Decoding codecs

Digital video contains a lot of data. If you were to copy uncompressed digital video onto your hard disk, it would consume 20 MB (megabytes) for every second of video. Simple arithmetic tells us that one minute of uncompressed video would use over 1GB. Even with a 60GB hard drive, you would have room for only about 50 minutes of uncompressed video, assuming that big drive was empty to begin with. Dire though this may seem, storage isn’t even the biggest problem with uncompressed video. Typical hard drive busses and other components in your computer simply can’t handle a transfer rate of 20MB per second, meaning that some video frames will be dropped from the video.
To deal with the massive bandwidth requirements of video, digital video is compressed using compression schemes called codecs (compressor/decompressor). The DV codec, which is used by most digital camcorders, compresses video down to 3.6MB per second. This data rate is far more manageable than uncompressed video, and most modern computer hardware can handle it without trouble. When you capture DV video from a camcorder using a FireWire interface, a minute of video consumes just over 200MB of hard disk space. Again, most modern computers can manage that. Why do codecs matter to you? When you choose a file format for exporting your movie, you’re also usually choosing a codec to compress your movie (whether you realize it or not). Usually your export software automatically chooses a codec for you, but as you’ve seen in this chapter, you can also usually choose a specific codec if you wish. Some codecs compress video more than others. Generally speaking, the more video is compressed, the more quality you lose. In most cases I recommend you use the default codec chosen by Studio (or whatever program you are using) when you select an export format.

Choosing AVI Settings in Pinnacle Studio

The AVI format was developed several eons ago by Microsoft as the file format of Video for Windows video files. AVI files can use one of several codecs to compress video. Codecs control exactly how the audio and video is compressed. As you can see in Figure, Studio’s Setup Options dialog box makes it pretty easy to choose a codec or modify other settings.
The video settings include

• Include Video in AVI File: I’m guessing you’ll want to leave this option checked for 99.9975% of all your projects. If you uncheck this option, only audio will be included in the file.
• List All Codecs: I recommend you leave this option unchecked. Many multimedia programs install codecs on your computer, and if you check the “List all codecs” option, each and every codec installed on your PC will appear in the list, even ones that aren’t compatible with Studio.
• Options: Some codecs have further options you can adjust. I generally recommend that you don’t mess with these options.
• Compression: This menu allows you to choose a codec. Many multimedia programs install codecs on your computer, so the list of codecs may vary depending on what is installed on your computer. The Cinepak codec (which comes with Studio) is pretty good for all around use, and is particularly recommended for movies that will be recorded onto a CD.
• Width and Height: These indicate the size of your video image in pixels. Full-size DV-format video is 720 by 480 pixels. Reducing the size of the picture can greatly reduce the file size, but make sure you keep the ratio between the height and width the same, or your video image may look distorted.
• Frames/Second: This controls the frame rate of the video file. Full-quality DV-format video uses a frame rate of 29.97 frames per second (fps). Reducing the frame rate decreases playback quality, but it also greatly reduces file size.
• Quality or Data Rate: This slider control isn’t available with all codecs, but when it is available, it allows you to adjust the quality up or down to control file size. A smaller data rate greatly reduces file size.

Exporting Your Movie to an AVI or MPEG with Pinnacle Studio

If you’re using Apple iMovie, QuickTime is the only file format available for export. If you’re using Pinnacle Studio, you have more options. To export your movie to an AVI or MPEG file:

1. In Studio, choose View➪Make Movie. The Make Movie screen appears.
2. Click either AVI or MPEG on the left side of the Make Movie window. Choose the format to which you want to export. Generally speaking, AVI (Audio Video Interleave) files are a little bigger than MPEG (Moving Picture Experts Group) files. Anyone with a semi-modern Windows PC should be able to view either format. Another benefit of choosing MPEG is that Macs can usually open them, whereas AVI files are usually not Mac-compatible.
3. Click the Settings button. The Pinnacle Studio Setup Options dialog box appears, as shown in Figure. If you chose AVI in Step 2, the Make AVI File tab will be in front. If you chose MPEG in Step 2, the Make MPEG File tab will be in front.
4. Adjust settings and click OK. I’ll describe the various AVI and MPEG export settings in the following two sections.
5. Review the estimated file size above the Settings button in the Make Movie window. The estimated file size is just that — an estimate. It’s usually pretty close to what the final file size will be, but seldom exact. If the file seems too big, adjust settings so that the video picture is smaller or the audio quality is lower.
6. Click Create AVI File or Create MPEG file to create your movie.
7. In the dialog box that appears, choose a folder in which to save your movie, and give it a filename.
8. Click OK.

The export process will probably take a few seconds or even minutes, depending on the length of your movie and the number of effects. One reason you might want to export a movie as an AVI or MPEG file is if you plan to edit it using other software. For example, if I want to export a movie for the Web in Windows Media Video (WMV) format, I prefer to use the export feature in Windows Movie Maker. When I’m done editing in Studio, I export the movie in AVI format, which can be easily imported into Movie Maker. After the AVI file is imported into Windows Movie Maker, I use that program to export a WMV file.
AVI is a good format to use if you want to export video for many Windowsbased video-editing programs, including Windows Movie Maker or Adobe Premiere for Windows, but you may find that some editing programs prefer MPEG. Pinnacle’s Hollywood FX Pro, for example, works better with MPEGformat video. And of course, if you plan to use the exported file on a Mac, you’ll find that the MPEG format will be much more compatible with Mac multimedia software.
If you aren’t sure whether you have a specific need for one format or the other, it probably doesn’t matter very much which one you choose. AVI files are usually a little bigger than MPEG files, but as I said earlier, if you’re concerned about file sizes — say, for example, you plan to share the movie on the Internet — you really ought to be exporting the movie in a Web-friendly format like RealVideo or Windows Media.