Thor (video codec)

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Developed byCisco Systems
Type of formatVideo codec
Extended toNETVC, AV1
Open format?Yes
Free format?Yes

Thor is a royalty-free video codec under development by Cisco Systems. The specifications of Thor were available in various Internet Drafts.[1]

On July 22, 2015, Thor was presented to the IETF as a candidate for their NETVC video standard.[2] Thor uses some Cisco elements that are also used by HEVC.[3] As part of the NETVC work, the Constrained Low-Pass Filter (CLPF) and motion compensation techniques used in Thor were tested in conjunction with the lapped transform coding techniques from the Daala codec.[4]

On September 1, 2015, Cisco announced that the Alliance for Open Media would use elements of Thor to develop a royalty free video format, AOMedia Video 1.[5][6][7]

According to Steinar Midtskogen, a principal Thor developer and AV1 contributor, Thor is in good shape for real-time CPU encoding (as of NETVC meeting 101, March 19, 2018), in strong contrast to AV1 at the same time.[8] Thor development had stalled for the finalization of AV1, but Midtskogen envisaged further Thor development by merging the Daala entropy coder and adding more tools for screen content.[9]


  1. ^ A. Fuldseth; G. Bjontegaard; S. Midtskogen; T. Davies; M. Zanaty (2016-03-18). "Thor Video Codec". IETF. Retrieved 2016-06-14.
  2. ^ "NETVC IETF 93". Internet Engineering Task Force. Retrieved 2015-08-11.
  3. ^ "Thor: High Efficiency, Moderate Complexity Video Codec using only RF IPR" (PDF). Internet Engineering Task Force. Retrieved 2015-08-11.
  4. ^ NETVC Hackathon Results IETF 93 (Prague) (PDF)
  5. ^ "New open standard for Ultra High Definition video will enable enhanced video playback". Alliance for Open Media. 2015-09-01. Archived from the original on 2015-09-03. Retrieved 2015-09-01.
  6. ^ Stephen Shankland (2015-09-01). "Tech giants join forces to hasten high-quality online video". CNET. Retrieved 2015-09-01.
  7. ^ Zimmerman, Steven (15 May 2017). "Google's Royalty-Free Answer to HEVC: A Look at AV1 and the Future of Video Codecs". XDA Developers. Archived from the original on 14 June 2017. Retrieved 10 June 2017.
  8. ^ IETF101-NETVC-20180319-1550. IETF - Internet Engineering Task Force. 19 March 2018. Retrieved 23 May 2018 – via YouTube. It's certainly possible to get real-time encoding with Thor, that we know, but for AV1, it's not proven yet.
  9. ^ "Thor update and AV1 comparisons". IETF. Retrieved 23 May 2018.

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