face-api/src/tinyYolov2/extractParams.ts

import * as tf from '../../dist/tfjs.esm.js';

import { extractConvParamsFactory } from '../common/index';
import { extractSeparableConvParamsFactory } from '../common/extractSeparableConvParamsFactory';
import { extractWeightsFactory } from '../common/extractWeightsFactory';
import { ExtractWeightsFunction, ParamMapping } from '../common/types';
import { TinyYolov2Config } from './config';
import { BatchNorm, ConvWithBatchNorm, TinyYolov2NetParams } from './types';

function extractorsFactory(extractWeights: ExtractWeightsFunction, paramMappings: ParamMapping[]) {

  const extractConvParams = extractConvParamsFactory(extractWeights, paramMappings)

  function extractBatchNormParams(size: number, mappedPrefix: string): BatchNorm {

    const sub = tf.tensor1d(extractWeights(size))
    const truediv = tf.tensor1d(extractWeights(size))

    paramMappings.push(
      { paramPath: `${mappedPrefix}/sub` },
      { paramPath: `${mappedPrefix}/truediv` }
    )

    return { sub, truediv }
  }

  function extractConvWithBatchNormParams(channelsIn: number, channelsOut: number, mappedPrefix: string): ConvWithBatchNorm {

    const conv = extractConvParams(channelsIn, channelsOut, 3, `${mappedPrefix}/conv`)
    const bn = extractBatchNormParams(channelsOut, `${mappedPrefix}/bn`)

    return { conv, bn }
  }
  const extractSeparableConvParams = extractSeparableConvParamsFactory(extractWeights, paramMappings)

  return {
    extractConvParams,
    extractConvWithBatchNormParams,
    extractSeparableConvParams
  }

}

export function extractParams(
  weights: Float32Array,
  config: TinyYolov2Config,
  boxEncodingSize: number,
  filterSizes: number[]
): { params: TinyYolov2NetParams, paramMappings: ParamMapping[] } {

  const {
    extractWeights,
    getRemainingWeights
  } = extractWeightsFactory(weights)

  const paramMappings: ParamMapping[] = []

  const {
    extractConvParams,
    extractConvWithBatchNormParams,
    extractSeparableConvParams
  } = extractorsFactory(extractWeights, paramMappings)

  let params: TinyYolov2NetParams

  if (config.withSeparableConvs) {
    const [s0, s1, s2, s3, s4, s5, s6, s7, s8] = filterSizes

    const conv0 = config.isFirstLayerConv2d
      ? extractConvParams(s0, s1, 3, 'conv0')
      : extractSeparableConvParams(s0, s1, 'conv0')
    const conv1 = extractSeparableConvParams(s1, s2, 'conv1')
    const conv2 = extractSeparableConvParams(s2, s3, 'conv2')
    const conv3 = extractSeparableConvParams(s3, s4, 'conv3')
    const conv4 = extractSeparableConvParams(s4, s5, 'conv4')
    const conv5 = extractSeparableConvParams(s5, s6, 'conv5')
    const conv6 = s7 ? extractSeparableConvParams(s6, s7, 'conv6') : undefined
    const conv7 = s8 ? extractSeparableConvParams(s7, s8, 'conv7') : undefined
    const conv8 = extractConvParams(s8 || s7 || s6, 5 * boxEncodingSize, 1, 'conv8')
    params = { conv0, conv1, conv2, conv3, conv4, conv5, conv6, conv7, conv8 }
  } else {
    const [s0, s1, s2, s3, s4, s5, s6, s7, s8] = filterSizes
    const conv0 = extractConvWithBatchNormParams(s0, s1, 'conv0',)
    const conv1 = extractConvWithBatchNormParams(s1, s2, 'conv1')
    const conv2 = extractConvWithBatchNormParams(s2, s3, 'conv2')
    const conv3 = extractConvWithBatchNormParams(s3, s4, 'conv3')
    const conv4 = extractConvWithBatchNormParams(s4, s5, 'conv4')
    const conv5 = extractConvWithBatchNormParams(s5, s6, 'conv5')
    const conv6 = extractConvWithBatchNormParams(s6, s7, 'conv6')
    const conv7 = extractConvWithBatchNormParams(s7, s8, 'conv7')
    const conv8 = extractConvParams(s8, 5 * boxEncodingSize, 1, 'conv8')
    params = { conv0, conv1, conv2, conv3, conv4, conv5, conv6, conv7, conv8 }
  }

  if (getRemainingWeights().length !== 0) {
    throw new Error(`weights remaing after extract: ${getRemainingWeights().length}`)
  }


  return { params, paramMappings }
}