Tough question; what one person calls low-motion, medium-motion, and high-motion video and how the codec interprets this motion might be quite different. There probably isn't one "magic bullet" codec for all types of video at multiple data rates. But here are some guidelines:

MPEG-4 works best across a range of video motion from low-motion, low-bit-rate video to high-motion, intranet-bit-rate video. It is clearly the codec of choice for working with a variety of video motion types; however, for video that contains a constant and definable amount of motion, other choices might be considered. MPEG-4 is designed such that the images are crisper and moereblocky appearing than with VDO, for example. This works excellent for low-motion type video. However, when the motion rate increases, this blockiness may be less visually appealing.

H.263 is a low-bit-rate video codec optimized for low-motion, talking head-type video. For this type of video, the image and motion quality may be the best of the three video codecs mentioned here. However, if the video contains a sudden combination of low and high motion video scenes, this is not the codec of choice. While the low-motion scenes might be high quality, the higher-motion video quickly becomes unacceptably smeared or pixelated.

VDO, on the other hand, is designed to compress the video in such a way that the images appear smoother and softer. This gives less definition for low-motion video such as talking heads. However, with high-motion this smoothness often works better than the crisp, blocky appearance associated with MPEG-4.

One other characteristic of video besides motion and scene changes is the visual texture; for example, a video with a snow skier on a slope, with a heavy background of trees and a partly cloudy sky, has a large amount of texture. The smoothness of the snow and the details of the trees between the snow and sky make a complex, contrasting texture which various codecs handle differently. MPEG-4 is quite good with this type of complex texture video, while VDO makes the video look very soft, losing much of the detail. Another issue is the final data rate; MPEG-4 is optimized for high-texture scenes while VDO is optimized for low-texture scenes. This results in a lower final data rate for MPEG-4 compressed video than with VDO.

In summary, for low to high-motion video or video with high-texture scenes, MPEG-4 is an excellent starting point; VDO is certainly an option, however. If the video exhibits medium to high-motion or is primarily low texture scenes, VDO is probably a better starting point than MPEG-4. For low-motion, talking head-type video, H.263 is an excellent choice. The one point to keep in mind is how consistent is the motion factor in your videos; if it is variable, MPEG-4 is probably your best choice. However, your preference might be different, so I suggest that you do some tests with different types of video you commonly work with and determine what is visually most appealing to you.

A comprehensive study on various computers and CPU utilization is available which provides many details related to encoding machine selection, different types of video encoded, codec selection and configuration, and so on. See CPU Utilization Study.

That's easy -- you don't! VidtoASF converts the .avi or .mov (QuickTime) file to an .asf file with a few options such as changing the audio file used, setting the amount of buffering time at the beginning of the file, and so on. But the data rate is determined at the video compression stage when the .avi or .mov file is being made. If you have to change the data rate of the video file, you must return to the videoediting program that produced the video clip and recompress the file at another target data rate.

In on-demand created video content, the ability to scan forward and backward through the video clip by moving the slider on the Media player is determined by whether enough key frames are present and which codec is used to compress the video. VDO, Duck, Cinepak, Indeo 3.2, and Indeo 4.1 all allow scanning if you use the codec's default key-frame interval. On the other hand, MPEG-4 doesn't allow you to seek when you use the default key-frame setting. By decreasing the key frame value you can have the video to seek.

There is one way, however, of allowing a video to be "seekable" without altering the key-frame values. When the .avi or .mov file is converted to an .asf file using VidtoASF, set the seekable flag to on. For example:

Content produced with NetShow Real-Time Encoder as part of NetShow v2.0 normally doesn't create seekable .asf files. ASFChop creates an index on .asf files longer than 10 seconds so that you can seek (similar to fast-forwarding) through the file. To do this, specificy the -in and -out commands without any time, and be sure to give the output .asf file a different name than the input .asf file.

Content produced with NetShow Encoder as part of NetShow v3.0 integrates the ASFChop indexing functionality. Indexing of .asf files can be done automatically from within NetShow Encoder. Since this is potentially a CPU-intensive process, this option is in the Local File options property page or in the Custom Configuration wizard. The default setting is on and the procedure is started upon completion of encoding the .asf file.

Yes. A dialup line with a good connection should be adequate, though using 33.6-Kbps modems at each end would be better and using ISDN would be optimal. Keep in mind, however, that just because you have a modem capable of providing a 28.8-Kbps connection, this doesn’t mean that you will always get all the potential bandwidth. Due to network traffic, network "noise," or other factors, it is not uncommon to see no more than 24-26 Kbps connections on a 28.8-Kbps dial-up connection.

This is one of the main reasons that the suggested total bandwidth for ASF content targeted for a 28.8-Kbps connection should be no more than 23-24 Kbps.

Premiere 4.2 currently does not allow you to make a movie using the MPEG Layer-3 or Vivo audio codec. The solution is to select another audio codec, make the movie, and then use one of three approaches:

MPEG-4 requires the frame size to be evenly divisible by 16. For example, a frame size of 160 x 120 gives this error, while a frame size of 160 x 112 or 160 x 128 build without incident. The solution for this problem is easy; change your target frame size to be evenly divisible by 16.

Third-party applications may handle how they display codecs differently. For example, one video editing application might display every codec installed on your machine whether it can actually use it or not. Another video editing application may display codecs more intelligently; whether the codec is displayed is dependent on whether the codec can actually be used on your system and whether all your output settings are appropriate for the codec.

An example of how two applications handle the display of codecs differently is described below.

A Windows 95 system has the following video codecs installed as displayed in the Advanced dialog box of the Multimedia Control Panel applet.

Adobe Premiere recognizes all codecs except #5, Microsoft H.263 video codec. Regardless of the video settings, this codec does not appear in the codec selection list. In Corel Lumiere, however, if a correct frame size is used, the codec is displayed. For example, if you use a frame size of 160 x 120, the codec does not appear, while if you use 160 x 112, the codec does appear.