The Preservation of Analog Video through Digitization
by Scott Pennington and Dean Rehberger
For many of us, having videotape on the shelf seems like a good way for us to preserve our oral histories. Tapes are tangible. Unlike the seeming gossamer quality of digital files, VHS tapes seem to have solidity — we can hold them in our hands, line them up on shelves, and pop them into a machine to play. It is a good idea to hold onto your original tapes but, as we know, magnetic tape can offer up a host of preservation problems (see Preserving Tape) so migration to digital format is a must.
While it is easier said than done, migrating an analog videotape collection from tape-to-digital format is not as difficult as you might think. Given the proper equipment and time, it can be a manageable project for individuals and small institutions. Holders of very large media collections may want to consult with experts and may involve robotic systems (see NARA’s process) .
The digitization workflow can be broken down into four steps.
- assessing the collection;
- preparing the analog playback;
- implementing the digitization process;
- and, doing quality control.
The point of this article is to encourage you to migrate your tapes. Often tapes languish because we believe the process is too expensive, too difficult, and we cannot do a “good enough” job. Yet we can’t let “perfect be the enemy of the good,” “good enough” may be the best way to preserve valuable cultural assets before it is too late.
Yet as we review each step, there is noting wrong with coming to the conclusion that a professional is needed. In fact, outsourcing may be the only way to save badly damaged and outdated formats.
Step 1: Assessing the Collection
Many collections will consist of more than one videotape format. Understanding the formats you have in your collection is an important first step to preparing workflow and equipment for your digital migration. If it does not already exist, a simple inventory of the collection should be performed. For the scope of this article, only format type and condition is necessary. While handling the tape, your project may perform other inventory/cataloging tasks.
While performing the inventory, it is a good time to assess the condition of tapes, especially to determine is any needed repairs or other professional handling for preservation. Tape assessment can be a tricky business, but you will be surprised at what you can determine with a little knowledge. A good simple 7 step guide can be found in a Spec Brothers white paper.
Two very good reports on magnetic tape assessment and preservation can be found on at the Image Permanence Institute, “The Preservation of Magnetic Tape Collections: A Perspective” and at Presto Space. Two other very good resources, but need to be purchased, are the standards documents, ISO standard 18933:2012 and AES49-2005 (r2010).
At minimum, a good collection assessment for the purpose of digital migration should document the following information:
- Identifier—This is usually in the form of a tape label. Your collection may already have a standardized tape-naming system. Best practice is to retain that system as part of the digitization process. If these names are not standardized, create standardized file names as part of the digital workflow.
- Condition—Until playback, assessing the condition of the video on the tape is difficult. By using one of the guides referenced above, visible inspection can be standardized and tapes rated on a scale of Very Good (VG), Good (G), Poor (P) and Very Poor/Unplayable (U)
- Tape format—Most collections will consist of consumer format tape (e.g., VHS, VHS-C, Betamax, miniDV, Digital8, Hi8). If created by a professional crew, you may have professional format tape (e.g., ¾” in. U-matic, 1 in. type C, Betacam). If unsure, the Texas Commission on the Arts published a guide to videotape identification and assessment in 2004 (http://www.arts.state.tx.us/video/pdf/video.pdf ) This is an excellent guide (supplies photographs of different tape formats, including measurements) to help identify subtle differences in formats.
- Date—determining a tape’s date can be more tricky than one thinks. Hopefully it is on the tape label or part of the tape’s contents. Other materials that were part of the project (field notes) may help. Tape format can only be used for a general time frame since many formats were used long after they became obsolete and used for long periods of time.
Once you have completed the inventory, you have two basic questions to answer before moving on to the next step. Actually lots of questions may come up, but answering “no” to one or both of the following questions may mean that you need to outsource the project.
Given the collection inventory, does your project have all of the decks necessary to play the tapes?
For example, if your collection consists of Betamax, VHS, and VHS-C tape, your digitization workflow will need to include a deck for each format, or an adaptor for the VHS-C tape to fit a normal VHS cartridge. Each format will require a separate deck or adaptor, and each deck should be professionally inspected for proper operation before tapes are inserted.
Given the collection inventory, are the tapes in good enough condition to play without professional reconditioning?
Using your guide to tape condition, if a tape is deemed poor or unplayable, these should not be put into a tape deck (VTR). Tapes in this category can damage good equipment and slow or stop your digitization process. Be wary of tapes in an unknown or damaged format and seek professional restoration help when necessary.
Step 2: Preparing the Analog Playback
VTRs (Video Tape Recorders) for each format
Digitizing videotape requires the ability to play the tape format your project needs to migrate forward. If your project lacks all of the decks necessary for playback, there may be other sources for the equipment. EBay is a popular source for older decks and reputable dealers are not difficult to find (do check user satisfaction and reviews of dealers). But you can be more crafty, and you will often be surprised where you can find old equipment. Many community colleges teach video editing and have old VTRs stacked in closets or back rooms. They often keep them around for occasional use in migrating their own tape forward, but several projects have had great success working with local colleges on projects.
For common consumer formats, such as VHS, Betamax, miniDV, or Hi8, local public schools, churches, Salvation Army Stores and similar places often have decks they may be willing to rent/loan/sell/give to oral history projects. You would be surprised at how many institutions stack and keep old video equipment (including your local TV stations) and are often happy to see it go good homes.
When beginning a new analog-to-digital migration, inspect any previously unused VTRs for proper functioning and operation. One of the key elements of VTRs are the Heads (the transducers that scan the video tape during playback and recording). For a good online guide to understanding the video head and how to clean them, see “Notes on the Troubleshooting and Repair of Video Cassette Recorders.” While the general rule of thumb is to clean heads every 50 hours of use (25 if used in smoky or dusty environments), some experts will say to avoid excess cleaning. Video heads are delicate and easy to damage so proceed with caution.
Best practice in using any VTR is to use only a professional-level, playback-only decks (as opposed to recorders). In practice, many projects use VTRs that are available. If your project uses a consumer VTR, a good suggestion is to always remove the safety tabs on tapes (which renders tapes unrecordable) before inserting them into the recorder, as well as taping a “NO” sign over the recording button on the playback deck.
Finding working VTRs for some older formats is becoming more and more difficult. If you have a box or two of 2-inch quadruplex videotape from the 50s and 60s, finding a working player (they are bigger that a Smart car) is very tricky and it is time to call on the professionals.
Step 3: Implementing the Digitization Process
While thinking about important pieces of equipment for the digitizing process, don’t forget the monitor. Best practice is to use a broadcast quality, editing monitor to view constantly the video output from your VTR as the signal is being captured. In practice, many projects can only afford a television as a monitor. In most cases, when you want to simply monitor your video signal as it will look, most standard televisions now produce a quality signal and will be effective. However, if your project includes video signal critical tasks such as color correction, you should use a high-resolution broadcast monitor that can be properly calibrated to display your signal consistently and accurately.
For a good snapshot of the broadcast monitor vs. video monitor see Final Cut documentation. In the end, the key is to monitor the signal coming from the VTR. Watch for obvious signs of tape lag, picture roll, or other issues caused by tape deficiencies and stop the capture process to correct as necessary. Digitization is not a “start the process and go do something else” project.
At this point, you have determined that you have good tapes that you can play and watch. So what you have is a good analog video. To work with it on a computer it needs to be digital. To make this conversion we need the aptly named piece of equipment called an analog-to-digital converter (ADC).
Capturing the video signal from a modern digital camera for editing is often so easy that this step in the analog-to-digital migration path can be overlooked. However, the method used to capture a digital stream from analog is the most critical portion. Once a tape becomes digital, future migration of that file depends heavily on the original quality of that file captured.
You can cheat by plugging a VHS tape deck into the analog ports on a camera and capturing the playback signal through firewire or USB to a computer. It will appear on the computer screen to give a good digital copy of the tape. But this is not the case. Don’t cheat.
To understand the reasons, a working knowledge of analog-to-digital conversion helps. For an explanation of how audio analog-to-digital conversion works, explanation of bit depth and amplitude, and more see the Video Preservation Web site as well as Kara Van Malssen’s “Digital Video Preservation and Oral History.”
At the very least, a bottom-end ADC in the $100-$200 price range can produce acceptable results. Composite video can be attached to one side of the ADC (the familiar red-white-yellow cables) and a digital signal comes out the other side of the ADC. If your deck offers S-Video out, use that port to transmit the video signal, and use the red and white to carry sound to your computer. Understand that this lower-end signal compromises some of the original video vibrancy from the recorded tape. Even so, this digital signal is richer, and a more accurate representation, than from a non-dedicated converter such as in a video camera.
Best practice is to use a higher-end broadcast quality ADC (price ranges begin around $1000) and at least component video signals[i]. Higher-end ADCs capture better quality video from the VTR and produce better digital representations of that video. Your signal will be significantly less muddy, with richer colors and more detail in the video signal. Even as this article is being written prices are coming down and there are a significant number of ADCs in the $400.00-$800.00 that can produce very high quality signals. It pays to do a bit of research and review stalking.
Finally, you will need to have video capture software. Applications such as Final Cut Pro, Adobe Premiere Pro, Avid Media Composer, Sony Vegas Pro, iMovie, Pinnacle, or are non-linear editors for video, also known as NLE applications. Each of these applications works differently, handles files differently, and requires different specific information for capturing and saving uncompressed digital video.
Final Cut, Adobe, Avid and Sony are professional grade editors. Trying to determine the best is like determining the best car when looking at the top four luxury vehicles and as with buying a car price may be the determination (Avid, $2500.00; Final Cut, $300.00; Sony, $680.00; Adobe, $800.00). There are many consumer grade software packages like iMovie and Pinnacle that can work very well for capturing small and personal collections.
Review the user guide for your chosen application, and make sure personnel on the project understand the application, file handling within the application, and how to save files using a standardized file-naming scheme.
Step 4: Doing Quality Control (QC)
One of the more overlooked steps in converting analog-to-digital video is the quality control portion of the process. Best practice calls for viewing the video as the capture takes place, and this is usually possible even if only one person runs the capture equipment and digitizes several videos at once.
Many of us could cite examples that bring terror to the heart when QC is not a regular part of any workflow. Lack of monitoring the process can mean hours of tape converted with dropped frames or no sound, incorrectly labeled files transferred from incorrectly labeled tapes (we knew one oral historian who digitized 22 interviews and did not realize until she viewed the results that she had incorrect settings and had failed to capture the sound). QC is good medicine for all projects and at every step of the project.
The captured video should also always be viewed. Best practice is for trained video professionals to monitor and check the file-creation process. To save funds and expert time on projects we have asked non-specialists who may be part of the project, volunteers, or in some cases clerical staff to watch the video for problems. Personnel can be given access to down-sampled versions of the files, and by watching may spot problems in the digitization workflow. Specialists involved in the analog-to-digital conversion process should always view the first few files completely.
Citation for Article
Pennington, S., and Rehberger D. (2012). The preservation of analog video through digitization. In D. Boyd, S. Cohen, B. Rakerd, & D. Rehberger (Eds.), Oral history in the digital age. Institute of Library and Museum Services. Retrieved from http://ohda.matrix.msu.edu/2012/06/preservation-of-analog-video-through-digitization/.
Pennington, Scott and Rehberger, Dean, “The Preservation of Analog Video through Digitization,” in Oral History in the Digital Age, edited by Doug Boyd, Steve Cohen, Brad Rakerd, and Dean Rehberger. Washington, D.C.: Institute of Museum and Library Services, 2012, http://ohda.matrix.msu.edu/2012/06/preservation-of-analog-video-through-digitization/
This is a production of the Oral History in the Digital Age Project (http://ohda.matrix.msu.edu) sponsored by the Institute of Museum and Library Services (IMLS). Please consult http://ohda.matrix.msu.edu/about/rights/ for information on rights, licensing, and citation.