Preservation

Video Maximum Manual Capture - SD [VID-P1]

Record Type: Digital Moving Images from Video Source Material

Expected Use: Preservation Master

Product Name: Video Maximum Manual Capture - SD [VID-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 standard definition video with or without sound where there is a need to ensure that all significant visual and auditory information is carried forward. This includes both analog video and digital video source material that cannot be extracted as data and must be ingested via an analog video or SDI (Serial Digital Interface) connection. These formats are identified in section B2.4of International Association of Sound and Audiovisual Archives (IASA) TC-06 in Classes 1 and 2.

Possible File Derivatives: This product is used to make standard definition (SD) MPEG-2 50MB 4:2:2 reproduction masters and distribution files.

Other Information: Due to its very large file size, this product is generally not accessed directly by researchers. 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.

File Properties

Container Format
Container: AVI (Audio Video Interleaved)
File Specifications

Target Total Bitrate: ~228 Mbps

Timecode: Source LTC/VITC

Video data

  • Frame size: 720x486
  • Video codec type: Uncompressed
  • Video codec: v210
  • Video bit depth: 10 bit
  • Video frame rate: 29.97 fps
  • Chroma subsampling: 4:2:2
  • Interlaced

Audio data

  • Audio channels: 4 discrete (2 AES pairs)
  • Audio codec: PCM
  • Audio sample rate: 48 kHz
  • Bit depth: 24 bit

Typical file size: ~1710MB/minute or 102.6 GB/hour

Quality Control

Quality Assurance and Quality Control for SD Video Products

The National Archives and Records Administration (NARA) uses a commercially available, automated batch processing software tool to evaluate specific quality metrics. Below is an outline of our current processes for SD AVI formatted products.

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 (or are not accurate) on the source material, video levels are adjusted to the original content; setup, video level, chroma, and hue are the primary adjustments made. The automated SAMMA (System for the Automated Migration of Media Assets) workflow does not include color bar adjustment for individual tapes.

Metadata

The 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, and item number.

Embedded metadata compliance: NARA is working to develop embedded metadata guidelines for reformatted video. Additional information will be added to this site when available.

Technical metadata: NARA uses its reVTMD schema for video technical metadata.

Item Level Evaluation: Automated File Characteristics Analysis

Fixity: NARA creates a checksum on the local workstation where the file is created. This checksum is verified once the file reaches long-term tape storage to ensure that no changes have occurred during quality assurance (QA)/quality control (QC) procedures and file transfers on networked storage.

Item Level Evaluation: Automated Quality Analysis

Using automated batch processing software tools, test plans are developed for each format and/or each appropriate project. The test plan allows for some characteristics to be evaluated on an actionable basis (warning, fail, or pass depending on the defined parameters). Others are logged for internal use but are not actionable as a warning, pass, or fail. Aim points for these benchmarks are evaluated against NARA's product specifications as well as NARA-defined aim points which may change depending on specific project goals. The following represents the quality test plan technical characteristics for AVI products.

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

Container technical characteristics checked or logged include:

Check (Warning/Pass/Fail)
  • Video Tracks (number of)
  • Audio Tracks (number of)
  • Mismatch in Audio and Video Duration
  • OpenDML AVI File Format Extension
Logged data
  • File Size
  • Content Layout
  • PIDs allowed for Audio and Video

Video technical characteristics checked or logged include:

Check (Warning/Pass/Fail)
  • Chroma Format Frame Rate (Fps)
  • Resolution (Width/Height)
  • Bits Per Pixel (Luma and Chroma)
  • Resolution Change
  • Video Format
  • Video Signal Levels (Luma/Chroma)
Logged data
  • Average Bitrate (Mbps)
  • Active Pixels (Percentage)
  • Duration
  • Color Bars
  • Black Bars
  • Brightness
  • Contrast
  • White Point
  • Freeze Frames
  • Cadence Break
  • Upconversion
  • Field Order

Audio technical characteristics checked or logged include: 

Check (Warning/Pass/Fail)
  • Sampling Frequency (Hz)
  • Audio Channels (Number)
  • Bits per sample (Number)
  • Duration
  • Maximum Level
  • Audio Clipping
Logged data
  • Bit Rate (Kbps)
  • LFE Channels (Number)
  • Test Tone
  • Average Level
  • Phase Mismatch
  • Level Mismatch
  • Loudness
  • DialNorm-Loudness Mismatch
  • Misplaced Channels
  • Background Noise
  • Transient Noise
  • Wow and Flutter
  • Jitter Noise
  • High Frequency Noise
  • Overmodulation

Rationale

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 wrapper and codec was one that NARA staff looked at very critically. We continue to monitor developments in the area of wrapper, codec and toolset development.  We see AVI, MOV, MXF, and MKV as the most viable options.  Each has pros and cons. 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.

The digital preservation master products produced by the Audio-Video Preservation Lab are in line with published guidelines and best practices including the IASA TC-06: Guidelines for the Preservation of Video Recordings.

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

Top