Convergence: Exporting for Multimedia and the Internet
| Exporting a movie as a digital (computer) file for multimedia or the Internet is easy. The hardest part is understanding all the different types of variables that come into play when you're creating digital files and trying to decide which type of file is the best format for your needs. In general, there are two main areas to be concerned with: the format type and the data rate. The format type determines whether your end users can see the clip (do they have the right drivers or player to open and play the medium?). The other aspect, data rate, needs to be considered more for Internet use than CD-ROM development. Data rate is the amount of information that is passed per second. If your connection speed is too slow, your video will either be choppy (skipping frames) or extremely slow-moving (more like a slide show than a video) or will take extremely long to download. One area where Premiere has really improved its capabilities is in its exporting options. Premiere utilizes the proper plug-in support engines to output your media in the desired format. You can choose between the Save for Web, Advanced Windows Media, and Advanced RealMedia export options, among others. To export a clip, a portion of your edited sequence, or the entire timeline, do the following:
The following are the types of files you can export in Premiere:
Now comes the fun part trying to figure out what each control is and how its settings affect the final output quality of your medium. Depending on which file type you choose to export your movie, various options and controls are available. These controls determine your movie's file type, size, and quality (among other things). CodecsThe greatest challenge for any DV editing system is to reproduce the highest-quality video signal. The problem is that it takes high-end computer systems to capture and play back high-quality video. Therefore, many companies have introduced various forms of compression technologies that allow standard computers to play back video files. Compression/decompression applications are called codecs. Codecs compress large files into the smallest possible components while trying to preserve the best possible quality. When exporting your movie from Premiere for multimedia use, you use one of these compression formats to compress your original DV file to reduce its size and optimize it for playback on your computer. Then, using the same technology, you play the video clip back on your computer using the decompression portion of the application. There are several different types of codecs:
Creating the best-quality movie is important. My advice is to export your movie with various compression settings applied to it. Keep track of which settings you adjusted so that you can compare the results and find the best combination of settings for your needs. I also recommend becoming familiar with Discreet's Cleaner 5, shown in Figure 10.12. It is by far the best compression application on the market. You can choose to repurpose your movie into just about any type of digital media format. This easy-to-use program is a must if you want flexibility and control to produce the best-quality digital media files. Check out Cleaner at www.discreet.com. Figure 10.12. Discreet's Cleaner 5 Settings and Control window.
note A stripped-down or EZ version of Cleaner comes with Premiere. tip Having complete control over your movie's settings, as in Cleaner 5, allows for ideal file size, especially in today's push for video over the Internet. Cleaner 5 even writes out HTML embed tags for non-web programmers. Data RateAfter you choose a codec, the next most important aspect that determines the file's quality and playback capability is the data rate. Every computer is configured slightly differently, and distributing digital media can be a challenge. Because some of your end users will not have the latest and greatest system, optimizing your movie for playback is an important consideration. The data rate determines how much information the computer system can process for that file. If the data rate is set higher than the computer's playback capability, the video file either plays slower than it was set to play, drops frames randomly, or freezes up. Determine how you want your end users to optimally view your movie. If they will be playing the movie from their hard drive, you can set a high data rate. If they will be viewing the clip from a mid-level bandwidth channel, such as a CD-ROM or an intranet, drop to a range between 100 and 300 KBps. If the end user is viewing the media files via a dial-up modem, you might be forced to consider 28.8 to 56 KBps for transfer rates. note The lower the data rate, the lower the quality of your image. Key FramesSome codecs let you set keyframes. Keyframes act as a starting point for the compression processes taking place. This type of compression is called temporal compression. Temporal compression basically works by compressing the changes frame by frame from a given point. Therefore, if a keyframe is set every fourth frame, the next three frames use the previous keyframe to compare patterns or repetition of pixels. note When exporting your movie, set keyframes in the Keyframe and Rendering Options window under the Export Movie Settings menu choice (see Figure 10.13). Figure 10.13. The Keyframe and Rendering Options window.
Setting a keyframe every frame would allow for higher-quality playback, but at the cost of increasing the overall file size. If you have a pretty static scene, with very little movement, you can leave a greater number of frames between keyframes. For quick movement in clips, set a lower interval between keyframes. |
