stft¶
- paddle.signal. stft ( x, n_fft, hop_length=None, win_length=None, window=None, center=True, pad_mode='reflect', normalized=False, onesided=True, name=None ) [source]
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Short-time Fourier transform (STFT).
The STFT computes the discrete Fourier transforms (DFT) of short overlapping windows of the input using this formula:
\[X_t[\omega] = \sum_{n = 0}^{N-1}% ext{window}[n]\ x[t imes H + n]\ % e^{-{2 \pi j \omega n}/{N}}\]Where: - \(t\): The \(t\)-th input window. - \(\omega\): Frequency \(0 \leq \omega < ext{n\_fft}\) for onesided=False,
or :math:`0 leq omega < lfloor ext{n_fft} / 2
- floor + 1` for onesided=True.
-
\(N\): Value of n_fft.
\(H\): Value of hop_length.
- Args:
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- x (Tensor): The input data which is a 1-dimensional or 2-dimensional Tensor with
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shape […, seq_length]. It can be a real-valued or a complex Tensor.
n_fft (int): The number of input samples to perform Fourier transform. hop_length (int, optional): Number of steps to advance between adjacent windows
and 0 < hop_length. Default: None`(treated as equal to `n_fft//4)
- win_length (int, optional): The size of window. Default: `None`(treated as equal
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to n_fft)
- window (Tensor, optional): A 1-dimensional tensor of size win_length. It will
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be center padded to length n_fft if win_length < n_fft. Default: None`( treated as a rectangle window with value equal to 1 of size `win_length).
- center (bool, optional): Whether to pad x to make that the
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\(t imes hop\_length\) at the center of \(t\)-th frame. Default: True.
- pad_mode (str, optional): Choose padding pattern when center is True. See
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paddle.nn.functional.pad for all padding options. Default: “reflect”
- normalized (bool, optional): Control whether to scale the output by 1/sqrt(n_fft).
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Default: False
- onesided (bool, optional): Control whether to return half of the Fourier transform
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output that satisfies the conjugate symmetry condition when input is a real-valued tensor. It can not be True if input is a complex tensor. Default: True
- name (str, optional): The default value is None. Normally there is no need for user
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to set this property. For more information, please refer to Name.
- Returns:
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- The complex STFT output tensor with shape `[…, n_fft//2 + 1, num_frames]`(
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real-valued input and onesided is True) or […, n_fft, num_frames]`( `onesided is False)
- Examples:
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import paddle from paddle.signal import stft # real-valued input x = paddle.randn([8, 48000], dtype=paddle.float64) y1 = stft(x, n_fft=512) # [8, 257, 376] y2 = stft(x, n_fft=512, onesided=False) # [8, 512, 376] # complex input x = paddle.randn([8, 48000], dtype=paddle.float64) + paddle.randn([8, 48000], dtype=paddle.float64)*1j # [8, 48000] complex128 y1 = stft(x, n_fft=512, center=False, onesided=False) # [8, 512, 372]