Windows Movie Maker can be Ok. I actually used it for a year when I was first starting out in the Video Industry.
The main problem in Video Quality is usually the Filming itself. For good video you need proper lighting, camera techniques, iris, focus etc.
Also, a higher speed Processor Computer, and more RAM also can help the look of it slightly, as well as improve the time it takes to render and capture files.
If you are using a USB Cable to transfer your video, or a means other than Firewire, that could be a big problem. Below I am listing the steps to using a firewire I posted on another question.
If you would like some tips on better filming, let me know by email.
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TRANSFER VIA FIREWIRE PROCESS
-For this process you will need a Firewire Cable (sometimes referred to as an IE 1394). This will be avaliable at most Electronics Store. For a laptop you will generally need a 4-pin (Laptop End) to 4-pin (Camera End) connector. For a Desktop it is generally a 6-pin (Desktop End) to 4-pin (Camera End).
-Once you have your camera hooked up, open a Video Editing Program on your computer. Generally Windows will come with Movie Maker (located under accesroies), or on a Mac you have IMovie.
-In either of these programs, depending on your Operating System, open the capture tool. If you have properly connected your camera, and have it turned on, in Playback Mode (VCR Mode), you should see it now on the computer.
***NOTE: It is usually best to turn plug in the camera, turn it on and put it in Playback mode before starting the capture tool in the program.
-Once you see it on the screen, you should have a button that either says record, or looks like the record button. Press this, and the camera should start playing and recording to your comptuer. If the camera does not automatically start playing, press play on it.
-Once you are finished bringing in files, hit stop on your PC. You now have these files on there, most likely in an AVI format (The Highest Quality).
-You can then edit and manipulate it however you want, and export it as a movie. To put longer movies on the internet or DVD, you will probably have to downsize it to MPEG-1 or MPEG-2. This is another problem for another day.
Contact me if you need help on anything. Best of Luck
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