Sustainability of Digital Formats
Planning for Library of Congress Collections
Sustainability of Digital Formats
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| Introduction | Sustainability Factors | Content Categories | Format Descriptions | Contact | |
| Full name | DV, DVCAM, DVCPRO (family of related formats) |
| Description | For the purposes of this Web site, this family of related formats is described together, emphasizing the underlying encoding as it may be stored in media-independent files. The DV video format, however, was developed in the early 1990s as a media-dependent videocassette format. DV video signals are compressed using discrete cosine transforms (DCT) within each frame, like the the approach used with JPEG_DCT. DV does not use frame-to-frame temporal encoding like that employed by MPEG-2 and other MPEG formats. In the years after its introduction, similar but higher quality elaborations were offered by SONY (DVCAM) and Panasonic (DVCPRO, DVCPRO-50, DVCPRO HD), and these have found their place in professional television production. DV signals are formatted for transfer between devices in 80-byte blocks referred to as DV-DIF data (DV Digital Interface Format), and these DV-DIF blocks can be stored as files in raw form (.dv or .dif extension) or wrapped in such file formats as AVI, QuickTime, and MXF. Comments on this format description are welcome. |
| Production phase | Generally a initial-state or middle-state format. |
| Relationship to other formats | |
| Contains | DV-DIF, Digital Video Digital Interface Format |
| LC experience or existing holdings | Experience and holdings of DV in file form not investigated at this time. Videocassettes of DV, DVCAM, and DVCPRO formats are represented in the collections of the Motion Picture, Broadcasting and Recorded Sound Division. |
| LC preference | None established |
| Disclosure | Open standards. Initial specification developed by a consortium of ten companies and standardized by the International Electrotechnical Commission (IEC); elaborations developed by SONY and Panasonic and standardized by the Society of Motion Picture and Television Engineers (SMPTE). |
| Documentation | Using shorthand borrowed from SMPTE specification 383M (Material Exchange Format (MXF) -- Mapping DV-DIF Data to the MXF Generic Container, p.2), the documentation for the three compression specifications is as follows. Full citations are provided in Format specifications below. Comments on this information are welcome.
• IEC DV as specified in IEC 61834-2 (operating at 525/60i and 625/50i) [published 1998] • DV-based as specified in SMPTE 314M (525/60i and 625/50i), covers both DVCAM and DVCPRO [published 1999] • DV-based as specified in SMPTE 370M (1080/60i, 1080/50i, and 720/60p), covers DVCPRO HD [published 2002] Additional specifications that pertain to the broad class of DV formats are listed in Format specifications below. |
| Adoption | For videocassettes, DV, DVCAM, and DVCPRO are widely adopted. DV incorporated in files is also widely adopted. Public television station WGBH (Boston) reports that DVCPRO-50 files are regularly used for program masters. Apple ships the DVCPRO-50 and -100 codecs with their Final Cut Pro editing product. The extent of file-based adoption of DVCAM is not known to the compiler of this page; comments are welcome. |
| Licensing and patent claims | None identified. |
| Transparency | Depends upon algorithms and tools to read; will require sophistication to build tools. |
| Self-documentation | Pertains to the file format that wraps DV-DIF. |
| External dependencies | None for files; many DV, DVCAM, and DVCPRO content items are recorded on videocassettes specified for those formats |
| Technical protection considerations | Pertains to the file format that wraps DV-DIF. |
| Video elements | ||
| Normal rendering | Good support. | |
| Clarity (support for high image resolution) | • DV, DVCAM, and DVCPRO: moderate to very good, given that sampling is limited to 4:1:1 (NTSC; 4:2:0 for some PAL signals). These three formats carry 8 bits for luma and chroma channels and have a moderate data rate of 25 MB/s. • DVCPRO-50: excellent, the sampling is 4:2:2 with a higher data rate of 50 MB/s. [Also 8-bits? Comments welcome.] • DVCPRO HD: excellent, the sampling is 4:2:2 with a data rate of 100 MB/s. [8 or 10-bits? Comments welcome.] | |
| Functionality beyond normal video rendering | Not investigated at this time. | |
| Sound elements | ||
| Normal rendering | Not investigated at this time. Adam Wilt discusses the impact of locked and unlocked audio on the synchronization of picture and sound. Locked audio is preferred and offered by DVCAM and DVCPRO. | |
| Fidelity (support for high audio resolution) | Good to excellent. PCM audio with sampling up to 48 kHz and word length up to 20 bits. | |
| Support for multiple sound channels | Eight channels supported. | |
| Functionality beyond normal rendering | Not investigated at this time. |
| Tag type | Value | Note |
| Filename Extension | Not applicable | See DV-DIF |
| Internet Media Type | Not applicable | See DV-DIF |
| Magic numbers | Not applicable |
| General | |
| History | Adam Wilt's DV, DVCAM, DVCPRO Formats-FAQ-technical (http://www.adamwilt.com/DV-FAQ-tech.html) and Internet Request for Comment (RFC) 3189, RTP Payload Format for DV (IEC 61834) Video, are the sources for much of the following: There are two kinds of DV, one for consumer use and the other for professional. In 1992, AVC-Matsushita (now Panasonic) disseminated a Blue Book pertaining to the format. In 1995, SONY introduced the DV camcorder. In 1998, the original "DV" specification (based on the Blue Book), oriented toward consumer-use digital VCRs, was published as IEC 61834; part 2 specifies the video coding as well as many other elements. The specifications for professional DV were published as SMPTE 306M (1998) and 314M (1999); these two encoding formats are based on consumer DV and used in SMPTE D-7 and D-9 video systems. By and large, the preceding developments were framed in terms of videocassette media. The RTP payload format specified in RFC 3189 (2002) supports IEC 61834 consumer DV and professional SMPTE 306M and 314M (DV-Based) formats. For several years, many DV devices have provided interfaces such as IEEE 1394 (Firewire) in order to facilitate the movement of video streams into computer files. Increasing interest in media-less handing of the bitstream has led to developments like Panasonic's P2 solid state memory format cards, featured at the National Association of Broadcasters (NAB) trade show in 2005. |
URLs
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• IEC 61834-1. Recording - Helical-scan digital video cassette recording system using 6,35 mm magnetic tape for consumer use (525-60, 625-50, 1125-60 and 1250-50 systems) - Part 1: General specifications
• IEC 61834-2. Recording - Helical-scan digital video cassette recording system using 6.35 mm magnetic tape for consumer use (525-60, 625-50, 1125-60 and 1250-50 systems) - Part 2: SD format for 525-60 and 625-50 systems
• SMPTE 306M-2002. Television Digital Recording - 6.35-mm Type D-7 Component Format - Video Compression at 25 Mb/s - 525/60 and 625/50
• SMPTE 307M-2002. Television Digital Recording - 6.35-mm Type D-7 Component Format - Tape Cassette
• SMPTE 314M-1999. Television - Data Structure for DV-Based Audio, Data and Compressed Video - 25 and 50 Mb/s
• SMPTE 321M-2002. Television - Data Stream Format for the Exchange of DV-Based Audio, Data and Compressed Video Over
a Serial Data Transport Interface
• SMPTE 370M-2002. Television - Data Structure for DV-Based Audio, Data and Compressed Video at 100 Mb/s 1080/60i,
1080/50i, 720/60p
• SMPTE 371M-2002. Television - 6.35-mm Type D-12 Component Format - Digital Recording at 100 Mb/s 1080/60i, 1080/50i, 720/60p
URLs
• The DV, DVCAM, DVCPRO Formats-FAQ-technical (www.adamwilt.com/DV-FAQ-tech.html)
• The DV, DVCAM, DVCPRO Formats-Technical Details (http://www.adamwilt.com/DV-tech.html)
• RTP Payload Format for DV (IEC 61834) Video [RFC 3189] (http://www.faqs.org/rfcs/rfc3189.html)
• Do DV Formats Mystify You? (defunct article held by the Internet Archive; http://web.archive.org/web/20040423060434/http://www.wdva.org/dvedge/equipmentcont.php)
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