113 lines
3.6 KiB
Python
113 lines
3.6 KiB
Python
from __future__ import annotations
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import typing as T
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from dataclasses import dataclass
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from enum import Enum
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@dataclass(frozen=True)
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class SpectrogramParams:
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"""
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Parameters for the conversion from audio to spectrograms to images and back.
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Includes helpers to convert to and from EXIF tags, allowing these parameters to be stored
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within spectrogram images.
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"""
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# Whether the audio is stereo or mono
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stereo: bool = False
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# FFT parameters
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sample_rate: int = 44100
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step_size_ms: int = 10
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window_duration_ms: int = 100
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padded_duration_ms: int = 400
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# Mel scale parameters
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num_frequencies: int = 512
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# TODO(hayk): Set these to [20, 20000] for newer models
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min_frequency: int = 0
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max_frequency: int = 10000
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mel_scale_norm: T.Optional[str] = None
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mel_scale_type: str = "htk"
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max_mel_iters: int = 200
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# Griffin Lim parameters
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num_griffin_lim_iters: int = 32
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# Image parameterization
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power_for_image: float = 0.25
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class ExifTags(Enum):
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"""
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Custom EXIF tags for the spectrogram image.
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"""
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SAMPLE_RATE = 11000
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STEREO = 11005
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STEP_SIZE_MS = 11010
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WINDOW_DURATION_MS = 11020
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PADDED_DURATION_MS = 11030
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NUM_FREQUENCIES = 11040
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MIN_FREQUENCY = 11050
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MAX_FREQUENCY = 11060
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POWER_FOR_IMAGE = 11070
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MAX_VALUE = 11080
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@property
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def n_fft(self) -> int:
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"""
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The number of samples in each STFT window, with padding.
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"""
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return int(self.padded_duration_ms / 1000.0 * self.sample_rate)
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@property
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def win_length(self) -> int:
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"""
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The number of samples in each STFT window.
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"""
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return int(self.window_duration_ms / 1000.0 * self.sample_rate)
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@property
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def hop_length(self) -> int:
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"""
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The number of samples between each STFT window.
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"""
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return int(self.step_size_ms / 1000.0 * self.sample_rate)
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def to_exif(self) -> T.Dict[int, T.Any]:
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"""
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Return a dictionary of EXIF tags for the current values.
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"""
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return {
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self.ExifTags.SAMPLE_RATE.value: self.sample_rate,
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self.ExifTags.STEREO.value: self.stereo,
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self.ExifTags.STEP_SIZE_MS.value: self.step_size_ms,
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self.ExifTags.WINDOW_DURATION_MS.value: self.window_duration_ms,
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self.ExifTags.PADDED_DURATION_MS.value: self.padded_duration_ms,
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self.ExifTags.NUM_FREQUENCIES.value: self.num_frequencies,
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self.ExifTags.MIN_FREQUENCY.value: self.min_frequency,
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self.ExifTags.MAX_FREQUENCY.value: self.max_frequency,
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self.ExifTags.POWER_FOR_IMAGE.value: float(self.power_for_image),
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}
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@classmethod
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def from_exif(cls, exif: T.Mapping[int, T.Any]) -> SpectrogramParams:
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"""
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Create a SpectrogramParams object from the EXIF tags of the given image.
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"""
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# TODO(hayk): Handle missing tags
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return cls(
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sample_rate=exif[cls.ExifTags.SAMPLE_RATE.value],
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stereo=bool(exif[cls.ExifTags.STEREO.value]),
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step_size_ms=exif[cls.ExifTags.STEP_SIZE_MS.value],
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window_duration_ms=exif[cls.ExifTags.WINDOW_DURATION_MS.value],
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padded_duration_ms=exif[cls.ExifTags.PADDED_DURATION_MS.value],
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num_frequencies=exif[cls.ExifTags.NUM_FREQUENCIES.value],
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min_frequency=exif[cls.ExifTags.MIN_FREQUENCY.value],
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max_frequency=exif[cls.ExifTags.MAX_FREQUENCY.value],
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power_for_image=exif[cls.ExifTags.POWER_FOR_IMAGE.value],
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)
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