(registered 2018-07-30, last updated 2018-08-09)

MIME media type name: image

MIME subtype name: heif, heic

   The semantics of the subtypes are as follows:

   heif: High efficiency image file containing one or more image 
      items using any coding format

   heic: High efficiency image file conforming to the requirements 
      for the 'heic', 'heix', 'heim', or 'heis' brand (and hence 
      containing one or more HEVC coded image items). (A brand in the 
      file header identifies a specific profile of a more general 
      format.)

   The use of subtype values is constrained as follows: 

   The MIME subtype name may be 'heic' only if the file conforms to 
   the requirements of the 'heic', 'heix', 'heim', or 'heis' brand, 
   and contains at least one of those brands as a compatible brand. 
   The MIME subtype name may be 'heif' only if the file conforms to 
   the requirements of the 'mif1' brand, and contains that brand as a 
   compatible brand.

Required parameters: none

Optional parameters:

   profiles: Specified by RFC 6381 and its successors.

   codecs: Specified by RFC 6381 and its successors for files 
      conforming to specifications derived from ISO/IEC 14496-12. 
      Note that for HEVC, the format of a list item included in the 
      value of the codecs parameter is specified in ISO/IEC 14496-15.

   itemtypes: One or more comma-separated item descriptions. 

      Each item description corresponds to the type of one or more 
      image items included in the file, in any order. An item 
      description should be present for the primary item of the file 
      and may be present for other image items of the file. 

      Each item description starts with an item type string and is 
      followed by a plus-separated ('+') list of zero or more item 
      property strings. 

      An item type string starts with the four-character item_type 
      value of the item and may be followed by zero or more 
      dot-separated ('.') qualifiers specified below. The field 
      item_type is defined in ISO/IEC 14496-12.

      When the item type is a four-character code of a coded image, 
      it may be followed by a dot-separated ('.') value, as specified 
      for the codecs parameter of the ISO base media file format name 
      space in RFC 6381. For the item type 'hvc1', the value after 
      the '.' is the profile-tier-level value as specified in ISO/IEC 
      14496-15.

      When the item type is a four-character code of a derived image 
      item, it may be followed by a dot-separated ('.') pixel count 
      value that is the positive decimal integer indicating the 
      number of pixels that is required for the input images of the 
      derived image item and the reconstructed image itself. For the 
      item type 'hvc1', the pixel count value must be present for an 
      item description, when that pixel count value is greater than 
      twice the largest pixel count inferred from the 
      profile-tier-level value of any coded image of the same item 
      description list.

      An item property string consists of the box-type of an item 
      property marked as essential. The list of the item property 
      strings must indicate the entire set of item properties that 
      are marked as essential. The item property strings must appear 
      in the order they are associated with the image item in the 
      file.

   lhevcptl: For multi-layer image items, specifies the decoding 
      capabilities required for different combinations of layers and 
      temporal sub-layers; the syntax and semantics are specific to 
      HEVC and are formally specified by the lhevcptl optional MIME 
      parameter in ISO/IEC 14496-15 for the L-HEVC sample entry 
      types. Informatively, the syntax is BLInternal, ListItem1(, 
      ListItemN)*, where 

      BLInternal is 0 or 1; 
      each Listitem has the structure 
         OlsIdx.MaxTid.ProfileTierLevel1(.ProfileTierLevelN)*
      and
      OlsIdx and MaxTid are integers
      ProfileTierLevelX is the substring specified for any HEVC 
         sample-entry for the codecs parameter

   dependencies: a list of comma-separated URLs (see RFC 3986) from 
      the DataReferenceBoxes in the top-level MetaBox and all tracks. 
      The DataReferenceBoxes indicating a reference to the same file 
      as the container file must not be listed. The URLs should be 
      relative whenever possible. Note that the URLs are often, but 
      not required to be, relative, and that some characters in URLs 
      may require escaping in some situations. DataReferenceBox and 
      MetaBox are specified in ISO/IEC 14496-12.

Encoding considerations: as for video/mp4

Security considerations: See section 4 of RFC 4337 and section 7 of 
   RFC 6381. This format does not supply integrity or confidentiality 
   protection and so they are applied externally when needed. The 
   security considerations of URLs are discussed in RFC 3986.

Interoperability considerations: Interoperably deployed in reference 
   code available from ISO, Javascript code from Nokia labs, in 
   open-source in MP4Box and various other implementations.

Published specification: ISO/IEC 23008-12, available as a Publicly 
   Available Standard at 
   http://standards.iso.org/ittf/PubliclyAvailableStandards/index.html

Applications: Multimedia, Imaging, Pictures

Fragment identifier considerations: Fragment identifiers are 
   specified in Annex L of ISO/IEC 14496-12, available as a Publicly 
   Available Standard at 
   http://standards.iso.org/ittf/PubliclyAvailableStandards/index.html

Additional information:

   Magic number(s): none
   File extension(s): heif (for subtype heif), heic (for subtype 
      heic), hif (for subtypes heif and heic)
   Macintosh File Type Code(s): None

Person to contact for info: David Singer, singer&apple.com

Intended usage: Common

Author/Change controller: David Singer, ISO/IEC/JTC1/SC29/WG11 file 
   format chair