Repository: pytorch/audio

Issue #689: Revise parameters for Kaldi mfcc compatibility test
Created: 2020-06-04T13:15:31Z
Similar to #679
We should also revise the parameters for mfcc test.
See also #681

Duplicate issue #679: Revise parameters for Kaldi fbank compatibility test
Created: 2020-06-03T14:38:34Z
Test parameters for Kaldi fbank were generated using this script, but this does not necessarily generate values in valid range, so we need to revise them.
First, we need to test the parity of default values.

$ compute-fbank-feats --help

Create Mel-filter bank (FBANK) feature files.
Usage:  compute-fbank-feats [options...] <wav-rspecifier> <feats-wspecifier>

Options:
  --allow-downsample          : If true, allow the input waveform to have a higher frequency than the specified --sample-frequency (and we'll downsample). (bool, default = false)
  --allow-upsample            : If true, allow the input waveform to have a lower frequency than the specified --sample-frequency (and we'll upsample). (bool, default = false)
  --blackman-coeff            : Constant coefficient for generalized Blackman window. (float, default = 0.42)
  --channel                   : Channel to extract (-1 -> expect mono, 0 -> left, 1 -> right) (int, default = -1)
  --debug-mel                 : Print out debugging information for mel bin computation (bool, default = false)
  --dither                    : Dithering constant (0.0 means no dither). If you turn this off, you should set the --energy-floor option, e.g. to 1.0 or 0.1 (float, default = 1)
  --energy-floor              : Floor on energy (absolute, not relative) in FBANK computation. Only makes a difference if --use-energy=true; only necessary if --dither=0.0.  Suggested values: 0.1 or 1.0 (float, default = 0)
  --frame-length              : Frame length in milliseconds (float, default = 25)
  --frame-shift               : Frame shift in milliseconds (float, default = 10)
  --high-freq                 : High cutoff frequency for mel bins (if <= 0, offset from Nyquist) (float, default = 0)
  --htk-compat                : If true, put energy last.  Warning: not sufficient to get HTK compatible features (need to change other parameters). (bool, default = false)
  --low-freq                  : Low cutoff frequency for mel bins (float, default = 20)
  --max-feature-vectors       : Memory optimization. If larger than 0, periodically remove feature vectors so that only this number of the latest feature vectors is retained. (int, default = -1)
  --min-duration              : Minimum duration of segments to process (in seconds). (float, default = 0)
  --num-mel-bins              : Number of triangular mel-frequency bins (int, default = 23)
  --output-format             : Format of the output files [kaldi, htk] (string, default = "kaldi")
  --preemphasis-coefficient   : Coefficient for use in signal preemphasis (float, default = 0.97)
  --raw-energy                : If true, compute energy before preemphasis and windowing (bool, default = true)
  --remove-dc-offset          : Subtract mean from waveform on each frame (bool, default = true)
  --round-to-power-of-two     : If true, round window size to power of two by zero-padding input to FFT. (bool, default = true)
  --sample-frequency          : Waveform data sample frequency (must match the waveform file, if specified there) (float, default = 16000)
  --snip-edges                : If true, end effects will be handled by outputting only frames that completely fit in the file, and the number of frames depends on the frame-length.  If false, the number of frames depends only on the frame-shift, and we reflect the data at the ends. (bool, default = true)
  --subtract-mean             : Subtract mean of each feature file [CMS]; not recommended to do it this way.  (bool, default = false)
  --use-energy                : Add an extra dimension with energy to the FBANK output. (bool, default = false)
  --use-log-fbank             : If true, produce log-filterbank, else produce linear. (bool, default = true)
  --use-power                 : If true, use power, else use magnitude. (bool, default = true)
  --utt2spk                   : Utterance to speaker-id map (if doing VTLN and you have warps per speaker) (string, default = "")
  --vtln-high                 : High inflection point in piecewise linear VTLN warping function (if negative, offset from high-mel-freq (float, default = -500)
  --vtln-low                  : Low inflection point in piecewise linear VTLN warping function (float, default = 100)
  --vtln-map                  : Map from utterance or speaker-id to vtln warp factor (rspecifier) (string, default = "")
  --vtln-warp                 : Vtln warp factor (only applicable if vtln-map not specified) (float, default = 1)
  --window-type               : Type of window ("hamming"|"hanning"|"povey"|"rectangular"|"sine"|"blackmann") (string, default = "povey")
  --write-utt2dur             : Wspecifier to write duration of each utterance in seconds, e.g. 'ark,t:utt2dur'. (string, default = "")

Standard options:
  --config                    : Configuration file to read (this option may be repeated) (string, default = "")
  --help                      : Print out usage message (bool, default = false)
  --print-args                : Print the command line arguments (to stderr) (bool, default = true)
  --verbose                   : Verbose level (higher->more logging) (int, default = 0)


Second, we should cover values found in Kaldi examples. such as

Switchboard
WSJ
Fisher Switchboard
CSJ
CHiME-1,2,3, CHiME-4 1ch, 2ch, 6ch, CHiME-5, CHiME-6 Track1, Track2
Callhome
librispeech
TIMIT

Then we can also add perturbation

--frame-length and --frame-shift: integer value around 10 - 50 [ms] if perturbing
--preemphasis-coefficient: less than 1.0, around 0.90 - 0.99
--low-freq: around 20 - 50 (and less than --high-freq)

See also #672

Closing comment (2020-07-16T18:47:51Z): @mthrok since this is so related to #689, I would like to work on this as well.

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