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Still Image Formats
| Content | Preference | Format | Format Use | Notes | |
|---|---|---|---|---|---|
| Preservation | Delivery | ||||
| Still Image | Preferred (in order of preference) | TIFF uncompressed in any color space supported by TIFF | X | TIFF has been commonly used at Harvard for digital master images, and is considered an archival format suitable for long-term preservation. For more information about the TIFF format see Adobe's TIFF resources | |
| JPEG 2000 JP2 profile with lossless compression | X | X | Some projects depositing content into the DRS have chosen to use JPEG 2000 for digital master images instead of TIFF. JPEG 2000 can offer storage savings - file sizes tend to be smaller and there is an opportunity to use the same file as the preservation and use copy. While JPEG 2000 is becoming more acceptable in the library community as a preservation format, there are still advantages to TIFF over JPEG 2000 for preservation. TIFF uncompressed is a simpler format internally and has more general tool support. For more information about JPEG 2000 see the JPEG 2000 website; rendered by Image Delivery Service (IDS) | ||
| TIFF with CCITT T.6 (Group 4) compression | X | ||||
| JPEG 2000 JP2 profile with lossy compression | X | X | Rendered by Image Delivery Service (IDS) | ||
| JPEG JFIF; TIFF with associated alpha component; TIFF with PackBits (lossless), LZW (lossless), Modified Huffman or Group 3 Fax compression | X | X | Rendered by Image Delivery Service (IDS) | ||
| GIF | X | X | Rendered by Image Delivery Service (IDS) | ||
| Accepted | JPEG (non-JFIF) | X | X | (suggested alternative: TIFF uncompressed or JPEG 2000 JP2 profile with lossless compression); rendered by Image Delivery Service (IDS) | |
| TIFF with JPEG (lossy) compression | X | (suggested alternative: TIFF uncompressed or JPEG 2000 JP2 profile with lossless compression) | |||
Video Formats
Harvard Library Media Preservation Services will provide reformatting services to produce these formats.*
| Content | Preference | Format | Format Use | Notes | |
|---|---|---|---|---|---|
| Preservation | Delivery | ||||
| Video | Preferred | Codec: JPEG 2000 Wrapper: QuickTime, MXF (MXF OP1a, OP1b operational patterns or AS-07) | X | Recommend lossless compression | |
| Codec: Uncompressed Wrapper: QuickTime | X | 8 bit or 10 bit | |||
| Codec: DV Wrapper: QuickTime | X | For digitized DV tape | |||
| Codec: MPEG-2 Wrapper: QuickTime | X | ||||
| Codec: H.264 Wrapper: QuickTime | X | Any of the 21 different profiles; delivered by Streaming Delivery Service (SDS) | |||
| Accepted | Codec: Avid DNxHD Wrapper: QuickTime, MXF (MXF OP1a, OP1b operational patterns or AS-07) | X | |||
| Codec: Apple ProRes Wrapper: QuickTime | X | ||||
Disk Image Formats
| Content | Preference | Format | Format Use | Notes | |
|---|---|---|---|---|---|
| Preservation | Delivery | ||||
| Disk Image | Preferred | RAW (IMG,DD) | X | Often disk image formats are split into smaller files that are stitched together in sequence, often in 2GB chunks. When this occurs, many systems use sequential file extension numbering to delineate the relationships, e.g., myimage.001, myimage.002, myimage.003; or yourimage.e01, yourimage.e02, yourimage.e03. When this occurs, it is imperative that original filenames AND extensions be preserved so that they can be re-instantiated upon delivery to an end user (otherwise it will not be possible to put the sequence back together in the proper order). | |
| ISO | X | There are possibilities that some ISO files are merely RAW files that contain ISO file systems within them. Some ISO files may be pure copies of ISO file systems. | |||
| BIN/CUE | X | Often disk image formats are split into smaller files that are stitched together in sequence, often in 2GB chunks. When this occurs, many systems use sequential file extension numbering to delineate the relationships, e.g., myimage.001, myimage.002, myimage.003; or yourimage.e01, yourimage.e02, yourimage.e03. When this occurs, it is imperitave that original filenames AND extensions be preserved so that they can be re-instantiated upon delivery to an end user (otherwise it will not be possible to put the sequence back together in the proper order). Only .BIN files (and sometimes .ISO files) include sidecare .CUE files. The .CUE files serve as metadata for understanding the type and composition of data stored in the .BIN (or .ISO) file. | |||
| EWF-E01 (EWCF-ASR02) | X | Often disk image formats are split into smaller files that are stitched together in sequence, often in 2GB chunks. When this occurs, many systems use sequential file extension numbering to delineate the relationships, e.g., myimage.001, myimage.002, myimage.003; or yourimage.e01, yourimage.e02, yourimage.e03. When this occurs, it is imperitave that original filenames AND extensions be preserved so that they can be re-instantiated upon delivery to an end user (otherwise it will not be possible to put the sequence back together in the proper order). | |||
CAD Formats
Deposit the native CAD file together with a derivative PDF and make both deliverable. The PDF provides an alternative “fixed” preservation copy, providing mitigation for future obsolescence/rendering risks; while the native CAD file provides a truer version of the original, for users who are able to still read the format.
| Content | Preference | Format | Format Use | Notes | |
|---|---|---|---|---|---|
| Preservation | Delivery | ||||
| 2D CAD Drawing | Preferred | Portable Document Format (PDF) | X | X | embed fonts and linked files; rendered by File Delivery Service (FDS) |
| AutoCAD Drawing (DWG) | X | X | embed fonts and linked files; rendered by File Delivery Service (FDS) | ||
| Drawing Interchange Format (AutoCAD DXF) | X | X | embed fonts and linked files; rendered by File Delivery Service (FDS) | ||
| 3D CAD Drawing | Preferred | Portable Document Format (PDF) | X | X | embed fonts and linked files and embedded 3D content in U3D or PRC format; rendered by File Delivery Service (FDS) |
| AutoCAD Drawing (DWG) | X | X | embed fonts and linked files; rendered by File Delivery Service (FDS) | ||
| Drawing Interchange Format (AutoCAD DXF) | X | X | embed fonts and linked files; rendered by File Delivery Service (FDS) | ||
| Extensible 3D Graphics (X3D) | X | X | prefer xml encoding to binary or vrml; rendered by File Delivery Service (FDS) | ||
Audio Formats
| Content | Preference | Format | Format Use | Notes | |
|---|---|---|---|---|---|
| Preservation | Delivery | ||||
| Audio | Preferred | Waveform Audio (WAV) | X | ||
| MPEG-4 Audio (MP4) | X | ||||
| MPEG 1/2 Audio Layer 3 (MP3) | X | Delivered by Streaming Delivery Service (SDS) | |||
| Accepted | Audio Interchange File Format (AIFF) | X | |||
| RealAudio | X | Delivered by Streaming Delivery Service (SDS) | |||
Word Processing Formats
Deposit the native word processing file together with a derivative PDF (PDF/A if possible) and make both deliverable. The PDF provides an alternative “fixed” preservation copy, providing mitigation for future obsolescence/rendering risks; while the native word processing file provides a truer version of the original, for users who are able to still read the format.
Documents should not have DRM, including passwords or encryption.
...
As stated in the Digital Repository Service (DRS) Policy Guide, the DRS will accept content in any format. Note, however, that preservation results may vary depending on a format’s technical nature, the current state of preservation understanding, and the availability of appropriate strategies, tools, and workflows.
The following resources are recommended for general considerations and format selection good practices. The information outlined in these resources is fully consistent with our own approach to format analysis and selection:
- Digital Preservation Coalition’s Digital Preservation Handbook: File Formats and Standards
- Library of Congress’s Sustainability of Digital Formats: Sustainability Factors
- Library of Congress’s Recommended Formats Statement
- National Archives and Records Administration’s Records Management: Tables of File Formats
As useful as these general recommendations are, there are always important local considerations. If you are working with an on-campus digital production unit, for example, Imaging Services or Media Preservation Services, they will be able to offer helpful guidance on format selection in their specific areas of expertise. Additionally, the Digital Preservation Services team is always available for consultation regarding your individual needs. Please contact us at digipres@HU.onmicrosoft.com.