Sustainability of Digital Formats: Planning for Library of Congress Collections
Sustainability of Digital Formats: Planning for Library of Congress Collections |
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| Introduction | Sustainability Factors | Content Categories | Format Descriptions | Contact | |
| Full name | Sorenson Video Codec, Version 3 |
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| Description |
Bitstream encoding for video developed by Sorenson Media, Inc. The compiler of this description is uncertain about Sorenson's version numbers. Sorenson Media promotional information for version 4.5 of the Squeeze software application, consulted in February 2007, listed a number of possible output formats, including MPEG-, -2, and -4, and Flash Output (Spark). Spark may be the successor to the Sorenson codec, version 3, initially described at this Web site in 2004; comments welcome. The matter of versioning may account for the fact that the Wikipedia article on the Sorenson codec associates the codec with both ITU-T H.263 (see MPEG-4_V) and H.264 (see MPEG-4_AVC). Macromedia (now Adobe) literature states that the FLV/SWF variant of Sorenson is related to H.263. The SIGGRAPH education page states that the codec uses "advanced vector quantization with motion compensation," and that the Developer Edition of the Sorenson codec offers variable bitrate encoding, temporal scalability (sensitivity to the ability of the playing machine to process data), and the automatic determination of new keyframes (frames that contain all image information without reference to predictive or bidirectional frames that require adjacent frames for decoding). |
| Production phase | Generally used as an end-user delivery format. |
| Relationship to other formats | |
| Used by | QTV_Sorenson, QuickTime Video, Sorenson Codec |
| Used by | SWF_7, Macromedia Flash SWF File Format, Version 7 |
| Used by | SWF_8, Macromedia Flash SWF File Format, Version 8 |
| Used by | FLV, Macromedia Flash FLV File Format |
| Used by | Other formats, not documented at this time. |
| LC experience or existing holdings | American Memory produced QTV_Sorenson (QuickTime, Sorenson codec) for the Dance Instruction Manuals collection, where they offered endusers larger picture size and higher resolution than provided by QTV_Cinepak (QuickTime, Cinepak codec) files. The QTV_Sorenson files are encoded at 15 fps and 320x240 pixels; the audio stream employs IMA (Interactive Multimedia Association) 4:1 compression, based on PCM sampling at 22 kHz. |
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| LC preference | See QuickTime |
| Disclosure | Proprietary standard developed by Sorenson Media, Inc. |
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| Documentation | Not a specification but modest, helpful documentation is provided by a SIGGRAPH education page. |
| Adoption | Apparently widespread. |
| Licensing and patents | Codecs and software may be licensed from Sorenson Media, Inc. |
| Transparency | Depends upon algorithms and tools to read; will require sophistication to build tools. |
| Self-documentation | Not applicable; provided by wrapper formats. |
| External dependencies | None. |
| Technical protection considerations | The SIGGRAPH education page states that Sorenson encoding software offers watermarking and media keys that permit producers to limit viewing to users who have the required key. These or additional protections may also be provided by wrapper formats. |
| Moving Image | |
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| Normal rendering | Not applicable |
| Clarity (high image resolution) | Moderate, given this is a compression format. |
| Functionality beyond normal rendering | Not applicable |
| Tag | Value | Note |
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| Filename extension | Not applicable. | |
| Internet Media Type | Not applicable. | |
| Magic numbers | Not applicable. |
| General | |
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| History |
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