| 1 | /**
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| 2 | * @license
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| 3 | * Copyright 2019 Google LLC. All Rights Reserved.
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| 4 | * Licensed under the Apache License, Version 2.0 (the "License");
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| 5 | * you may not use this file except in compliance with the License.
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| 6 | * You may obtain a copy of the License at
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| 7 | *
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| 8 | * http://www.apache.org/licenses/LICENSE-2.0
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| 9 | *
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| 10 | * Unless required by applicable law or agreed to in writing, software
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| 11 | * distributed under the License is distributed on an "AS IS" BASIS,
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| 12 | * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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| 13 | * See the License for the specific language governing permissions and
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| 14 | * limitations under the License.
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| 15 | * =============================================================================
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| 16 | */
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| 17 | import { mul } from '../mul';
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| 18 | import { op } from '../operation';
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| 19 | import { enclosingPowerOfTwo } from '../signal_ops_util';
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| 20 | import { rfft } from '../spectral/rfft';
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| 21 | import { frame } from './frame';
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| 22 | import { hannWindow } from './hann_window';
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| 23 | /**
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| 24 | * Computes the Short-time Fourier Transform of signals
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| 25 | * See: https://en.wikipedia.org/wiki/Short-time_Fourier_transform
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| 26 | *
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| 27 | * ```js
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| 28 | * const input = tf.tensor1d([1, 1, 1, 1, 1])
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| 29 | * tf.signal.stft(input, 3, 1).print();
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| 30 | * ```
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| 31 | * @param signal 1-dimensional real value tensor.
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| 32 | * @param frameLength The window length of samples.
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| 33 | * @param frameStep The number of samples to step.
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| 34 | * @param fftLength The size of the FFT to apply.
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| 35 | * @param windowFn A callable that takes a window length and returns 1-d tensor.
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| 36 | *
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| 37 | * @doc {heading: 'Operations', subheading: 'Signal', namespace: 'signal'}
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| 38 | */
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| 39 | function stft_(signal, frameLength, frameStep, fftLength, windowFn = hannWindow) {
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| 40 | if (fftLength == null) {
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| 41 | fftLength = enclosingPowerOfTwo(frameLength);
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| 42 | }
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| 43 | const framedSignal = frame(signal, frameLength, frameStep);
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| 44 | const windowedSignal = mul(framedSignal, windowFn(frameLength));
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| 45 | return rfft(windowedSignal, fftLength);
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| 46 | }
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| 47 | export const stft = op({ stft_ });
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| 48 | //# sourceMappingURL=stft.js.map |
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