Creating Internet Videos on NT Systems

Video and the Internet are a winning combination. Video is unsurpassed as a vehicle of display or demonstration, and it can make the displayed object or process feel alive, vibrant, and present. Anyone who can go online can watch a video on the Internet without traveling or waiting in line. With an Internet video, you can teach your employees or clients how to use your product, for instance, and they can watch a video at their leisure, without leaving their computer stations. Video on the Internet is an exciting development.

Why Internet Video?
The Internet is the perfect medium for up-to-the-minute information. You can present the same information on CD-ROM or videotape, but you face the necessity of promoting, distributing, and delivering the product. Information presented on Internet video, however, is universally available as soon as you create the video. Internet distribution lets you protect sensitive information: You can password-protect your site and code your video so that viewers can't save it to a disk. Anyone can watch your Internet video anywhere, anytime, and with any computer system.

This situation sounds ideal, and it certainly comes close to being ideal, but you face challenges when you produce Internet videos. You need to know about factors that present difficulties throughout the creation process, and about how NT addresses these factors. I'll show you how to adjust a video file so that it will travel across the Internet effectively. Along the way, I'll define several terms and practices of the Internet video trade, and the sidebar "Internet Video Terms" (page 198) provides additional definitions.

Begin with the End in Mind
The adage that you need to begin with the end in mind has never been truer than it is for Internet video. If you don't know what level of audio and visual quality your video requires, you can't make the decisions that are necessary to achieve that quality. And the principle of garbage in, garbage out means that adding quality to your Internet video entails adding cost. So your first challenge is balancing your desire for quality with the need to manage costs.

Every videographer must ask, "How good is good enough?" For example, if your videotape is primarily for TV viewing through a VCR, its picture quality must be higher than it has to be if you intend to send the same video across the Internet. If you want to release your video in different formats (e.g., videotape, CD-ROM, and Internet video), the quality of the base product will have to be the best possible in order to translate successfully and uniformly to other formats. The constraints of the format you choose will force you to make decisions about quality and will either enhance or limit your production options.

Video on the Internet is a challenging format. Most of the challenge relates to bandwidth. Because the Internet experiences frequent traffic congestion, you'll only add to the overall problem if you send too much data. The solution is to send as little data as possible, yet maintain the production quality of your video.

Three things matter the most in the production quality of an Internet video: frame rate, compression routines, and playback size. One frame of video at 176 * 144 resolution contains 25,344 pixels that must be transferred across the Internet, be processed by the receiving computer, and then be transferred through the video card before the monitor can display the image. A 320 * 240 frame has 76,800 pixels, more than three times as many pixels as the 176 * 144 frame. If you want your video to display optimally for the viewer, then depending on bandwidth constraints, you must either lower the frame and bit rates, use powerful compression routines, limit the size of the playback (i.e., go with 176 * 144 resolution instead of 320 * 240 resolution), or do all three. This balancing act can be difficult when the quality of your video is at stake. (Table 1, page 199, provides some tips to help you improve the quality of your Internet videos.)

Frame Rate and Bit Rate:
The Building Blocks of Video Production
The most basic way to deal with the bandwidth challenge is to manipulate the frame rate of your video. You measure video frame rate in number of frames per second (fps). Television in the United States, Canada, and Japan is NTSC standard and runs at 30fps. Television in the rest of the world uses PAL and runs at 25fps. On the desktop, frame rates as high as 25fps or 30fps aren't feasible because they use too much bandwidth and require excessive processing by the receiving computer. Therefore, most video on the Internet is between 2fps and 15fps. On a standard computer monitor, viewers perceive little difference in picture quality between 15fps and 30fps, so 15fps is usually the maximum used for Internet video. For head-and-shoulders (talking heads) shots, 10fps works well, but sometimes a computer has difficulty processing 10fps on the desktop and might drop frames erratically. Video at 5fps resembles dubbed movies in which an actor's lips don't move in sync with the sound. Video at 2fps is like a slide show.

Internet videographers routinely split total available bandwidth between the video and audio portions of a video production. The rule of thumb is that audio is more important than video, so experienced videographers generally give the highest bandwidth priority to audio. In fact, for audio, videographers sometimes reduce frame rate if bandwidth is insufficient (because of connection constraints or other limitations) to maintain the necessary data transfer rate. For example, I had a client who wanted to demonstrate his handmade violins on the Internet. To preserve enough bandwidth for CD-quality sound, I used 2fps in the video I produced for him.

Bit rate, the speed at which binary coded data transmits, determines how well your video transfers through viewers' modems to their monitors. If the modem connection is fast, it will transmit a video with either high or low bit rates. But a slow connection can't transfer all the data from a high-bit-rate video, and the quality of the playback will therefore be erratic. To maximize quality objectives, Internet videographers must adjust their video productions' bit rates in combination with the frame rates. (I'll show you how this adjustment works shortly.)

Codec Is Key
The need to compress your Internet video before you transmit it is a significant challenge, especially when you consider that a 500MB video file contains only about 45 seconds of uncompressed video. Here is where a powerful codec can save the day. Codec is short for compressor/decompressor. A codec is a compression algorithm packaged for use in a specific platform and file format. The most powerful codec I've heard about can generate a compression ratio of 1000:1 (RealNetworks, formerly Progressive Networks, developed this codec). The codec compresses digital data when it finds repeatable patterns in the binary code and replaces those patterns with a code that is much smaller than the original patterns. If a video has a lot of movement, the binary code has fewer repeatable patterns, and therefore the codec can't compress the video to as great a degree as it can a video with less movement.

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