You might read around
www.dvdtalk.com. Here are two big questions answered:
Q: What's the difference between software and hardware decoders?
A:With a hardware decoder, the audio/video stream is decoded on a seperate add-on board in your PC. These add-on boards have one or more chips on them that are like mini-CPUs designed specifically for decoding DVD streams. A software decoder relies heavily on the PC's CPU to get the stream decoded into audio and video which the sound card and video card can deal with. There is a thing call Hardware Motion Compensation that is included on some video cards to lower the amount of CPU that is required.
Q: Does my video card offer hardware DVD decoding?
A:I have yet to see a video card that offers full DVD decoding. Some video cards have Hardware Motion Compensation which takes a little bit of the load away from the CPU for the video decoding. Many of the ATI cards have motion compensation as well as the nVidia GeForce.
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As most home users don't have hardware decoder cards, your DVDs are handled mostly by the CPU. And
IF you have the motion compensation thing, that helps a little.
But chances are good your codecs are somehow bad or corrupt for those other formats.
Download the program "VideoInspector" from
http://www.kcsoftwares.com/index.php?download
It will give you interresting facts about the video files themselves and what they are and what codecs they use and whether you have them etc... It can list all the codecs you have in your system. Might be a good read.
Otherwise, you could try downloading a codec pack like the K-Lite Codec Pack. Browse around
http://www.free-codecs.com/Codec_Packs.htm and see all the codec packs there. I almost always load the K-Lite pack, including being able to read Real Player files and Quicktime without having to install those apps. Very handy. Although I think the one including that is called the K-Lite Codec
Mega pack. It's harder to find.
Good luck!