 32768]. WARNING: You don't have to do this if you don't care about the compatibility with Kaldi

The following is an example:

wave *= 32768
fbank = kaldifeat.Fbank(opts)
features = fbank(wave)
print(features[:3])

The output is:

tensor([[15.0074, 21.1730, 25.5286, 24.4644, 16.6994, 13.8480, 11.2087, 11.7952,
         10.3911, 10.4491, 10.3012,  9.8743,  9.6997,  9.3751,  9.3476,  9.3559,
          9.1074,  9.0032,  9.0312,  8.8399,  9.0822,  8.7442,  8.4023],
        [13.8785, 20.5647, 25.4956, 24.6966, 16.9541, 13.9163, 11.3364, 11.8449,
         10.2565, 10.5871, 10.3484,  9.7474,  9.6123,  9.3964,  9.0695,  9.1177,
          8.9136,  8.8425,  8.5920,  8.8315,  8.6226,  8.8605,  8.9763],
        [13.9475, 19.9410, 25.4494, 24.9051, 17.0004, 13.9207, 11.6667, 11.8217,
         10.3411, 10.7258, 10.0983,  9.8109,  9.6762,  9.4218,  9.1246,  8.7744,
          9.0863,  8.7488,  8.4695,  8.6710,  8.7728,  8.7405,  8.9824]])

You can compute the fbank feature for the same wave with Kaldi using the following commands:

echo "1 test.wav" > test.scp
compute-fbank-feats --dither=0 scp:test.scp ark,t:test.txt
head -n4 test.txt

The output is:

1  [
  15.00744 21.17303 25.52861 24.46438 16.69938 13.84804 11.2087 11.79517 10.3911 10.44909 10.30123 9.874329 9.699727 9.37509 9.347578 9.355928 9.107419 9.00323 9.031268 8.839916 9.082197 8.744139 8.40221
  13.87853 20.56466 25.49562 24.69662 16.9541 13.91633 11.33638 11.84495 10.25656 10.58718 10.34841 9.747416 9.612316 9.39642 9.06955 9.117751 8.913527 8.842571 8.59212 8.831518 8.622513 8.86048 8.976251
  13.94753 19.94101 25.4494 24.90511 17.00044 13.92074 11.66673 11.82172 10.34108 10.72575 10.09829 9.810879 9.676199 9.421767 9.124647 8.774353 9.086291 8.74897 8.469534 8.670973 8.772754 8.740549 8.982433

You can see that kaldifeat produces the same output as Kaldi (within some tolerance due to numerical precision).

HINT: Download test_scp and test_txt.

To use GPU, you can use:

import torch

opts = kaldifeat.FbankOptions()
opts.device = torch.device("cuda", 0)

fbank = kaldifeat.Fbank(opts)
features = fbank(wave.to(opts.device))

MFCC

To compute MFCC features, please replace kaldifeat.FbankOptions and kaldifeat.Fbank with kaldifeat.MfccOptions and kaldifeat.Mfcc, respectively.

Please refer to kaldifeat/python/tests/test_fbank.py and kaldifeat/python/tests/test_mfcc.py for more examples.

HINT: In the examples, you can find that

• kaldifeat supports batch processing as well as chunk processing
• kaldifeat uses the same options as Kaldi's compute-fbank-feats and compute-mfcc-feats

Installation

From PyPi with pip

If you install kaldifeat using pip, it will also install PyTorch 1.8.1. If this is not what you want, please install kaldifeat from source (see below).

pip install kaldifeat

From source

The following are the commands to compile kaldifeat from source. We assume that you have installed cmake and PyTorch. cmake 3.11 is known to work. Other cmake versions may also work. PyTorch 1.8.1 is known to work. Other PyTorch versions may also work.

mkdir /some/path
git clone https://github.com/csukuangfj/kaldifeat.git
cd kaldifeat
python setup.py install

To test whether kaldifeat was installed successfully, you can run:

python3 -c "import kaldifeat; print(kaldifeat.__version__)"