Sustainability of Digital Formats
 Planning for Library of Congress Collections

Introduction | Sustainability Factors | Content Categories | Format Descriptions | Contact
Format Description Categories >> Browse Alphabetical List

QuickTime File Format

>> Back
Table of Contents
Format Description Properties Explanation of format description terms

Identification and description Explanation of format description terms

Full name QuickTime File Format
Description

File format that wraps video, audio, and other bitstreams. This description is concerned with QuickTime as a video wrapper (generally with a synchronized audio stream), called "movie" files by Apple, and as a sound wrapper, especially as used by Apple's iTunes music service. QuickTime also wraps still images (QuickTime Image Files), animations not recorded as video, virtual reality, etc., and these are not discussed at this site, with the exception of SWF_7 and SWF_8, the Flash SWF File Format (versions 7 and 8).

Specialists describe Quicktime atoms as the format's fundamental building blocks. The MultimediaWiki reports, "Atoms are chunks of data in that comprise a Quicktime file. Sometimes they contain data and sometimes they contain other atoms. . . . An atom consists of a size, a type, and a data payload."

As of February 2012, two versions of the file format specification were offered by Apple: the "classic" from 2001 and a newer version, as updated in 2012. Various sources, including the Wikipedia QuickTime article (consulted February 2, 2012), name a number of versions of Quicktime, from 1991 to the present, but these seem to be references to the Quicktime production or playback software rather than the file wrapper per se.

Production phase Typically a final state format for enduser delivery; sometimes a middle-state format, e.g., the source when producing lower-resolution streaming versions.
Relationship to other formats
    Has subtype QTV_Apple, QuickTime Video, Apple Codec
    Has subtype QTV_Cinepak, QuickTime Video, Cinepak Codec
    Has subtype QTV_DV, QuickTime Video, DV Digital Video
    Has subtype QTV_MPEG, QuickTime Video, MPEG Codec
    Has subtype QTV_MJPEG, QuickTime Video, Motion JPEG Codec
    Has subtype QTV_MP4_V, QuickTime Video, MPEG-4 Visual Coding
    Has subtype QTV_MP4_AVC, QuickTime Video, MPEG-4 Advanced Video Coding
    Has subtype QTV_Sorenson, QuickTime Video, Sorenson Codec
    Has subtype QTV_SWF, QuickTime Video with SWF Flash
    Has subtype QT_210, Quicktime File Format with V210 Video Encoding. Uncompressed 10-bit 4:2:2 Picture.
    Has subtype QT_UYVY, Quicktime File Format with UYVY (2vuy) Video Encoding. Uncompressed 8-bit 4:2:2 Picture.
    Has subtype QT_YUY2, Quicktime File Format with YUY2 (yuv2) Video Encoding. Uncompressed 8-bit 4:2:2 Picture.
    Has subtype QuickTime movie variants defined by several other video codecs not documented at this time.
    Has subtype QTA_AAC, QuickTime Audio, AAC Codec
    Has subtype QTA_MP3, QuickTime Audio, MP3 Codec
    Has subtype QuickTime sound variants defined by other audio codecs, including uncompressed and lossless audio, not documented at this time.
    Affinity to QuickTime Image File Format, not documented at this time.

Local use Explanation of format description terms

LC experience or existing holdings Limited to video: American Memory has produced QuickTime files for web service since the mid-1990s, typically using the Cinepak codec at 10 fps and 160x120 pixels. For the special videos associated with the Dance Instruction Manuals collection, a second set of higher-resolution QuickTime files was produced, using the Sorenson codec at 15 fps and 320x240 pixels. The audio stream in both types employs IMA (Interactive Multimedia Association) 4:1 compression, based on PCM sampling at 22 kHz.

In 2004, the Motion Picture, Broadcasting, and Recorded Sound Division collected a series of nine "enhanced" QuickTime movies produced by BMW (formerly available at http://usa.bmwfilms.com/), with the main video object in the form of QTV_Sorenson.
LC preference Regarding compressed video, bitstreams in MPEG-2 or -4 formats. Regarding uncompressed or losslessly compressed video, MXF_OP1a_JP2_LL is preferred by specialists at the Library's Packard Campus for Audio-Visual Conservation.

Sustainability factors Explanation of format description terms

Disclosure Fully documented. Proprietary format developed by Apple Computer, Inc.
    Documentation QuickTime File Format Specification; both the "classic" (2001) and updated-through-2012 versions link from this menu page.
Adoption Widely adopted.
    Licensing and patents Licensing by Apple appears to be limited to the software and other technology elements.
Transparency The file format is relatively transparent. See information on the codecs contained in QuickTime files: Cinepak, Sorenson_3, MPEG-1, MJPEG, LPCM, AAC, and MP3.
Self-documentation Technical metadata is in the headers for the atoms and container atoms that comprise a QuickTime file and also in the locations in the file. Descriptive ("bibliographic") metadata may be entered within the following annotations: "Album", "Artist", "Author", "Comment", "Copyright", "Creation Date", "Description", "Director", "Disclaimer", "Full Name", "Host Computer", "Information", "Make", "Model", "Original Format", "Original Source", "Performers", "Producer", "Product", "Software", "Special Playback Requirements", "Warning", and "Writer."
External dependencies None
Technical protection considerations QuickTime files may be structured to require endusers to enter a media key before the file can be played. Newsgroup traffic about iTunes includes a statement from a commentator that reports, "iTunes uses a DRM system that prevents files to be played on more than 3 platforms and only the iTunes player can cope with that DRM system."

Quality and functionality factors Explanation of format description terms

Still Image
Normal rendering Good support.
Clarity (high image resolution) Moderate to good, depending upon the type and level of compression, and the encoder used. See QTV_Apple, QTV_Cinepak, QTV_Sorenson, QTV_MPEG, and QTV_MJPEG. Extent of use of uncompressed video bitstream unknown.
Functionality beyond normal rendering Supports various features, e.g., sprites, animation, virtual reality, etc. See Notes below for information about multiple timecodes.
Sound
Normal rendering Good support
Fidelity (high audio resolution) Depends upon encoding; may be used with lossy encodings like MP3 (and many others) and uncompressed audio like LPCM, although this is limited to 16 bit word length. See also QTA_AAC and QTA_MP3.
Multiple channels Not investigated for this description at this time.
Support for user-defined sounds, samples, and patches Not investigated for this description at this time.
Functionality beyond normal rendering Not investigated for this description at this time.

File type signifiers Explanation of format description terms

Tag Value Note
Filename extension mov
qt
For movie files.
Filename extension m4p
mp3
For sound files. The m4p extension is for QuickTime files containing AAC bitstreams purchased from iTunes and protected by a digital rights management scheme. Bookmarkable AAC files may carry the extension m4b. [The mp3 extension is for QuickTime sound files containing MP3 bitstreams; extent of protection unknown at this writing.]
Filename extension qtif
qti
qif
For QuickTime Image Files; from The File Extension Source.
Internet Media Type video/quicktime
video/x-quicktime
image/mov
For movie files. From From http://www.iana.org/assignments/media-types/video/quicktime and The File Extension Source.
Internet Media Type Not found.  Comments welcome.  For sound files; no MIME type found at this writing.
Internet Media Type image/x-quicktime
For image files; selected from The File Extension Source.
Magic numbers Hex: xx xx xx xx 6D 6F 6F 76
ASCII: ....moov
From Gary Kessler's File Signatures Table.
Mac OS file type See note.  Video type tag (QuickTime). Four-character codes that vary according to the video codec selected; see the QuickTime File Format specification (2001), p. 92 or p. 96.1
Uniform Type Identifier (Mac OS) See note.  Audio type tag (QuickTime). Four-character codes that vary according to the audio codec selected; see the QuickTime File Format specification (2001), pp. 102-03 or pp. 107-9.1

Notes Explanation of format description terms

General The documentation and retention of multiple timecodes may be of interest to those producing complete or authentic copies of a source item that may include multiple timecodes, e.g., LTC, VITC, or ANC. In historical recordings these are often not synchronized and may reveal aspects of how a given video program had been produced. Quicktime permits users to make as many timecode tracks as they wish, but experts report that this can inhibit interoperability and some tracks may not be properly read. Timecode data is stored in Quicktime's tmcd atom, one set of timecode data per tmcd atom. The timecode track in Quicktime has a label that many systems use to note an identifier of the source tape; for example, it stores the data of the "Reel" field in the Final Cut software application.
History Introduced in 1991; structured for use in Windows, 1994; in the mid-to-late 1990s, the format influenced the shape of MPEG-4. See the Wikipedia article on QuickTime (as consulted February 2012) for excellent detail.

Format specifications Explanation of format description terms


Useful references

URLs

Books, articles, etc.

1There seem to have been at least two printings of the specification carrying the same date. These were not systematically compared by the compiler of this Web page. Pagination varies between these two printings.


Last Updated: Thursday, 07-Nov-2013 07:55:21 EST