static estimateAvifSizeFromWebPAndJpegEstimates(otherFormatSizes) {
    if (!otherFormatSizes.jpegSize || !otherFormatSizes.webpSize) return undefined;

    // AVIF saves at least ~50% on JPEG, ~20% on WebP at low quality.
    // http://downloads.aomedia.org/assets/pdf/symposium-2019/slides/CyrilConcolato_Netflix-AVIF-AOM-Research-Symposium-2019.pdf
    // https://jakearchibald.com/2020/avif-has-landed/
    // https://www.finally.agency/blog/what-is-avif-image-format
    // See https://github.com/GoogleChrome/lighthouse/issues/12295#issue-840261460 for more.
    const estimateFromJpeg = otherFormatSizes.jpegSize * 5 / 10;
    const estimateFromWebp = otherFormatSizes.webpSize * 8 / 10;
    return estimateFromJpeg / 2 + estimateFromWebp / 2;
  }
@param {{jpegSize: number | undefined, webpSize: number | undefined}} otherFormatSizes
@return {number|undefined}