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 | RealAudio, Version 10 |
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| Description | Proprietary file format for streaming audio. Provides for four different codecs; see Relationships to Other Formats, below. |
| Production phase | Generally a final-state (end-user delivery) format. |
| Relationship to other formats | |
| Has subtype | RealAudio_RA, RealAudio, RealAudio Codec |
| Has subtype | RealAudio_AAC, RealAudio, AAC Codec |
| Has subtype | RealAudio_LL, RealAudio, Lossless Codec |
| Has subtype | RealAudio_MC, RealAudio, Multichannel Codec |
| May contain | RealAudio codec, not separately documented |
| May contain | AAC, Advanced Audio Coding (MPEG-2). (codec) |
| May contain | RealAudio lossless codec, not separately documented |
| May contain | RealAudio multichannel codec, not separately documented |
| LC experience or existing holdings | The Library of Congress has a small amount of RealAudio files in its collections. |
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| LC preference | See the Library of Congress Recommended Formats Statement for format preferences for audio works. |
| Disclosure | Proprietary format with little public documentation, although licenses for certain classes of developers may provide access to source code. |
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| Documentation | Limited documentation |
| Adoption | Widely adopted for streaming web content and other online applications, starting in the mid-1990s. As of March 2012, the Wikipedia page for RealAudio notes that although used widely by radio stations for streaming audio in the past, use has become less common in recent years. In particular, the BBC dropped use from its primary website in 2009, and from the BBC World Service in 2011. |
| Licensing and patents | Licensing for RealAudio and RealVideo, and for related production and delivery tools, is described at https://helixcommunity.org/content/licenses, an entity of RealNetworks, Inc. Licensing includes open source and research and development arrangements that provide access to the source code for the codecs. |
| Transparency | Depends upon algorithms and tools to read; will require sophistication and documentation to build tools. |
| Self-documentation | Embedded bibliographic or descriptive metadata is included in online examples, e.g., title, artist, genre. This writer could not find documentation as of April 2004; RealAudio may share metadata structure with RealVideo. |
| External dependencies | Playback of surround sound requires multiple loudspeakers. |
| Technical protection considerations | RealAudio likely to share technical protection devices with RealVideo. |
| Moving Image | |
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| Normal rendering | Good support. |
| Functionality beyond normal rendering | A sequence of Web pages can be synchronized for display with the playback of streaming media in a RealMedia player when HTML-page URLs are embedded in a RealMedia clip. |
| Tag | Value | Note |
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| Filename extension | rm |
For RealMedia file. See HomeRecording.com for discussion of audio-only .rm vs .ra files. |
| Filename extension | ra |
Note that streaming applications require an associated ram (RealMedia Metafile) file. |
| Internet Media Type | application/vnd.rn-realmedia |
From RealNetworks web page; this MIME type was associated with extension rm. No examples found in IANA MIME Media Types. |
| Internet Media Type | audio/vnd.rn-realaudio |
From RealNetworks web page; this MIME type was associated with extension ra and ram. No examples found in IANA MIME Media Types. |
| Magic numbers | Hex: 2E 52 4D 46 ASCII: .RMF |
From Gary Kessler's File Signatures Table. |
| Magic numbers | Hex: 2E 52 4D 46 00 00 00 12 00 ASCII: .RMF |
From The File Extension Source. |
| Pronom PUID | See note. | PRONOM has no corresponding entry as of July 2022. |
| Wikidata Title ID | Q201093 |
See https://www.wikidata.org/wiki/Q201093.Note that Wikidata does not specify versions. |
| General | |
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| History |
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