Digitizing Video
An Introductory Course by Kirk Pearson
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Unit
One:
Introduction to Digital Video
Unit
Three:
Computer Readiness
Unit
Five:
Video Capture & Editing
Analog/Digital Camcorders
The primary device consumers use to acquire digital video footage is called a camcorder. For the most part those recording analog (magnetic/nondigital) format are not prevalent in the market place anymore. Camcorders use electronic chips called 'CCDs' which stand for charge coupled devices which sense images (as light or bright and dark regions) coming through the camera lens and convert it to data that can be stored digitally (i.e., represented by 0s and 1s, the base language of the computer). Let's discuss CCDs for a moment since, as the primary component in a camcorder, CCDs affect the quality of the initial image/data, and as we all know, garbage in-garbage out. (For the insatiable appetite, a more detailed presentation and interesting illustration can be found here.)
Most consumer-level camcorders have one CCD, while prosumer-/professional-level camcorders have three and are more expensive. The more CCDs the better. With only one, an array of color filters is placed over the CCD to differentiate the color input. With three CCDs, each one receives the incoming light as its assigned primary color (achieved by splitting it with a prism) and then electronically combines the separate signals again to create the digital data.
There are a number of other attributes associated with the CCDs themselves, such as their size, resolution (number of pixels/picture elements or individual dots captured by them), and scan capabilities. Although larger CCDs are typically found in the more expensive camcorders, there is disagreement on whether bigger means better. Similarly, a resolution of 720x480 pixels (about 345,000 pixels) is generally considered sufficient for quality DV format, but a common trend is to increase the CCD resolution to allow the camcorder to also function as a digital camera and take high-quality still pictures (e.g., 2-megapixel or 2,000,000 pixels). Note that camcorders also come with a maximum picture resolution and that by comparing it to the CCD resolution, you can determine the amount that the camcorder is digitally zooming the image (none is best) from what it can capture, to what it is actually saving. And finally, scan capabilities refers to how the camcorder stores the incoming image frames. It can either be interlaced (each frame is put together by two separate shots) or progressive (each frame is one shot divided into two fields). This has to do with NTSC (National Television Standards Committee) standards that require each video frame to be divided into two fields. Progressive scan is the better choice (due to motion discrepancies between the separate shots of interlaced scanning), especially if high-quality still images are something being done with the camcorder.
There are quite a few other metrics that can be used to evaluate camcorders.
The codecs used to compress the incoming image were briefly touched upon
in unit one (their attributes will be discussed more later). Lens capabilities,
programming, and external features such as controls, LCD panel, and input/output
ports are a few of the others. We'll touch on some of these as we go along
but there are many web resources and reviews such as camcorderinfo.com
and mini-DV
units that compare units and features (in case you're shopping).
Computer Components and Considerations
The computer is used in a number of different ways to accomplish a variety of digitizing video tasks. It can be used to capture analog or digital video, edit, render, and output it (online or disc) depending on the hardware and software components available. We'll take a look at a few of the hardware components in the paragraphs that follow (and software in unit four). For purposes of our discussion we'll focus on PCs. (If you have an Apple Computer product and need more specific information or application than offered in this course, I suggest you conduct a search for relevant resources such as Digital Video on a Mac. There is a lot of video work done on Apple products and I know there are also a lot of resources available on them too.)
Beginning with capturing, or the process of getting your video data into the computer, what you begin with has a bearing on the hardware that you'll need. Most DV camcorders have an IEEE1394 (called 'Firewire') port, as do most contemporary computers although they don't look exactly the same, and if this is your configuration, you are good-to-go with respect to capturing hardware. If your computer doesn't have a Firewire port, adapter cards can be bought and installed in your computer's expansion slots which will provide them. There are also simple DV-capture cards which essentially are a IEEE1394/Firewire card bundled with some software that allows video capture/editing (and sometimes DVD burning) from a DV camcorder.
Older camcorders and computers have a variety of other input/output ports which necessitates some planning to arrive at a workable solution. This will be discussed further in the unit on Computer Readiness.
(Firewire - DV camcorder ports/cables)
It should be noted that some video and sound cards come with the capability of inputting data. Again, ports vary depending upon makes and models but if you have one of these, you'll probably need adapters to make the actual connections between your device and the computer. Adapter plugs and cables are available from electronics stores and in some cases, from the manufacturer of the camcorder/input device as well.
Once the video is captured you will want to process (edit and render) it. This involves taxing operations on the computer's hardware and to a large degree, the hardware required is determined by the software used. When shopping for software you will want to carefully examine what is recommended by the manufacturer and determine how closely your computer matches the recommendations. Generally speaking, you will want at least the following hardware for most consumer-level software packages, but do check the software manufacturer's recommendations (these are more stringent than the minimum requirements which should be exceeded if at all possible):
CPU: 1 Ghz or higher, MEMORY: 256-512MB RAM, OS: Windows 2000-XP, GRAPHICS/SOUND:
Direct X compatible
HARD DISK: 300-800MB free for software, and about 1GB for every 5 minutes
of video that you intend to capture
CD-ROM, DVD burner drive for creating DVDs
PORTS: varies depending upon desired input method but will probably involve
Firewire or USB 2.0
On the output end of things, a DVD burner is pretty much a necessity since they hold much more data than a CD-ROM. They come in a variety of flavors, both in terms of what type of discs they can read/write as well as how fast they do either. What is DVD gives definitions for most flavors of discs on the market currently. It is vitally important to know what format your intended target uses (e.g., settop or living room DVD player). These normally read in the flavor or format DVD-R, which is the one most commonly used in the video business. Most players read other formats as well but some read the competing standard DVD+R instead. Quite simply, if you don't match your computer DVD burner drive disc format with your intended player (or vice versa), you will be trying to plug a square peg into a round hole. A really great resource on DVD technology is 'dvd-demystified.' It lists a number of questions (with answers lower on the page) and appears quite long but is set up this way to allow browser 'find on this page' searches.
Digital Video on a PC is one of many sites that offer more information about what hardware considerations might be relevant to you. Once you know what you need, you can then assess what you have and obtain necessary components and connectors to 'make ends meet.'
A/D Converters
You should be aware that in some cases using a camcorder as the input device isn't possible, e.g., unreconcilable ports on an older unit. There are at least a couple of options to consider if this is your situation. If you have analog media already, for example VHS video tapes, you can use a VCR as your input device. This would necessitate making a connection from the VCR's ports/jacks which are usually known as RCA connectors. They are round and are color-coded (yellow for composite video, white for mono-only audio or left channel, and red for right channel audio). Newer VCRs may also have what is called an S-video port which is a round connector with 4 small holes and is considered a higher quality format than that provided by RCA composite video.
(RCA & S-video ports/cables)
If you use a VCR as your input device, you'll need something attached to the computer that will accommodate the RCA and/or S-video connectors coming from it. When I built my computer I incorporated a mid-level video card which provided for an S-video input (in my case my VCR doesn't have an S-video so I must use special adapter cables that basically have RCA connectors on one end and an S-video on the other end). And since I knew I would be digitizing video and needed audio input, I selected a motherboard to build it on which provided an audio input negating the need for a special sound card that would do this. If you have a similar setup you may want to consider a similar configuration.
Another alternative is something called an analog/digital (A/D) converter or capture device. It is usually an external capture tool which essentially is a small box with an assortment of input and output ports. They commonly have RCA and S-video ports available for video and audio input, and Firewire or USB 2.0 ports for output (to the computer). Generally, devices with a USB output port capture using either MPEG-1 or MPEG-2 format while those with a Firewire output port capture in DV video format which retains a higher quality and is the better format to begin the editing process with. (An article that discusses converters and another alternative, dedicated DVD recorders such as the HP DVD Moviewriter, can be found here.)
(Pinnacle MovieBox DV - example of a capture device with a Firewire output port)
Accessories
Perhaps by now you are starting to formulate some ideas of your own for how you can digitize video in the easiest and least expensive way. I won't thwart those ideas much more but wanted to make you aware that there are all kinds of accessories that can make the process more enjoyable, or at least easier and possibly higher quality.
On the camcorder end there are things such as microphones, tripods, extra batteries, lights, etc. If you are just starting out and are shopping I'd suggest putting a little thought into what kind of video you will be taking. Keeping this in mind as you shop, some accessories might enable you to increase the quality of the footage that you acquire and this is important since you only have one shot at this. Articles such as 'DV Camcorders' or 'How to Choose' are helpful in determining which features or accessories might be useful.
Depending upon your computer and camcorder (if you're using one as the input device), there are a number of variations to the hardware you could consider (if you can think of features as an accessory). Different features can have different attributes which will affect the speed and/or quality of the overall job (e.g., composite versus S-video ports). For any hardware component that you are considering, do some shopping and get familiar with the features of units a step up and a step down from the one you are looking at to better determine costs/benefits.
A relatively recent 'accessory' on the market with respect to digitizing video hardware is the DVD burner/VHS video combo unit. Like it sounds, it is capable of burning DVDs directly from a VHS tape. Some units allow the creation of very simple menus and some do not. They are designed for people who don't want to do any editing and are happy with a DVD laid out just as the source tape that they are using is. It should also be noted that you are unable to color/brightness correct or boost the audio signal being 'input' from the tape as you can with some of the editing software packages. If you have tapes that are of marginal quality this may be a significant reason for going the traditional road of using the computer to process your project. From the research that I have done so far, variations in the type of discs that can be recorded and/or played in such units is significant and compatibility issues between different manufacturers of these units as well as computer DVD drives are still being worked out. It remains to be seen whether or not discs from such units, even if compatible with your computer's DVD drive, would output files that would be compatible with the various video editing software packages. There are a number of variables that would need accounted for to avoid frustration and disappointments down the line. We'll discuss some of these later in the course.
(Image sources: BestAnimations.com, Altavista.com, images.google.com, and Pinnaclesys.com)
