{
  "patent_number": "US RE47935",
  "country": "US",
  "title": "How Digital Audio Compression Saves Space by Copying Frequencies",
  "original_title": "USRE47935E1 - Encoding device and decoding device",
  "summary": "A method for shrinking audio files by only saving the lower-pitched sounds and using clever math to reconstruct the higher-pitched sounds from them.",
  "what_it_does": "This patent describes a way to compress digital audio by splitting a sound signal into two parts: a lower frequency range that is saved in full, and a higher frequency range that is reconstructed. Instead of saving all the high-frequency data, the encoder identifies a specific 'partial spectrum' from the lower range and copies it to represent the higher range. It then sends a few parameters—like a gain factor to adjust volume and a toggle to invert the signal—to tell the decoder exactly how to transform that copied piece to sound like the original high frequencies. This significantly reduces the amount of data needed to transmit or store high-quality audio.",
  "what_it_does_not_cover": [
    "Does not cover audio compression that saves the entire high-frequency spectrum without using frequency copying or band extension.",
    "Does not cover methods that do not use the specific third parameter for frequency domain inversion of the copied spectrum.",
    "Does not cover the physical hardware of microphones or speakers used to capture or play back the audio."
  ],
  "filed": "2017-07-27",
  "granted": "2020-04-07",
  "expires": null,
  "status": "active",
  "holder": "Dolby International AB",
  "holder_url": "https://patentbrief.org/company/dolby-international-ab",
  "inventors": [
    {
      "name": "Kosuke Nishio",
      "url": "https://patentbrief.org/inventor/kosuke-nishio"
    },
    {
      "name": "Takeshi Norimatsu",
      "url": "https://patentbrief.org/inventor/takeshi-norimatsu"
    },
    {
      "name": "Naoya Tanaka",
      "url": "https://patentbrief.org/inventor/naoya-tanaka"
    },
    {
      "name": "Mineo Tsushima",
      "url": "https://patentbrief.org/inventor/mineo-tsushima"
    }
  ],
  "times_cited": 0,
  "tags": [
    "telecommunications",
    "consumer_electronics",
    "software"
  ],
  "abstract": "An encoding device (200) includes an MDCT unit (202) that transforms an input signal in a time domain into a frequency spectrum including a lower frequency spectrum, a BWE encoding unit (204) that generates extension data which specifies a higher frequency spectrum at a higher frequency than the lower frequency spectrum, and an encoded data stream generating unit (205) that encodes to output the lower frequency spectrum obtained by the MDCT unit (202) and the extension data obtained by the BWE encoding unit (204). The BWE encoding unit (204) generates as the extension data (i) a first parameter which specifies a lower subband which is to be copied as the higher frequency spectrum from among a plurality of the lower subbands which form the lower frequency spectrum obtained by the MDCT unit (202) and (ii) a second parameter which specifies a gain of the lower subband after being copied.",
  "url": "https://patentbrief.org/patent/us/RE47935/google-chrome-browser",
  "markdown_url": "https://patentbrief.org/patent/us/RE47935/google-chrome-browser/md",
  "google_patents_url": "https://patents.google.com/patent/USRE47935",
  "relatedPatents": []
}