This area lets you specify the height and width of your video. By default, it'll be set to the same resolution as the smallest video in your project. The dimensions combo box holds a variety of standard settings, and you can check the "Set Custom Dimensions" box to set whatever dimensions you want.
A few things to remember when setting custom dimensions: height and width must both be even multiples of four, or DirectShow will refuse to render. If the dimensions you choose are too large, DirectShow may not have enough memory to render the video. And if you choose dimensions with a different aspect ratio than your original videos, the resulting video may look stretched or squashed.
This area lets you specify your video's frame rate (how many frames per second the video will contain). By default, it'll be set to the highest frame rate found among the video clips in your project. (To learn what a video's native frame rate is, right-click on the video clip and select the "Properties" option from the menu that pops up.) The Frame Rate combo box contains a variety of standard frame rates, but if it's missing the one you want, you can check the "Set a custom frame rate" box to type in a specific frame rate.
Should I change the default frame rate?
Probably not. Increasing the frame rate to one higher than the frame rates found in any of your project's video clips will typically increase the size of the video file without increasing quality, while decreasing the frame rate will usually lower the quality. Even if your primary concern is video size, changing the frame rate is not necessarily useful; depending on the encoding method you choose, lowering the frame rate can actually increase file size. If you're trying to alter the frame rate to produce smaller file sizes, you'll need to experiment to find the best setting.
Video Bit Rate:
This setting specifies approximately how much bandwidth your video will require, in kilobits per second. It's one of the primary factors affecting compression. Higher bit rates mean larger files and higher quality, while lower bit rates will result in smaller, lower quality video files. The right bit rate to use will depend on the dimensions and frame rate of your video; a bit rate that produces a high quality 720 x 480 video may result in a grainy, pixilated video if you use it for a 1440 x 1080 video. You may need to experiment to find the results you like best for different types of video.
Video Encoding Method: Microsoft provides a handful of encoding methods for WMV creation. Which one to use will depend on your priorities - quality or file size - and on your video content. In practice, an encoding method that produces the best results for one video may not produce the best results for another, so you'll have to experiment if you want the absolute best results for each project.
Constant Bit Rate (one pass): This method was designed to handle live streaming video, and will usually produce the lowest quality results when rendering to a file. Because it's a one-pass method, though, it takes half as long to render out to file as the two-pass methods, so it might be the choice for you if the world's ending in a few minutes and you really want to be able to watch this video before you go.
Constant Bit Rate (two pass): This method will usually produce good quality video if you've set a sufficiently high bit rate. Because it's a two-pass method, it'll take twice as long to create the video as one-pass methods will. Since the bit rate will be consistent for the entire video, it should work well for videos that you intend to stream over a network or the internet.
Variable Bit Rate with Quality Setting: Using this encoding method with the quality slider at its highest setting usually results in higher quality videos than any of the other encoding methods. However, the resulting video files tend to be about three times larger, as well. Use this method if quality is absolutely the highest priority. This is a one-pass encoding method, which means it will take roughly half as long to create the video as with two-pass methods. (The number of passes refers only to the creation of the video, and doesn't affect the speed of video playback.)
Variable Bit Rate with Bit Rate Ceiling: This two-pass method uses a variable bit rate, which means that it's likely (but not guaranteed) to produce smaller file sizes than the constant-bit-rate methods. With variable bit rate encoding, the bit rate you choose will be the average bit rate, but actual bit rate during playback may vary depending on how complex the video is. (Sections of video with lots of motion will probably have a higher bit rate, and sections with little motion will have lower rates.) This method has a max rate ceiling, which means that it'll keep the highest bit rates from being much higher than the average bit rate. Consequently, this method will work better for streaming than the Unconstrained Variable Bit Rate method, but may not produce video of quite as high a quality.
Variable Bit Rate (Unconstrained): This method is similar to the VBR with Bit Rate Ceiling method, just above, but lacks the bit rate ceiling. This means that while your specified bit rate will be the average bit rate for the video, the bit rate could reach infinitely high (or at least really, really high) levels during short sections of the video. This could cause playback to get choppy during these sections if you're streaming the video, but can also result in higher quality for these sections, making it a better choice for video that you're planning to playback from a hard drive.
Audio Quality: This section lets you choose the quality of the audio that accompanies your video. It will list all the available WMA audio-quality options installed on your computer that are compatible with WMV video. Audio almost always uses much less disk space than video does, so choosing a high audio quality setting will rarely have much relative effect on the overall size of your video. 128 kbps will usually produce good results for music audio quality.