User:Videoatrisk
- DUPLICATION FORMAT
-DVD, Blu-Ray, or Files?: What format will the preservation masters be held on? To what degree will this depend on the estimation of our IP team--entirely, or partially? File formats, compression, codecs, wrappers?
- TECHNOLOGICAL CHALLENGES: Video
-Issues of underscan & overscan areas: Will these be ultimately displayed in delivery/service versions of content? To what extent do we attempt to unify/mitigate artefacting errors in the underscan areas? Will we matte the access DVD copies, if they are to be shown on a computer monitor/flatscreen?
-Closed Captioning: Will digitization simply visually capture CC (as the top line in the overscan), or will a decoder be employed to save & translate CC as metadata to be stored with a preservation master file? Equally challenging may be determining which tapes are CC (in the absence of labeling, original packaging, etc.).
-"Formatted to fit your screen" & Iterative Nuances: How will we address content that has been adulterated for VHS release? Specifically, Walter has noted that several westerns originally shot in Cinemascope exist as such (ie. in letterbox) only during opening scenes and closing credits--the bookended remainder of the film has been squished together, with characters standing very tall and lanky-like to take up all of the 4:3 real estate. Broadly speaking, how do we plan for digitizing content that has been less-than-ideally formatted in its VHS iteration? Granted, VHS itself is a less-than-ideal formatting of moving image content that exists on film, but when do we determine: "this is too much of an aberration from extant film versions to digitize"? Do we ever? On the other hand, do we have a responsibility to digitize/preserve these versions of a work, as they have been seen, learned, and exclusively know by decades of persons? Do we preserve colorizations?
-NTSC, PAL, and SECAM: Failing labeling, playback should indicate which signal standard a given tape is.
-VHS Sub-formats: It is possible some content (non-commercial, and artist-produced tapes) will be on the S-VHS format (or others, though this may prove to be extremely rare).
- TECHNOLOGICAL CHALLENGES: Audio
-Hi-Fi vs. Low-Fi: It will be important to ensure that the recorded audio format persist, and that the vendor's VCRs offer both functionalities.
- VHS FUNCTIONALITY THAT MAY POTENTIALLY BE LOST THROUGH MIGRATION
-Index marks, for those tapes that had marks encoded -Closed Captioning
- POSSIBLE WORKFLOWS
| VHS OUTS | TBC | DIGITIZATION INS |
|---|---|---|
| Composite | Dedicated TBC | Composite |
| Component | Multiformat TBC | Component |
| S-Video | Digital Deck (e.g. Digibeta) | SDI w/ Embedded Audio |
| A/D Card (e.g. AJA) | SDI w/o Embedded Audio | |
| None |
- TBC Features
Bandpass filter: A bandpass filter that removes frequencies of a certain range from a signal in the hopes to remove noise. A lo-pass filter removes all frequencies below a certain point such as 2.5 Mhz. You want a TBC that has an adjustable bandpass because different media work on the different frequencies. For example, VHS operates at approximately baseband bandwidth (the highest frequency) of 3 Mhz while SVHS baseband bandwidth is 5Mhz. So lo-pass of 3 Mhz works great at removing noise from a VHS tape but would cut a lot of useable information from a SVHS tape.
Genlocking: Genlocking align the frames, fields, and lines to an external signal. This is necessary if you plan on switching machine during a transfer because it keeps the signal stable during the switching. It is not really necessary if the media is only coming from one source.
Drop-out Correction: Many TBC have a drop-out correction system which allow the TBC to fill in the missing line of information in drop-out with information from a different line. It most cases, the effectively restores the image to its intended look but does run the risk of adding unwanted information. Use sparingly.
Legalizer: A feature that adjusts the luma and chroma to legal broadcast levels. Generally this feature is frown upon in preservation. It is preferable if this is by-passed.
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