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

All standard definition video with or without sound not at risk due to deterioration or obsolescence.

Current SAMMA Robotic system is restricted to ¾” U-matic tapes only.

Container:

• MPEG-2
• Program Stream

Target Total Bitrate: 50.8 Mbps

Timecode: Source LTC/VITC

Video data

• Frame size: 720x480
• Video codec: MPEG-2 MainConcept
• Video bitrate: 50Mbps
• Video mode: CBR
• Video frame rate: 29.97 fps
• Chroma format: 4:2:2
• 4:2:2 Profile, Main Level
• Closed GOP, I-frame only
• Lower field first
• Interlaced scan
• 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: ~ 360 MB/minute or 21.6 GB/hour

This master file can be used to create distribution files of equal or lesser capture quality.

This product could also be used as a broadcast or production quality deliverable.

Audio and video levels may be adjusted 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 minimal color correction if necessary.

NARA uses a commercially available, automated batch processing software tool to evaluate specific quality metrics. Below is a outline of our current processes for HD MPEG-2 formatted products. The exact aim point values are still in the testing phase. Once these values are confirmed, they will be added to this site. We continue to adjust our benchmarks and workflows as needed.

Color Bar Alignment
Color bar alignment is part of the manual video digitization workflow. Video levels are adjusted to original color bars on the source material when possible. When original color bars are not present on the source material, video levels are adjusted to the original content; setup and video level are the primary adjustments. Metadata is embedded into the video file indicating whether the source tape was adjusted to original color bars or the original content. The automated SAMMA workflow does not include color bar adjustment for individual tapes.

Metadata
Embedded metadata compliance: NARA is working with FADGI to develop embedded metadata guidelines for reformatted video. They will be added to this site when complete.
Technical metadata: NARA uses its reVTMD schema for video technical metadata.

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.

Terms used in the QC protocols are defined in the Glossary of Terms

For digital products created from video source material, the specifications are dictated to some extent by hardware and software capabilities.

Currently, the Video Preservation Lab creates uncompressed video streams in an AVI (Audio Video Interleaved) wrapper for the SD preservation master product option. All video is ingested on equipment that is calibrated to allow for ITU-R Recommendation BT.601 compliance, but also to allow for safe capture of graphics and other computer-generated materials that may contain luminance values in the superwhite range. This method of calibration and capturing supports the most authentic replication of the original source material.

• The choice of a wrapper was one that NARA staff looked at very critically. According to an in-house international survey conducted in the spring of 2010 of over 50 institutions involved with film and video reformatting, the three main choices for preservation products were AVI, QuickTime (.MOV) or MXF (Material Exchange Format). Each has pros and cons. Based on the feedback we received, NARA has decided to use the AVI wrapper for a variety of reasons including:
• Both the robotic capture system as well as the manual capture system can natively capture in AVI. (Only the robotic capture system has the option to capture in MOV; the manual capture system cannot natively capture in MOV.)
• While the AVI wrapper has somewhat limited support for timecode, we are able to capture a start timecode from which the remainder of a timecode track could be generated if required.
• AVI files are playable in a wide variety of open source tools including VLC.

We will continue to monitor codec and wrapper use within the professional community as well as toolsets development and reevaluate our products as needed, especially when HD video reformatting comes to the fore.

NARA’s options for reproduction masters are in line with peer institutions.