Video specifications

From UA Libraries Digital Services Planning and Documentation
Revision as of 10:46, 9 October 2015 by Jlderidder (talk | contribs) (Image and Sound Processing)

The following are the 2015 specifications for video digitization at the University of Alabama Libraries.


  • Technical metadata will be captured in AS-07 MXF format.


Reproduction Setup

Video and Audio setup must be performed for each tape to ensure alignment with source tape and optimal reproduction. If bars are present on a tape the luma gain as well as the chroma gain and phase shall be adjusted so as to meet the standard values of the bars using a calibrated waveform monitor and vectorscope. If tone is present on a tape the audio level shall be adjusted as early on in the signal path as possible so that the tone is at 0VU on a VU meter or -18 dBFS on a digital/peak meter – using calibrated precision meters.

If there are either no bars on a tape or the bars are misrepresentative of the content on the tape (i.e. there are clear chroma and luma errors) the luma and chroma shall be adjusted according to the content on the tape. References for adjustment may include skin tone, sky, known black and/or white objects, etc.

If there is no tone on tape the audio levels shall be adjusted so that content averages 0VU and -18dBFS with peaks not to exceed 0dbFS and with no added analog oversaturation or digital clipping. All level adjustments should be performed as early on in the signal path as possible.

All tracks of audio must be checked for existence of audio content. All audio content on all channels shall be transferred in full.


Signal Path

  • All components in the signal chain must be tested and known to pass the audio and/or video signal without alteration (level or quality) at null.
  • Calibrated high quality distribution amplifiers or routers must be used for any signal splitting and distribution. No other substitutions may be used.
  • The most direct and clean signal path must be used at all times from source to destination. There may be no devices inserted in the signal path that are not being used.
  • If there are multiple destination formats being used in the transfer the signal path must be routed in parallel. No daisy-chaining of devices may occur.
  • The highest quality signal format (composite, S-Video, Component, SDI, etc.) available for the source media type must be used throughout the entirety of the signal path from source through destination. Exceptions to this must be explained and requested prior to performing the transfer.

Image and Sound Processing

1) Preservation and Access Masters

  • No image or sound processing such as dropout compensation, noise reduction, audio equalization, or limiting shall be used in the creation of the Preservation and

Access Masters.

  • All Preservation and Access Masters shall maintain their source formatting, including interlacing, frame rate, aspect ratio and recording standard.

2) Access Copies The Access Copies shall be de-interlaced. Levels may be adjusted

Destination File Format Specifications

  • The preservation master:
    • will be FFMpeg
    • Video encoded using 10-bit YUV 4:2:2 uncompressed codec with the FourCC ‘v210’
    • Audio encoded as uncompressed PCM, 48kHz
    • Maintain the original aspect ratio, recording standard, interlacing, number of audio channels and auxiliary information such as original timecode and closed captioning.
  • The Access Master:
    • QuickTime wrapper (.mov extension)
    • Video encoded using the FourCC ‘dvc ‘.
    • Audio encoded as uncompressed PCM, 48kHz
    • Maintain the original aspect ratio, recording standard, interlacing, number of audio channels and auxiliary information such as original timecode and closed captioning.
  • Access Copy:
    • QuickTime wrapper (.mov extension)
    • Video encoded using the H.264 codec.
    • Audio encoded as uncompressed AAC, 44.1kHz, 256kbps
    • Aspect ratio of 4:3 (640 x 480) using a square pixel aspect ratio.
    • Bitrate of 5000kbps
    • Maintain the original recording standard, frame rate, number of audio channels and auxiliary information such as original timecode and closed captioning.

Timecode

The original timecode of the source tapes shall be regenerated and maintained in the destinations. When timecode breaks are encountered, timecode should continue in “jam sync” mode to enable continuous timecode. The original timecode, with breaks, should be documented in the auxiliary timecode track of the QuickTime wrapper.

If there is no source timecode, original program shall start at 01:00:00:00.

Head and Tail Content

1) Preservation Master

  • All source head formatting, such as bars and tone must be included.
  • In the event that program ends prior to the end of media the tape shall be checked through the end of the tape to ensure awareness of any additional content.
  • In the event that there is additional content, all content on the tape shall be captured. In the event that there is no additional content the file should contain the end of program followed by 10 seconds of additional tape playback.

2) Access Master and Access Copy

  • All non-program material at the head and tail of the tape, such as bars, tone or excessive black/silence should be removed to make for a better viewing and listening experience.

Reference Files

9. REFERENCE FILES

a. GENERATING REFERENCE FILES:

At the beginning of the project, 20 seconds of bars and tones representing each setup used for reformatting tapes shall be digitized using the following specifications:

  • The signal generator shall replace the playback device in the signal path
  • The test signal shall be routed through the same signal path as the audiovisual signal from the playback device
  • The signal generator shall use the same output format as the playback device it is representing
  • The bars shall be SMPTE bars for 15 seconds followed by 5 seconds of black.
  • The tones shall be 2 channels and shall consist of 5 seconds of 50 Hz, 5 seconds of 1000 Hz, and 5 seconds of 20kHz, all at -18dBFS, followed by 5 seconds of no tone. Note that the silence shall consist of the signal generator being muted, and shall represent the noise floor of the signal path post playback device.
  • The file specifications shall match the preservation master destination format. The resulting files shall also be encoded using the same signal path/software and settings, matching the specifications for the access master and access copy files.

For instance, where two setups are used to transfer U-Matic tapes via S-Video, and VHS tapes via composite, (2) 20-second preservation master level files will be generated. If more workstations were to be used additional files must be generated for each one. In addition, access master copies and access copies will be generated, resulting in a total of (6) 20-second files – 2 preservation master level, 2 access master level, and 2 access copy level files.

Each “setup” shall be assigned a 4-character alphanumeric system ID containing no spaces and only lowercase characters. This will be used in filenaming below and incorporated into system metadata.

Folder, File Names and Metadata

The files shall be placed in a directory structure using the following conventions and the Reference Files folder shall be placed at the root level:

CollID/
   collID_sequenceID/
     collID_sequenceID.mov
     collID_sequenceID.ffmpg
     collID_sequenceID.mxf.xml

The filename shall be embedded into each file.

The CollID will be established in the contract. SequenceID will begin with 1 and increment with each item; the sequenceID will be left-padded to a total of 7 characters. For example, if the collID is u0007_0000001, the first item digitized would be u0007_0000001_0000001, and the second would be u0007_0000001_0000002, and so forth.

Metadata

1) External

2) Embedded

  • Full Filename with extension (as Description)
  • Organization Name (as Producer)
  • “Reference File”: Corresponding full reference filename (as Comment)
  • Source Item ID (as Information)
  • Rights Statement (as Copyright)
  • Title information (as Title)