Motion Picture Film Maximum Capture - 4K DPX [MPD-P1]
Record Type: Digital Output from Motion Picture Film Source
Expected Use: Preservation Master
Product Name: Motion Picture Film Maximum Capture - 4K DPX [MPD-P1]
Product Purpose: The purpose of this product is to mitigate risk for loss of information. This file is at an appropriate information capture level to substitute for the original record if the original record copy is no longer viable.
Nature of Source Material: All 35mm film elements (black and white or color) and 16mm camera-original elements with or without optical sound
- in an advanced stage of deterioration as demonstrated by a determination of “High” or above on the At Risk Assessment Guide and
- where a preservation film element cannot be created by photochemical means and
- all possible significant visual picture quality and auditory information is carried forward.
Possible File Derivatives: 4K DPX (Digital Picture Exchange) preservation master files can make 4K ProRes 4444 MOV (Quick Time File Format) and 4K or 2K DPX reproduction master files, and 4K or 2K DCP (Digital Cinema Package) distribution copies. The DPX sequence may be synced with an associated WAV file to make the derivative.
Other Information:
- If the source element contains a composite soundtrack, the soundtrack image will be contained within the DPX file sequence. This requires films with soundtracks to be captured at greater than 4K resolution to ensure the capture of a 4K image area.
- Due to its very large file size, it is not accessed directly by researchers and only sent to vendors under certain circumstances.
- The integrity of the source aspect ratio will be retained.
- This file will not be altered in any capacity except for one-light color timing to be employed at the initial capture stage.
File Properties
| Container Format |
|---|
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The capture process may result in two separate files linked by metadata. Image Data
Audio Data (if present) |
| File Specifications |
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Image Data
Audio Data (if present)
Typical image file sequence size: ~102.7 GB/minute or ~6 TB/hour |
Quality Control
Item Level Evaluation: Manual Quality Analysis
DPX technical metadata may be examined and validated using software like the Federal Agencies Digital Guidelines Initiative (FADGI)-developed embARC tool. Visual quality control (QC) may be performed using DPX editing/playback software and a professional monitor. In order to perform automated aspects of visual QC, the DPX sequence must first be transcoded to an uncompressed or other high-quality video file. Test plans are limited by software capabilities. The National Archives and Records Administration (NARA) is continuing to improve and refine its QC processes.
Equipment/System Evaluation
NARA implements scheduled service and calibration protocols according to manufacturer recommendations as well as on an "as needed" basis.
Metadata
NARA saves DPX sequences in folders named to associate the files with external sources of descriptive and technical metadata. The folder name is a unique identifier composed of the item’s record group, series, item number, and reel number (ex. 255-HQ-199-R2). NARA uses the BagIt file packaging specification to generate manifests of the files in a DPX sequence, as well as checksums for each individual file.
The following technical aspects of the DPX sequence and files are evaluated during metadata QC:
- Image Area Resolution (4096x3112)
- Color Model (RGB)
- Bit Depth (16 bit)
- Endianness (Big endian)
- Transfer Characteristic (Value 1-Printing density)
- Total number of files (match against sequential numbers in file names to make sure no frames were dropped during scanning)
Fixity
The NARA Motion Picture Preservation Lab uses checksum verification for file transfers and files in long-term storage.
Rationale
For digital products created from film-based source material, the specifications are dictated by the source material’s original characteristics including format and condition. Materials in advanced stages of deterioration as measured on the At Risk Assessment Guide are scanned to include all the available visual information within a DPX sequence, including the optical soundtrack if available. When reproduction copies are needed, a second file without the soundtrack image may be generated through reprocessing the over-scanned image to mask the soundtrack. One-light color timing will be employed as appropriate during the initial capture process, but otherwise, the preservation files are unaltered. Reproduction and distribution files may have additional image improvements such as the use of further color correction or audio cleanup. Restoration tools including dust and scratch removal and scene-by-scene color correction may be applied to special projects, but the original preservation scan will not be altered.