A work colleague recently gave me a DVD with several AVI files. Each of the videos is crystal-clear, similar to the quality when playing the video back directly from the camcorder itself. Interestingly, each AVI file is only a few hundred megabytes in size. However, whenever I attempt to create an AVGI movie the picture quality is also degraded and the overall size of the file is dramatically increased. How can I download the video while also compressing the file size, without losing any picture quality?

You may recall that last week a reader asked why video files playback correctly on their computer, but will not play when taken to a different computer. This is due to the required video codec not being installed on the other computer, as the codec handles the decoding of the video footage for display on a computer. Without that codec, the computer does not have the “knowledge” (for lack of a better term!) about how that video should be decoded. In other words, it can’t understand the language in which that video has been encoded. Therefore, it cannot play the video back. This relates particularly to the question which you are asking. It is likely that your work colleague is using a different codec to encode their videos. This codec would have a higher compression ratio than the one which you are using, as it results in very high quality video output while keeping the file size relatively small.

At this point you may be thinking that you actually are both using the same video codec, as both files have the AVI file extension. However, the AVI file extension simply denotes the file type (i.e. an Audio Video Interleave file) which can contain audio and video content which has been compressed using a variety of different codecs. As you can tell, it is actually quite difficult to tell exactly which codec is being used in a particular file! There are utilities available which can check the file and show which codec is being used, but in many cases this will lead to more difficulties as often it is hard to find the codecs which you need to download since they are normally incorporated into other software packages. Therefore, the easiest way around this problem would be to ask your work colleague which software they are using to encode the video and then purchase (if the software is commercial) and install the package onto your computer, so that you can use that same software. In fact, this is really the only guidance I can provide, as without specific information on the software which your colleague is using and the software which you are currently using, I cannot tell you specifically which codecs you will need to use. Make sure that you also ask your work colleague to provide information on the settings which they are using in the video encoding software, as such settings are likely to affect the outputted video size and quality.