• MS Video 1 (MS-CRAM)
• Supermac Cinepak
• Microsoft RLE
• Intel Indeo R2.1/Raw
• Intel Indeo R2.1/YVU9)
• Intel Indeo R3.1 (IV31)
• Intel Indeo R3.2 (IV32)
• Intel Indeo Interactive 4.1

QuickTime is a video format from Apple Computer, Inc. that provides a common multi-platform video format that includes video and audio codecs for high quality playback and authoring. Several of the common video codecs such as Cinepak, and JPEG, can be used in content played back in a QuickTime format. QuickTime provides two software codecs for video, a video compressor and a compact video compressor. These codecs compress and decompress video running on computers using Apple's Macintosh operating system and Microsoft's Windows-based operating systems.

Note: In the context of this discussion of codecs, bit rate refers to approximate network data rates of:

• Low < 40 Kbps or lower
• Medium 50 to 150 Kbps
• High > than 150 Kbps

These audio and video codecs are examples of common software compression and decompression solutions. Most of these codecs are available through various software applications, such as video editing and audio editing packages, or directly from the developer of the codec. This list is for reference purposes only and is not meant to be comprehensive or a comparison of the quality and performance of the various codecs.

Other codecs will obviously be developed as demand for the "magic codec" that can improve data quality while providing a fast network delivery increases rapidly.

More is always better...memory, disk space, processor speed, video speed, and so on! The processes involved in creating video and audio puts huge demands on the hardware to rapidly and accurately move large amounts of information to the computer. You quickly find yourself spending more time waiting than working if the hardware is not up to this. While no single list of hardware requirements is the ultimate answer because of unique needs and ever changing hardware availability, the following hardware components are representative of an efficient multimedia creation system regardless of the platform type. This list represents hardware for general multimedia creation, not for the creation of Microsoft NetShow specific content, which will be addressed in other sections.

Software, like hardware, is continuously changing and improving, and the specific requirements of each content producer likely differ. If you intend to work with images, audio, and video, however, certain categories of software are necessities. This list is meant to be representative of some of the software useful in developing images, audio, video, and animation media elements.

Two of the first questions you should ask when confronted with developing new images or re-purposing existing images for a multimedia project are:

• What will be the delivery mechanism for the images?
• Will the images be displayed on Web pages delivered over a dial-in modem, over a high-speed corporate network, from a CD-ROM drive, or from a user's local hard disk?

These questions are vital, since they determine many of the required characteristics of the images, such as color depth, color palette, how large the image is in size, and in what file format the image should be saved. All these factors determine how quickly a user receives an image, how quickly the image is displayed on the user's screen, and how good the quality of the image is. The answers to these questions lie in the concepts of bandwidth and data rate.

Bandwidth can be defined as the amount of information a phone line, network, or other delivery mechanism can transmit in a certain time period. For example, a 28.8 modem connection refers to the ability to transmit and receive 28,800 bits of data/information per second (28.8 Kbps), while a high-speed local area network in a corporation might be able to carry 10 million bits of data per second (10 Mbps). Data rate in the context of this section refers to the amount of data or bits transmitted in a certain time period, usually expressed as kilobits per second (Kbps), Kilobytes per second (Kbps), or Megabits per second (Mbps). This table gives an idea of the image size at different color depths and screen resolutions.

Two major sources determine where you'll get your images: existing images and newly created images.

Existing images include artwork obtained from clip-art packages, stock photo art, or any other image that already exists in digital form. Working with images that already exist, commonly referred to as "re-purposing an image," generally involves four main activities:

• Obtaining the image in digital form.
• Resizing.
• Color-palette manipulation for Web delivery.
• Converting the file format for Web delivery.

If the image requires editing to change its visual quality and appearance, these steps generally are the same as those used on newly created images.

Does an image that is to be captured exist in an analog form, or is the image to be created entirely in a digital domain? The answer to this question determines your next steps.

Digital: The creation of new digital images can be accomplished in two main ways:

(1) A graphic designer using image editing type of software.

(2) The image is captured with a digital camera or image scanner and transferred to the computer for manipulation with image editing software.

Analog: If the image exists in analog form, the equipment used to capture the image is generally the same as that used for capturing video images, which is covered in more detail under the Video section. In summary, however, the most common source of images in an analog form is videotape. Using a variety of video or still-image capture hardware, specific images are converted to digital form and transferred to the computer for storage and later editing.

Understanding file formats is an important part of working with images. A variety of file formats have been created to serve various needs. Some file formats are optimized for high image quality or ease of editing and scaling to various sizes, while other formats are optimized for small size and rapid display on a computer monitor. As discussed earlier in Planning, knowing how the image is to be delivered can easily solve most of the issues related to the different file formats.

Generally, if the image is to be displayed within a browser, the choices are limited to JPEG, GIF, BMP, and more recently, PNG. However, this selection is likely to change rapidly as other technologies, such as MacroMedia's Shockwave for Freehand allow additional file formats to be delivered within a Web browser. Even with this limited number of choices for Internet delivery, it is important to have a basic understanding of the features of each image type.

Three types of images are commonly referenced when talking about file formats:

• raster, or "bitmap/paint" type images
• vector, or "draw" images
• metafiles

Bitmap or raster images are made up of a series of pixels, each having distinct properties such as the color depth and pixel color. If a bitmap image is enlarged, you see a series of pixels, each of which can be edited with the appropriate image editing software. Because a bitmap image is made up of individual pixels, certain characteristics are associated with a bitmap:

• The image generally does not scale well (the pixels get pulled apart or squeezed together).
• The file size for a bitmap is larger than a vector or draw image.
• The print output of a bitmap image may not be high quality.
• Many compression schemes are applied to bitmap images to make the image smaller.
• Special effects are easy to do with bitmap images, as each pixel can be independently altered.

Vector, or "draw" images are made up of a series of lines that are stored as mathematical functions rather than individual pixels. If you enlarge a vector image you do not see individual pixels, only a line representation of the image. Only recently are software packages being developed that allow some of the special effects commonly associated with bitmap images. Vector images have unique characteristics compared to bitmap images.

• The image scales very well.
• The images print at extremely high quality.
• The file size is very small in comparison to a bitmap.
• More specialized software is required to edit vector/draw images.

Metafiles are a combination of vector and bitmap components that attempt to capture the advantages of each format (primarily the output advantages and small file size of vector files and the on-screen display quality of bitmap images).

Depending on your hardware requirements and budget, you can obtain nearly any level of image production and editing functionality. There are software packages in the freeware and shareware domain that are available for free or for only a small cost, as well as professional graphics packages costing thousands of dollars and requiring dedicated hardware. This section will not cover the high-end graphic and hardware solutions generally sold as packaged bundles or for professional production purposes.

This content creation scenario is an overview of the planning and processes that go into creating a new image. It is not meant to be comprehensive, nor is it a tutorial on individual software packages. Consult the documentation for your specific software package if you need help on detailed usage. This scenario briefly presents the processes involved in several separate production areas. Many different tools are available to do this work; we've told the story behind just one way of creating a new image. The example covers:

1) New image creation

2) Image Editing - Special effects

3) Image Utilities

(a) Image sizing and cropping

(b) Color palette manipulation

(c) File format conversion

Oh great, they need this logo by Friday in order to get it ready for the printer and implemented into the Web pages; good luck! This type of work always takes much more time than we have...we get agreement on the message, and then comes the hard stuff; getting buyoff on the colors, the size, the overall presentations, that "look-and-feel stuff," and on and on.

10:30 A.M. Thursday:

One key point I want to make here is the similarity between many of the steps I just went through when creating a new image and what I would have done if the image already existed. In fact, many times you'll use existing and new images and composite them to get the look you want.

As discussed earlier, there are two common methods of acquiring images; creation of new images and the re-purposing of existing images. It is becoming much easier to obtain existing images; professional stock photo services license and sell literally thousands of images in all common file formats. There is also a huge repository of public-domain images that can generally be used without licensing issues. For example, many of the materials the United States government produces are in the public domain, and numerous image public-domain libraries exist on the Internet. However, it is not always easy to be certain that a multimedia element is in the public domain.

Generally, if you produce your own new content or hire a professional design service to do the work for you, you will own the copyright to your creations and can use them as you wish. With the increasing availability of scanners and digital cameras, it is becoming very easy to "create" new images. However, remember that just because you go to the trouble of scanning an image or taking a digital picture doesn't mean you have legal right to that image. For example, you generally should get a legal release from anyone who appears in your pictures. You can't just take someone's picture and use it!

Numerous legal issues exist when dealing with any multimedia element, be it images, audio, video, or animation. This discussion is not meant to be a comprehensive coverage of legal issues. nor is it intended to provide legal advice; use the information only as a guideline for some of the issues you should be aware of when you're using existing media elements.

In order to use existing content in your multimedia project, three general types of arrangements are possible.

How the content is to be used or altered has an impact on the legal steps you'll need to take to use the media. Permission letters or release forms signed by the owner of the copyright might suffice if the media is to be used unaltered. If you plan on editing the media, a more comprehensive legal agreement may be necessary. Either way, legal advice is important before you find out that one of the parties interested in your multimedia creation is interested for reasons other than your artistic creativity!

Some states have laws against using any person's name and likeness (for example, a photograph) for commercial purposes without prior written consent. "Commercial purposes" usually doesn't just mean selling your multimedia product; it also means promoting any of your company's products. It is wise, if not legally required depending on the state where you reside, to get a signed release from the company and individual if you use any image that is identifiable as that person or company.

This can be a complex area, since your multimedia project may appear to promote or sponsor a trademarked product or media element. Again, it is important to gain legal advice before using any content that is clearly associated with another company's image or product line.

You should ask the same types of questions when you're working with audio and video as you did with images:

• What will be the delivery mechanism for the audio?
• Will the audio be played from Web pages delivered over a dial-in modem, over a high speed corporate network, from a CD-ROM drive, or from a user's local hard disk?

Again, the answers to these questions are to be found in the concepts of bandwidth and data rate. These questions guide you in determining many of the characteristics of the audio that you will work with, such as the sampling rate, the overall quality of the audio, and whether the audio is mono or stereo. All of these factors determine how quickly a user hears the audio after their request and how good the quality of the audio is once they hear it.

As discussed in other sections, bandwidth is defined as the amount of information a network can carry in a certain time period. For example, a 28.8 modem connection refers to the ability to transmit and receive 28,800 bits of data/information per second (28.8 Kbps), while a high-speed local area network in a corporation might be able to carry 10 million bits (10 Mbps) or more of data per second. Data rate in the context of this section refers to the amount of data or bits transmitted in a certain time period and is usually expressed as KB Kilobytes (KB), Kilobits (Kb), Megabits (Mb), or Megabytes (MB). This table gives an idea of the amount of audio data associated with different perceived qualities of sound.

You've heard this story before; two major sources determine where you'll get your audio content; existing audio and newly created audio.

Existing audio includes sound clips from "sound clip" packages, stock photo art, or any other audio clip that already exists in digital form. Working with audio that already exists generally involves five main activities:

• Obtaining the audio in digital form.
• Normalizing the audio track.
• Editing the audio for effects (optional).
• Compressing the audio track.
• Converting the file format for Web delivery.

If the audio requires editing to change the audio quality and fidelity, these steps generally are the same as those used on newly created audio material.

Digital: The creation of new digital audio material can be summarized as:

Capturing audio directly to the computer through audio recording software and a microphone. In this process, the audio is never stored in an analog form that requires conversion to digital.

Using music creation software to create musical pieces for themes, background music, and so on. Generally, these are much longer pieces and involve first steps using MIDI file formats or other specialized audio formats. At some point following creation, the audio files may be converted to .wav for use in multiple Internet browsers for compatibility.

Analog: If the audio exists in analog form, the equipment used to record the audio is generally the same as that used for playback and recording of digital audio on your computer: a multimedia sound board. The most common source analog audio is videotape or a cassette recording. Using a variety of audio recording hardware, audio clips are converted to digital form and are directly transferred to the computer for storage and later editing.

This list of audio recording hardware is by no means comprehensive, nor does it recommend any specific component. It is meant to give a representative range of equipment offerings available for recording and playing back audio.

The amount of change in air pressure is perceived as loudness; no change equals silence, while the more pressure, the louder the sound. The technical term for loudness is amplitude and the unit of measure is decibel. A reference point for "normal" sound is 0 dB; negative numbers represent a lower volume, while positive numbers represent more loudness.

The rate at which the sound wave changes is perceived as pitch, or what we think of as how high or low the tone is. The more technical term for pitch or the rate of the sound wave is frequency, commonly expressed as cycles per second or hertz (Hz). For example, the range of human hearing is generally said to be between 20 to 16-20,000 Hz. An audio system's bandwidth is its ability to reproduce a range of sound frequencies.

Different types of sounds have varying bandwidths; for example, speech is generally between 200 Hz and 5,000 Hz, while a full, rich audio CD will have a much wider bandwidth, possibly encompassing nearly the entire audible range.

Graphically, a sound wave looks like:

Ok, what does this have to do with creating audio for multimedia use? When you record or edit audio files, you'll see references to sample frequency, audio bandwidth, and sampling rate. Also, recording and editing processes with computers are based on digital rather than analog sound. Having a general understanding of what these terms mean gives you a better chance of getting the quality of audio that best fits your needs.

Several different file formats exist for audio files. These formats can be conveniently divided into two categories: a digital format such as .wav, and music "information" files known as MIDI. Wave files are digital files that are commonly used for sound effects, sound clips, voice, and recorded music. MIDI, which stands for Musical Instrument Digital Interface files, are not sampled sounds in a digital form, but rather computer-synthesized sounds. MIDI sounds are a set of instructions that reproduce the pitch, tone, and duration of a sound. MIDI files are much smaller than digitized files such as .wav, but require more complex software and hardware for recording and playback.

Only a small discussion of MIDI is given in this section. Many excellent references exist if you are interested in this type of audio. MIDI is not actually a sound, but rather a control for electronic musical instruments such as synthesizers and drum machines. A .mid audio file is simply another type of digital data that can be stored, edited, and replayed from a computer.

MIDI format is not supported in Windows or Macintosh video files (.avi and .mov, respectively). Currently only Microsoft's Internet Explorer version 3.0 or later supports .mid files as a source of audio in a browser. So at this point, let's move on.

Recording audio sounds or digitizing audio is usually one of two processes:

1. Analog audio is captured (commonly referred to as sampled ) and is then converted to digital form.
2. Audio is sampled with digital equipment and no conversion to digital form is required.

In either case, the audio signal can be recorded and converted to a stereo or mono audio track. One important point is that if the original audio is not in stereo, saving the file as stereo doesn't make for a true stereo experience. Granted, the way the original stereo file was recorded and mixed has a great impact on it's stereo sound quality. However, merely splitting a mono file into two sound tracks to make it stereo is not the same as creating a quality, mixed stereo file.

When an analog audio file is digitized or sampled, two properties of the analog audio are recorded; the amplitude, or loudness of the audio, and the timespan of the audio signal. When audio is sampled, instantaneous recordings of the sound wave are made over time. The number of samples taken per second is referred to as the sampling rate. The sampling rate MUST be at least two times the highest audio frequency to be reproduced. Now here's where those things called "hertz" become real!

If you are to reproduce audio frequencies up to 10,000 Hz (10 kHz), a sampling rate of at least 20,000 (20 kHz) is required. Most sound recording boards for computers have the capability of recording sound at various sampling rates, generally 8 kHz, 11 kHz, 22 kHz, and 44.1 kHz. One trade-off of sampling at a high rate is sample size; the more samples you take per second, the larger the size of the audio file.

Now that a series of individual sampling points have been based on the sampling rate, one more step is required before we have a true digital audio sample. This step is referred to as quantization. Think of each individual sampling as having a number of levels or "richness". Sound recording boards are either 8-bit or 16-bit. This means that if audio is recorded as 8-bit sound, then there are 256 levels of richness. If the audio is recorded as 16-bit sound, the number of levels of richness increases to 65,536.

This means that a sound recorded as 16-bit audio has 256 times the amount of information as the same sound recorded as 8-bit audio. The overall quality of a 16-bit recording over an 8-bit one is very noticeable; the human ear is very sensitive to sound quality! This is a key point when recording audio; always record at the highest quality possible for your source material. You can always degrade an audio sample, but you can't make it better than what you started with. If you can get 44.1 kHz, 16-bit audio samples as your source material, do it. Everything will sound much better after you start editing and compressing the sounds later.

As presented earlier in this audio section, audio files can get quite large depending on their sample rate (frequency), the number of bits per sample (in other words, their perceived quality or richness), and whether they are stereo or mono. For example, a 22kHz, 16 bit mono music sample can require a data rate of 2.65 MB per minute to hear it as it was intended when it was digitized. The key to playing audio files over a network of limited bandwidth or storing audio files on a computer hard disk is compression with codecs. Many codecs exist for differing audio needs. Some codecs are optimized for voice, while others are best suited to low-to-high-bit-rate music samples. This list of codecs is not comprehensive, but provides a summary of the commonly used audio codecs in multimedia content.

Just as with images and video, depending on your hardware requirements and budget, you can produce a range of sounds from beeps and clicks to full musical scores. You can find audio software as freeware or shareware, or you can pay thousands of dollars to get professional audio recording and editing capabilities. This section will not cover high-end professional audio production.

This content creation scenario is an overview of the planning and processes that go into creating a new audio clip. It is not meant to be comprehensive, nor is it a tutorial on individual software packages. Consult the documentation for your specific software package if you need help on detailed usage. This scenario briefly presents the processes involved in several separate production areas. Many different tools are available to do this work; I've told the story behind just one way of creating a new image. The example covers:

• Recording a new sound from videotape
• Audio editing
• Audio file preparation

Several months ago, the company I work for made a video for Human Resources recruitment efforts. For this video, a professional music sound track was created. The project I'm working on right now is to develop an illustrated audio using NetShow; you can learn all about this by checking out the section on Creating Illustrated Audio using NetShow in the NetShow Content Creation Authoring Guide. Simply put, illustrated audio is a synchronized audio track with images, text captions like closed captioning on TV, and, if desired, different VB Script or JavaScript features, depending on how much scripting you want to do.

1. I already have the images I'll use; I just need some cool background music to listen to during various parts of the presentation. The sound track on our recruitment video would be exactly what I'm looking for. I just have to figure out what I actually need for the illustrated audio project and then how I get the audio from videotape to the format I need.
2. First, I have to determine what type of audio file I need for the final presentation, the browser, and the bandwidth of the network over which the content will be played. The browser and bandwidth issues are easy; this is for internal use in our company and IE 3 is our corporate standard. The network issue is determined for me; our information services group allows delivery of content up to 100 Kbps. The NetShow server acts as a gateway for this point; the server can be set up by an administrator to deliver content only if it is less than a predetermined data rate.
3. Because the audio track is on videotape, I have to digitize it from the tape source. This can be done in two general ways, one being much better than the other. The first way is to merely play the videotape and record the sound using a microphone plugged into my sound card. Sure, this is easy, but the quality would be terrible. I'd get too much background noise from the air conditioner, people talking in the hall, and so on. So that's not a viable option.
4. The other method, and the one I'll use, is to record the audio directly from the videotape into the sound card. This way I get a sample as close to the original as possible using a standard computer sound card and a VHS tape deck.
5. I won't go into the exact cable hookups between the VCR and the sound card, but basically the left and right audio-out terminals on the VCR are connected to the line-in or microphone terminal on the sound card. The next step of setting up and balancing the recording volume actually is the best determining factor for which sound card connection to use.
6. Balancing your recording levels means optimizing the recording volumes so that you get the highest possible distortion-free volume without getting extraneous background noise from other devices.
7. Open the Properties dialog box for the sound card in your machine and select the recording properties. This should display the master volume recording panel. Some trial and error is involved, so for starters, place the master volume level at mid-range and set the line-in or microphone level near the maximum setting.
8. You might see other devices such as, CD-ROM or Synthesizer (MIDI), in the recording panel. Mute all non-essential devices; this cuts down feedback and background noise.
9. Now open the sound recording program that you'll be using. One of the simplest is Sound Recorder, which comes with the accessories when Windows is installed. More sophisticated sound recording packages, such as Sound Forge from Sonic Foundry, should be used if you want to record very long pieces of audio. Sound Recorder records the audio to the memory (RAM) of your computer, so unless you have LOTS of RAM you'll only be able to record short audio clips. Look for an audio recording and editing package that allows you to record to disk so that you can capture much larger pieces of audio.
10. Start the playback of the VCR and select the Record button in your sound recording program. You should see a wave pattern display of the audio as it is playing. What you want to do to balance your recording volume is look for the highs and lows of the audio as it is being recorded. If the volume settings are too high, you see the wave patterns being clipped off and appearing to fill the recording window. If the settings are too low, you see only very small variations in the wave pattern.
11. If the sound is being clipped off because the volume is too high, move the line-in or microphone volume setting down until most of the volume range is displayed without clipping.
12. If the sound is too low, increase the volume setting. Ok, here's the trick with the line-in or microphone input. Depending on your sound card and the volume of the audio source, you might not get enough volume using the line-in input. In this case try the microphone input, as the volume sensitivity through the microphone input is generally greater than with the line-in input.
13. I only had to make minor volume adjustments with this audio source. Generally, if the audio has been professionally recorded, part of the recording process is to balance the source and get maximum volume with minimal distortion. This simplifies the recording process on my side, as I don't have to try and adjust for wide swings in volume. Keep this point in mind when you're recording audio that will be source material for some future work.
14. In my sound recording program, set the recording options for the highest-quality sound possible; with most sound boards this is 44.1 kHz, 16-bit stereo sound. I'll need to change this for the audio used in the illustrated audio, because this high-quality audio would be far too large to deliver over our corporate network, not to mention the Internet bandwidth.
15. OK, let's rewind the tape and start the playback from the point I want to record. Hit the record button and stand by. When finished recording, save the file immediately. Remember the last time you'd didn't save the file?
16. In the Save dialog box, many different options are available depending on what codecs I've installed previously. At this point, I want to keep the audio as high-quality as possible. I'll select the uncompressed attribute, which saves the file as PCM, with the same options used for the recording. In this case, 44.1 kHz, 16-bit audio.
17. Now that I have my digital source file, I need to do some editing and then compress the file into a final delivery format. I'm going to use Sound Forge to edit and compress my file. So I reopen the file and first play it back to see that it sounds like I expect it to.
18. There are a few clicks, pops, and other artifact noises that I want to get rid of. Sound Forge and some other robust audio editing tools have the capabilities to analyze the audio file and remove extraneous noise. After I've done this and put a fade in and fade out at the beginning and ending, I'm ready to compress the file and degrade it to a bandwidth closer to what I'll need in the final piece.
19. I save the file as a 22 kHz, 16-bit stereo using the MS ASPCM codec. This does some compression, but retains very high-quality sound. The file is probably still too large for my illustrated audio, but I'll use the ASF Editor for final determination of a codec. If you'd like to get more information on the ASF Editor, take a look at the Content Creation Authoring Guide section on Creating Illustrated Audio or refer to the documentation on the ASF Editor that is available when you download the NetShow tools.
20. The audio file is basically ready for use in a specific project, so I'll move on to the next steps of making the illustrated audio. Talk with you later.

As discussed earlier, there are two common methods of acquiring audio; creation of new sounds and the use of existing sound material. It is becoming much easier to obtain existing audio clips; professional audio services license and sell literally thousands of sound clips in all common file formats. There is also a huge repository of public-domain audio that can generally be used without having to deal with licensing issues. For example, many sites on the Web have free sound clips that can be used in your multimedia projects.

However, it is MUCH harder to get complete audio pieces such as music. Most music is created and composed for commercial purposes and this immediately makes the legal issues much more complex, or at least much more expensive.

Generally, if you produce your own new content or hire a professional design service to do the work for you, you will own the copyright to your creations and can use them as you wish. With the increasing availability of high-quality audio recorders, it is becoming very easy to "record" new audio material. However, remember that just because you go to the trouble, for example, of recording an interview conducted personally, or recording a concert or a movie or TV sound track, this doesn't mean you have the legal right to use that recording. For example, you should get a legal release from anyone who can be identified in your recordings and get legal permission before using any commercial presentations. This type of media has strict copyrights to prevent this kind of use and distribution.

Remember that the legal issues involved in dealing with any multimedia content that you do not own are complex. This discussion is not meant to be a comprehensive coverage of legal issues nor is it indended to provide legal advice; use the information only as a guideline for some of the issues you should be aware of when you're using existing media elements.

In order to use existing content in your multimedia project, three general types of arrangements are possible.

How the content is to be used or altered has an impact on the legal steps you'll need to take to use the media. Permission letters or release forms signed by the owner of the copyright might suffice if the media is to be used unaltered. If you plan on editing the media, a more comprehensive legal agreement may be necessary. Either way, legal advice is important before you find out that one of the parties interested in your multimedia creation is interested for reasons other than your artistic creativity!

Some states have laws against using any person's name and likeness, such as their voice, for commercial purposes without prior written consent. "Commercial purposes" usually doesn't mean selling just your multimedia project; it also means promoting any of your company's products. It is wise, if not legally required depending on the state where you reside, to get a signed release from the company and individual if you use any image that is identifiable as that person or company.

This can be a complex area, since your multimedia project may appear to promote or sponsor a trademarked product or media element. Again, it is important to gain legal advice before using any content that is clearly associated with another company's image or product line.

Before we start discussing the processes involved in creating video, a "quick and dirty" definition of video is in order. A key factor in what is perceived as video is the frames rate or frames per second (fps). The human eye is very sensitive to motion. Below about 8 fps, motion is generally seen as varying degrees of jerky slide shows. However, depending on the type of scenes and motion between scenes, there is some variation in the fps and the interpretation as video. Sometimes this is not as obvious as it seems!

For example, a close-up video of a person, commonly referred to as a "talking head," might seem to allow for a lower frame rate and still look like video because there isn't as much going on in each scene. However, when the human eye has fewer moving details to focus on and these details are largely associated with mouth movement and the synchronization of audio, watch out. The end result is often interpreted as very poor video because the lip synch with the audio is poor. Other factors, such as how close the camera is, how stable it is, and how many head movements the person is making, all impact the final video outcome.

Compare this to the fast-paced "MTV-like or sports" video that has rapid cuts to different scenes and no voice synchronization, and often high-motion video such as this can be reduced as much or more in frame rate and still be acceptable. The eye doesn't have as many details to focus on, the scenes are often presented in a jerky succession anyway, and the audio is not synchronized to lip movements. These factors make the end result look better than one might think when considering just the frame rate.

So there is still a degree of "black magic" associated with creating great-looking video. These issues and more are discussed in greater detail in the video section of Multimedia Basics and in the Creating NetShow Video section of this Web site.

When working with video, the initial planning questions are the same as for images or audio:

• What will be the delivery mechanism for the video?
• "Will the video be played from Web pages delivered over a dial-in modem, over a high speed corporate network, from a CD-ROM drive, or from a user's local hard disk?"

Determining the answers to these questions turns out to be related to bandwidth and data-rate issues similar to those encountered when working with audio. These questions guide you in determining many of the characteristics of the video, such as frame rate, data rate, frame size, and codec selection. These factors determine how quickly you see the video, the video quality, and the synchronization of audio to the video stream.

As discussed in other sections, bandwidth is defined as the amount of information a network can carry in a certain time period. For example, a 28.8 modem connection refers to the ability to transmit and receive 28,800 bits of data/information per second (28.8 Kbps), while a high-speed local area network in a corporation might be able to carry 10 million bits (10 Mbps) or more of data per second. Data rate in the context of this section refers to the amount of data or bits transmitted in a certain time period and usually expressed as Kilobits (Kb), Kilobytes (KB) Megabits (Mb), or Megabytes (MB). This table gives an idea of the amount of video data associated with different sizes and frame rates of video.

These video window sizes are used for example purposes only; once you start working with different video codecs you'll find that your final choice for a window size depends on your objectives for the content, an understanding of your audience, and the codec selected for preparation of the video file. The major point is that video requires huge amounts of data to be transferred even when targeting very small frame sizes. The goals of effective video production are to understand how the balance of video quality and data rates are related and to develop a process that optimizes the video quality at the targeted data rate.

Once the issues are understood for determining how fast the video will be delivered to the user, the content creator must consider the user's (client's) hardware and software capabilities. For example, the computer operating system, the type and version of Internet browser, and the graphic and video capabilities of the video card in the user's computer determine the overall video quality displayed to the user.

You've heard this story before; just like with audio, two major sources determine where you'll get your video content; existing video and newly created video.

Existing video includes clips from "video clip" packages, stock video collections, or any other video clip that already exists in digital form. Working with video that already exists generally involves five main activities:

1. Obtaining the video in digital form.
2. Editing the video for frame rate, frame size, and start and end points.
3. Editing the video for effects (optional).
4. Compressing the video track.
5. Converting the file format for Web delivery.

If you have read the Multimedia Basics section "Creating Audio," you will quickly notice the similarity between the planning processes for audio and video. In fact, most of the time when working with video, you have an associated audio component. A good way to think of video is as a combination of three elements, (images, audio, and video). Video is a superset of concepts and processes used with images and audio.

Digital: The creation of new digital video material can be summarized as:

Capturing video directly to the computer using a digital video camera. In this process the video is never stored in an analog form that requires conversion to digital.

Using animation software such as MacroMedia's Director or Flash that allows the synchronization of multiple images along a timeline and path and then the final output as a digital video file such as an .avi or QuickTime .mov file.

Analog: If the video exists in analog form, special video capture equipment is required. In most cases this is a video capture card that is installed in a computer. The most common source of analog video is videotape, either in VHS or S-VHS format. Other videotape formats such as Hi-8 or Beta-SP are sometimes used. Another source of analog video is directly capturing a television signal such as NTSC, PAL, or SECAM.

The term "video production" has a definitional problem! Are we referring to something analogous to Hollywood's movie production or are we talking about producing video in digital form for use on a computer? We'll address both of these scenarios since they are, from the perspective of this discussion, portions of an overall process of creating, capturing, or digitizing video for use in a computer-based environment. Whether you are creating, capturing, or digitizing video, two processes are likely to be involved:

In either case, the video signal is ultimately stored as a pure digital signal for editing and output using a computer and a variety of software applications.

Several different file formats exist for working with digital video files on a computer. These formats can be conveniently divided into three categories; streaming digital video files (.asf), digital video files (.avi and .mov), and hardware-based video files (.mpg). ASF files are digital files that are used to deliver streaming video using Microsoft's NetShow server and client player. The primary advantage of this file format is that the file doesn't have to be downloaded to your computer and the file can start playing without downloading it to your hard disk. AVI and MOV are currently the most common digital video file formats. MPG is a file format based on a hardware-dependent compression scheme.

Have you ever wanted to make movies like Steven Spielberg? Well, maybe you won't have millions of dollars to spend on your next video project, but some of the ideas we'll discuss next are part of a Hollywood director's vocabulary.

Just how involved you'll be in the actual filming process depends on the size of the team you can assemble, the equipment you have available, and the amount of time and money you can spend. Regardless of whether you hire others to do most of the work by a video film group or you work with a one or two person team, knowing something about the concepts and processes involved in producing new analog video will prove to be useful to any video project.

The actual process of recording the video or "shots" isn't as simple as merely taking a camera and shooting the scenes you want. Shooting video is a complex process made up of many components. The foundations for shooting video are camera angle, camera movement, and composition.

Camera angle is the position of the camera, which gives the viewpoint or perspective of the story to be presented by the video. The video should have a frame or visual area in which the important action occurs. A common rule is to mentally divide the visual area up into 9 equal rectangles. Then align the action at one of the four intersections. This provides a visual reference point for action, making it easier for the viewer to keep focused on the action and as you'll see later, helps keep the amount of camera motion to a minimum. This point is important later when you have to be concerned about the overall motion in a scene and how the effectively the codecs interpret this motion.

Camera movement is a very important point when shooting video for compression into low or medium data rates. The details of codec selection are discussed in the following section, "Compression and Storage." Suffice it for now to say that the movements of all objects within a video scene, whether intentional or unintentional, impact the overall video compression.

However, camera movement might be a vital part of the video shoot; so let's cover some of the important types of camera movements and when to use or not use them. One of the most common mistakes in shooting video is allowing excess movement, be it intentional or unintentional. Intentional movement, while planned, might actually detract from the video content. For example, the viewer could have a hard time focusing on the main point of the video shot, or you might find that the video can't be efficiently compressed because of the way the codec interprets motion. This topic is discussed in more detail in the "Video Codec" section later in this article. Unintentional motion is defined here as movement resulting from an unstable camera, such as when you're holding the camera and walking.

If I were to give just one suggestion for shooting video, it would be to use a tripod for the camera. Even though some newer consumer video cameras have "auto-stabilizing" capabilities, there is only so much they can do to counteract the "jittery hand-held camera." If you can't use a tripod, try to position the camera on some stable object, such as against a wall or on a table.

An overview of commonly used camera movements in video recording is:

Panning

The camera remains stationary and follows the action horizontally. This technique is used in presenting a panorama of a landscape.

Tracking

The camera moves on a horizontal plane across the scene following the action.

Tilting

The camera remains stationary but moves up and down (for example, when showing the height of a tall tree).

Craneing

The camera moves vertically following the action.

Zooming

The camera remains stationary, but an object you are focused on increases and decreases in size. A common example is when a scene with a person in it "zooms" in to show a close-up of the person's head.

Dollying

The camera moves in and out from the scene (for example, if the video is taken from the perspective of a person walking down a trail).

The important point to realize in all these camera movements is exactly that-movement. Anytime the individual frames of video are changing their perspective, in addition to motion occurring in the scene itself, the complexity is greatly increased. This increased scene complexity makes it much more difficult to compress the video into a high-quality, low or medium bit rate.

Composition is closely associated with camera movement. Composition in the context of this discussion refers to the ratio between the amount of action and the overall view or size of the scene. For example, if the key action in a scene is a person standing in front of fountain and the overall view is from far away, this would be referred to as a long shot. If the person, from head to foot, took up most of the frame, this would be a medium shot. A close-up, as you can guess, is when the person's face fills the frame.

The important point in composition, relative to producing video that works well in a compressed form delivered over a network, is that rapid or numerous changes between different types of shots add to the complexity of a scene.

As discussed earlier, a variety of video capturing and recording devices exist. In this discussion of producing new video, we're focusing on the actual video recording process. Therefore, two main categories of video cameras should be mentioned: analog video cameras and digital video cameras. We will not discuss specific brands and features of either type of video camera; we will mention several points related to quality and ease of use that you should consider in creating a multimedia presentation .

The old saying "garbage in, garbage out" is especially true when producing video for use in multimedia presentations. One of the main keys to great video is great equipment. The money you spend when buying or renting a high-end video camera (rather than just using your consumer camera that's been sitting in the closet) pays off tremendously in the end result. With that said, here are a few guidelines regarding video camera equipment.

Currently, analog video cameras are much more common than digital video cameras. This is likely to change in the future, but for now you're more likely to work in the analog realm while doing video recording. Two general categories of analog cameras are consumer-level and commercial-level. This division is based not so much on cost as it is on quality.

Consumer-level cameras commonly record in VHS or 8mm format. The commercial-level cousins are S-VHS and Hi-8 format, respectively. Even higher-quality commercial cameras use the Beta format. Based on the premise that your video and audio source should be as high quality as possible, the best choices for an analog camera are:

• Betacam
• S-VHS or Hi-8
• VHS or 8-mm

Once you have the video recorded, remember that you still have to go through a conversion to digital form. This requires three important equipment-related items: first, a video player capable of working with your video source format; secondly, the VCR with output connections of the appropriate type for your capture card; and lastly, a video capture card that can accept the video format of your recording. A key point, often overlooked, is that the combination of playback, capture equipment, and video recording format are incompatible. For example, you can record in high quality Beta format, but if your VCR can't play Beta tapes or your capture card doesn't have suitable connections for a Beta VCR, you're in big trouble. In summary, plan, plan, and then plan again!

Using a digital video camera removes many of the issues described above for analog video cameras. First, you don't have to do an analog-to-digital conversion, which can decrease video quality even with the best equipment and processes. Second, you don't have to deal with video format compatibility issues between the camera, video player, and capture card.

Once you have your video, the next steps depend on whether the video is in analog or digital form. If it is already in a digital form, the capture/digitization process, described next, is unnecessary. Your next concern would be the editing and compression steps. However, if you have an analog video source, we have to discuss the capture/digitization process necessary to convert your analog video into digital video.

One of the first steps necessary for digitizing video is getting a video capture card. As with most things in life and, as you're finding out, with multimedia, money plays a big part. In general, video capture boards that are capable of very high-quality video capture cost considerably more than the "consumer-level" video capture boards. To put this in perspective: consumer-level video capture boards can be purchased for a sum ranging from a few hundred dollars up to around $1,000, while the production-level video capture boards can easily run up to $3,000 or $4,000. If you want to go with a dedicated video system for video capture and video editing, be prepared to spend $10,000 or more.

This list of video and image capture hardware is by no means comprehensive, nor does it recommend any specific component. It is meant to give a representative range of equipment costs available for video and image capture. For a more complete list of video capture equipment, see the earlier section in this article.

Several commonly used video capture software packages are:

• Adobe Premiere
• Microsoft VidCap
• Asymetrix Digital Video Producer
• Ulead Systems Media Studio Pro
• Corel Lumiere

After the video stream has been digitized, the main objective is to set the desired frame rate, frame size, and data rate. These factors have direct impact on the success of your delivery. Improper selection of any these video attributes causes quality and bandwidth problems. If the video requires editing such as removing unwanted frames or adding transitions, most video editing packages allow you to do this at the same time that you set the size and the frame and data rates.

Setting these attributes is directly linked to the compression scheme you select. Certain codecs are more effective when, for example, certain frame sizes are selected. VDOWave is optimally designed to work best with 160 x 112 frame sizes, while MPEG-4 allows a much wider selection of frame sizes. Each attribute has its own characteristics that you need to understand in order to select the most effective codec for your content. The next section, "Compression and Storage," should be read carefully to answer many of your questions concerning this production phase.

If you want a general overview of the video capture through editing and conversion process, read the "Sample Content Creation Scenario" section later in this article.

As discussed earlier in other sections, video files can get quite large depending on their frame rate, frame size, and color depth. For example, a 320 x 240, 15-fps video clip captured at 24-bit color can require a data rate of 3.46 MB per second to see and hear it. The key to playing video files over a network of limited bandwidth or storing video files on a computer hard disk is compression with codecs. Many codecs are available for differing video needs. For example, some codecs are optimized for low bit rates, while others are optimized for high bit rates. Others have optimal frame sizes and frame rates. As part of the planning process, it's important to determine what these factors are for your content, and with this understanding you'll be better able to select a codec optimal for your video needs. This list of codecs is not comprehensive, but provides a summary of video codecs commonly used when creating multimedia content.

Note: In the context of this discussion of codecs, bit rate refers to the approximate network data rates of:

• Low < 40 Kbps or lower
• Medium 50 to 150 Kbps
• High > than 150 Kbps

As a point of reference, a 2x CD-ROM drive has a data transfer rate of approximately 300 Kbps or 2.4 MBps; and we think a CD-ROM drive is slow!

The creation of video content is the compilation of work with images, audio, and video. Video creation may involve only video capture and conversion steps, or you might want to do additional video and audio editing. Even basic video creation commonly involves a wide variety of content creation software applications, from image creation and editing, to audio and video creation and editing. This section will not cover high-end professional video production.

This content creation scenario is an overview of the planning and processes that go into creating a new video clip. Just as with the image and audio content creation scenarios, it is not meant to be comprehensive, nor is it a tutorial on individual software packages. Consult the documentation for your specific software package if you need help on detailed usage. This scenario briefly presents the processes involved in producing a video clip. Many different tools are available to do this work; this story tells about one way of creating a new video clip from videotape. The example covers:

• Capturing video from videotape
• Video editing
• Audio editing
• Video file compression

As I described in the image creation scenario, Human Resources recently had produced videotape to help their recruitment efforts. An outside video production company was hired to develop the script, do the actual video shoot, provide the talent, and ultimately deliver a finished videotape in both S-VHS and VHS format. Human Resources wants to use Microsoft NetShow to develop a series of video recruitment clips for the Internet; the creation of these Internet ready video clips is my task. This scenario doesn't describe the details of producing the NetShow delivered content; you can learn more about this by checking out the section on Creating Video using NetShow in the Content Creation Authoring Guide. This section focuses on the steps through the production of the NetShow streaming file format, ASF.

As discussed earlier, there are two common methods of acquiring audio; creation of new sounds and the use of existing sound material. The same issues are relevant when dealing with video acquisition and licensing. It is becoming easier to obtain existing video clips. Professional audio services license and sell thousands of video clips in the common file formats; most often, .avi and .mov (QuickTime). There is also public-domain video that can generally be used without encountering licensing issues. For example, there are numerous companies developing graphic software that offer CDs of free video clips that can be used in your multimedia projects.

A important point to remember; the legal issues involved in dealing with any multimedia content that you do not own are complex. This discussion is not meant to be a comprehensive coverage of legal issues, nor does it attempt to provide legal advice; use the information only as a guideline for some of the issues you should be aware of when you're using existing media elements.

In order to use existing content in your multimedia project, three general types of arrangements are possible.

How the content is to be used or altered has an impact on the legal steps you'll need to take to use the media. Permission letters or release forms signed by the owner of the copyright might suffice if the media is to be used unaltered. If you plan on editing the media, a more comprehensive legal agreement may be necessary. Either way, legal advice is important before you find out that one of the parties interested in your multimedia creation is interested for reasons other than your artistic creativity!

Some states have laws against using any person's name or likeness, such as their voice, for commercial purposes without prior written consent. "Commercial purposes" usually doesn't mean just selling your multimedia product; it alo means promoting any of your company's products. It is wise, if not legally required depending on the state where you reside, to get a signed release from the company and individual if you use any image that is identifiable as that person or company.

This can be a complex area, since your multimedia project may appear to promote or sponsor a trademarked product or media element. Again, it is important to gain legal advice before using any content that is clearly associated with another company's image or product line.