I have quite a lot of video saved on my computer which I have to convert to avi so that my son can watch them on his t.v. I wanted to reduce the size of these files
instead of the file getting smaller they keep getting bigger even though I follow the instructions step by step.
Hello, and let me bring some light to your problem. I won't give you an actual answer though, but I hope it will help you find one.
What you must understand is, video files are tricky. For example, AVI is not a simple format, it's a container. Inside the AVI file there is 2 or more streams of data, video and audio (might be few of those), each of them compressed or not.
So, to say the file is AVI is to not much. There is many many choices in compression methods (codecs used) which will define what size is it, what quality of audio and video, what devices or software will be able to play it.
First thing to do, you must know which codecs your son's TV will support. For example, it might be able to work with AVI that uses DivX for video and MP# for audio, and in the same time it might not work with AVI that uses more advanced H.264 for video and, say, OGG/Vorbis for audio. More even, the codecs themselves have a lot of settings, and some of them will render your file to be unplayable on a hardware device, because they are just too complex and new and not supported.
You might study the manual for a TV (or whatever devices will be used by your son to play video on TV) for the list of file formats and codecs supported. Or, you can try and find the combination that works for this particular device and does not cause problems.
Some video converters have presets akin to "Home Theater" and so. It might be wise to try them first, they are more safe and might improve your chances on smooth playback on hardware. But you can't be 100% sure until you try, because there is a lot of models of hardware, and they have their issues and idiocinracies.
Second, as for huge size of the file you got. You must have chose wrong settings, and thus you either gor uncompressed video and/or audio in the file, or simply used ineffective codecs.
It would be a good idea to first study your source files, as to which codecs they use, and you never mentioned the file formats. Since most of the video file formats are actually containers, they can use different codecs for the data inside, to compress it. It might happen that they are alreadyuse the codecs that your son's hardware can work with, they just use wrong container. For example, they use MKV instead of AVI, but still use "acceptable" codecs within it.
Many software video players such as KMPlayer and LightAlloy can not only show you the video, but also provide information bout codec used for it, and such. There are also some utilities that simply show what file and with what content you're dealing with.
Third, as for software to use. I cannot really recommend anything simple, I'm not working with video on that level (I use more complex tools that probably won't be very useful to you). VirtualDub is a good tool, but it requires some familiarity with both it's settings and the general principles.
You might be better off with something more simple, that will not let you do a lot of tweaking, but due to this you will have less chances to make an error.
I would recommend to visit download.cnet.com — Home > Windows Software > Video Software > Video Converters section and try something from free software they list.
But you still must understand which codecs to choose, and which settings to use.
I would recommend to try a combination of DivX and MP3, with no additional audio or video streams (if there are any in your files), try it on one file and make sure it will be played on TV.
You might need to try a few settings until you find one that will be okay for the TV or whichever gear you will use.
Please, make sure that you understand the concept of bitrate, and the quality/size tradeoff when you're dealing with lossy compression (and you are dealing with it here). Otherwise, you will still end up with huge files.
Please, feel free to ask any questions, if needed, I will try to explain anything you have issues with in as much simple way I will be able.