MIME Type Registrations for 3rd Generation Partnership Project (3GPP) Multimedia files
updated by
- rfc-6381 — The 'Codecs' and 'Profiles' Parameters for "Bucket" Media Types
Extracted elements (14)
Separate MIME types are registered for audio-only (audio/3gpp) versus any content (video/3gpp) to allow correct content negotiation and identification when files are served over HTTP or included in multi-part documents, without requiring examination of file contents.
It is valid to serve an audio-only 3GPP file as video/3gpp; the video/3gpp type is valid for all 3GPP files regardless of content type.
The audio/3gpp and video/3gpp MIME types are used only for files; separate MIME types and RTP payload formats are used for real-time transfer (e.g., RFC 2429 for H.263 video, RFC 3267 for AMR audio).
Files identified by the MIME types defined in this document MUST contain a brand defined in a standard issued by 3GPP that can apply to 3GPP files, in their compatible brands list.
Files served under the audio/3gpp type MUST NOT contain any visual material, including 3GPP timed text which is considered visual material.
The file-type box MUST occur first in the file, and MUST contain a 3GPP brand in its compatible brands list. This applies to both audio/3gpp and video/3gpp files.
The type audio/3gpp MAY be used for files containing audio but no visual presentation. Serving audio-only files as video/3gpp is also valid.
3GPP files must be transmitted in a binary-safe encoding without CR/LF conversion or 7-bit stripping; base64 is specified as a suitable encoding for MIME transport.
The 3GP file format is based on the ISO Media File Format and contains an intrinsic file-type box that identifies specifications the file complies with via four-letter 'brands'. At the time of writing, supported codecs include H.263 or MPEG-4 video, AMR Narrow-band, AMR Wide-band speech, AAC audio, and 3GPP timed text.
Registers the MIME type audio/3gpp for 3GPP multimedia files containing audio but no visual presentation. The preferred file extension is .3gp and the Macintosh file type code is '3gpp'.
Registers the MIME type video/3gpp for all 3GPP multimedia files, including audio-only files. The preferred file extension is .3gp and the Macintosh file type code is '3gpp'.
3GPP files have an extensible structure, so future metadata fields or media formats could theoretically be defined to induce actions on recipients, presenting additional security risks not present in the current specification. There is no current provision for encryption, signing, or authentication.
Selected metadata fields may contain DRM or rights management information; alteration or removal of such data could constitute an offense under national agreements based on WIPO treaties.
The 3GPP file format currently has no provision for active elements such as scripts, limiting the attack surface, though malicious files could request excessively large picture sizes or high sampling-rate audio.