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frame.ts
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frame.ts
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/**
* @license
* Copyright 2019 Google LLC. All Rights Reserved.
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
* =============================================================================
*/
import {Tensor, Tensor1D} from '../../tensor';
import {concat} from '../concat';
import {fill} from '../fill';
import {op} from '../operation';
import {reshape} from '../reshape';
import {slice} from '../slice';
import {tensor2d} from '../tensor2d';
/**
* Expands input into frames of frameLength.
* Slides a window size with frameStep.
*
* ```js
* tf.signal.frame([1, 2, 3], 2, 1).print();
* ```
* @param signal The input tensor to be expanded
* @param frameLength Length of each frame
* @param frameStep The frame hop size in samples.
* @param padEnd Whether to pad the end of signal with padValue.
* @param padValue A number to use where the input signal does
* not exist when padEnd is True.
*
* @doc {heading: 'Operations', subheading: 'Signal', namespace: 'signal'}
*/
function frame_(
signal: Tensor1D, frameLength: number, frameStep: number, padEnd = false,
padValue = 0): Tensor {
let start = 0;
const output: Tensor[] = [];
while (start + frameLength <= signal.size) {
output.push(slice(signal, start, frameLength));
start += frameStep;
}
if (padEnd) {
while (start < signal.size) {
const padLen = (start + frameLength) - signal.size;
const pad = concat([
slice(signal, start, frameLength - padLen), fill([padLen], padValue)
]);
output.push(pad);
start += frameStep;
}
}
if (output.length === 0) {
return tensor2d([], [0, frameLength]);
}
return reshape(concat(output), [output.length, frameLength]);
}
export const frame = /* @__PURE__ */ op({frame_});