@vladmandic/face-api/src/dom/toNetInput.ts

FaceAPI: AI-powered Face Detection & Rotation Tracking, Face Description & Recognition, Age & Gender & Emotion Prediction for Browser and NodeJS using TensorFlow/JS

import { isTensor3D, isTensor4D } from '../utils/index';
import { awaitMediaLoaded } from './awaitMediaLoaded';
import { isMediaElement } from './isMediaElement';
import { NetInput } from './NetInput';
import { resolveInput } from './resolveInput';
import { TNetInput } from './types';

/**
 * Validates the input to make sure, they are valid net inputs and awaits all media elements
 * to be finished loading.
 *
 * @param input The input, which can be a media element or an array of different media elements.
 * @returns A NetInput instance, which can be passed into one of the neural networks.
 */
export async function toNetInput(inputs: TNetInput): Promise<NetInput> {
  if (inputs instanceof NetInput) return inputs;
  const inputArgArray = Array.isArray(inputs) ? inputs : [inputs];
  if (!inputArgArray.length) throw new Error('toNetInput - empty array passed as input');
  const getIdxHint = (idx: number) => (Array.isArray(inputs) ? ` at input index ${idx}:` : '');
  const inputArray = inputArgArray.map(resolveInput);
  inputArray.forEach((input, i) => {
    if (!isMediaElement(input) && !isTensor3D(input) && !isTensor4D(input)) {
      if (typeof inputArgArray[i] === 'string') throw new Error(`toNetInput -${getIdxHint(i)} string passed, but could not resolve HTMLElement for element id ${inputArgArray[i]}`);
      throw new Error(`toNetInput -${getIdxHint(i)} expected media to be of type HTMLImageElement | HTMLVideoElement | HTMLCanvasElement | tf.Tensor3D, or to be an element id`);
    }
    if (isTensor4D(input)) {
      // if tf.Tensor4D is passed in the input array, the batch size has to be 1
      const batchSize = input.shape[0];
      if (batchSize !== 1) throw new Error(`toNetInput -${getIdxHint(i)} tf.Tensor4D with batchSize ${batchSize} passed, but not supported in input array`);
    }
  });
  // wait for all media elements being loaded
  await Promise.all(inputArray.map((input) => isMediaElement(input) && awaitMediaLoaded(input)));
  return new NetInput(inputArray, Array.isArray(inputs));
}