Motion Picture Film Reference Delivery HD MP4 [MPD-D1]
Record Type: Digital Output from Motion Picture Film Source
Expected Use: Distribution Copy
Product Name: Motion Picture Film Reference Delivery HD MP4 [MPD-D1]
Product Purpose: The purpose of this product is to respond to reference requests. It has added National Archives and Records Administration (NARA) identification slates and may have additional overall digital color or density adjustments applied, as well as adjustments for clarity of the audio. The file is suitable for delivery in the research room and online National Archives Catalog access and is not retained by the Motion Picture Preservation Lab.
Nature of Source Material: This product is created from 4K ProRes 4444 MOV (QuickTime File Format), HD (High Definition) AVI (Audio Video Interleaved), or MP4 reproduction master files.
Possible File Derivatives: Derivatives are not made from this product category.
Other Information: Previously the Motion Picture Preservation Lab investigated other file types for reference access and some legacy 2Mbps SD (Standard Definition) MP4 files may be found in the research room and the National Archives Catalog. This 2Mbps HD MP4 specification was developed in 2016 to describe distribution files for reference workflows.
File Properties
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| File Specifications |
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Target Total Bitrate: ~2.2Mbps
Video Data:
Audio Data:
Typical file size: ~15.8MB/minute or ~0.95GB/hour |
Quality Control
Quality Assurance and Quality Control for Distribution Copy Video Files
NARA uses a commercially available, automated batch processing software tool to evaluate specific quality metrics for files created directly from film captures (see MPD-R1 and MPD-R2). The MP4 derivative described here is sourced from a 4K ProRes 4444 MOV, HD AVI, or MP4 reproduction master file following the NARA Film Reference standard operating procedure (SOP). We rely on visual quality control (QC) and spot checks to confirm completeness and accuracy of slates, as well as technical characteristics of the files. If an MP4 does not meet specified requirements, a new file is created from the source.
Metadata
The MP4 filename contains metadata that associates the file with external sources of descriptive and technical metadata. Each filename is a unique identifier composed of the item’s record group, series, item number, and reel number. To distinguish this file from the 50Mbps HD MP4 reproduction/distribution master, a suffix identifying the bit rate is appended to the filename until it is delivered to the Moving Image and Sound Order Processing unit (ex. 255-hq-199-r2_2Mbps.mp4).
Rationale
These files are created at a low bitrate optimized to be easily streamed or downloaded from the National Archives Catalog via an internet connection.