The purpose of this product is to respond to reference and reproduction requests.

This product is created from HD AVI or other reproduction master files.

Container:

• MPEG-2
• Program Stream
• 4:2:2 Profile, Main Level
• Closed GOP, I-frame only

Target Total Bitrate: 50.8 Mbps

Timecode: Source LTC/VITC

Video data

• Frame size: 720x480
• Video codec: MPEG-2 MainConcept
• Video bitrate: 51.1Mbps
• Video mode: CBR
• Video frame rate: 29.97 fps or 24 fps depending on source material
• Chroma format: 4:2:2
• Interlaced scan or progressive scan depending on source material
• Single-pass encoding

Audio data

• Audio channels: 2 (stereo L R)
• Audio bitrate: 224 Kbps
• Audio mode: CBR
• Audio codec: MPEG Layer 2
• Audio sample rate: 48 KHz
• Audio sample size: 16 bit

Typical file size: ~54 MB/minute or 3.1 GB/hour

This product is used to make distribution files.

The Digitization Services Branch’s Quality Assurance and Quality Control (QA/QA) program is evolving as new tools and resources are acquired and implemented. We are moving towards more automated and integrated systems to assure the products we make meet the specifications outlined. Digital products created by the Digitization Services Branch are validated against standardized format specifications and signature files when possible. We use a variety of format specific batch evaluation and validation tools both open source and vendor supplied, to assure technical quality level specifications are met. All files, but especially distribution system specific files, are inspected for successful playback in a variety of tools and environments. Additional quality control workflows are in development.

Equipment/System Evaluation
NARA implements scheduled service and calibration protocols according to manufacturer recommendations as well as on an "as needed" basis.

Metadata
Embedded metadata: NARA is working on embedded metadata guidelines for all file types.
Technical metadata: NARA is finalizing technical metadata schemas for all file types.

NARA is developing an in house job tracking order system to better coordinate work at the Branch level.

Item Level Evaluation: Automated File Characteristics Analysis
Fixity: NARA is evaluating workflows to create and validate checksums for each digital file.