I am not good at typing chinese characters so I keep it in English.
I had download a movie in rmvb format. It works fine in my computer but when I try to convert it to DVD format. The software said it cannot open the file (not supported or damaged). I tried 3 different software alloksoft, rmconverter and winavi, it all report the same. I believe it is something wrong inside the rmvb file but I can play it without problems? Do I need a extra steps for convertion??
Thank for your help in advance.
kin

If you had trouble opening the rmvb file, it is most likely because you are missing the right codec.  Try downloading and installing K-Lite Codec pack from http://www.free-codecs.com/download/K_Lite_Codec_Pack.htm .

++EDIT++
Before you go on with my suggestion, have you tried another rmvb file and has the same problem?

Reinstall Windows.
I suggest a reinstall of Windows because it sounds like something is screwed up in your machine, too many hackwares and  different codecs can create major problems. Install WinXP if you can, Win98 and ME are not optimized for video editing/conversions.

If you don't have the OS on separate partition, you can try to do a *repair, which means instead a clean install, Windows will reinstall the system registry only, all the drivers will be gone but all the softwares and apps and other important personal files are left intact. All you need to do afterward is updating the drivers.  Infact I would recommend reinstalling all your applications.

When you're done, install K-Lite as Mickey advised. It is the only codec pack I had found no problems so far.
Also, try not to install * ALL the encoders you have found on the net. App like Winavi uses its own decoders, it may conflict with other softwares. MainConcept is another one that doesn't seems to get along with a few other apps.

Thanks agelessoldman!    

I wanna add this:

When I installed K-Lite Codec Pack, I only installed the following and rmvb > mpg conversion works fine:

DirectShow Audio Filters:

    * MP3
    * AC3
          o AC3 Filter 1.01a
    * Vorbis
    * AAC
          o 3ivx Pro
    * Music Pack
    * Monkey's Audio
    * WavPack
    * FLAC
    * Voxware MetaSound
    * AAC Encoder (3ivX Pro)

Is that what you guys installed too?  Or you just took the default?

I wouldn't be too concern of specifying which codecs to install when installing K-Lite. As long as the pack was installed after an clean OS. Just go ahead with the full version.

In the old days ( actually, not too long ago) when too many inexperienced, careless enthusiastic programmers built their codes without doing any extensive tests, and released them too soon, the codecs were so buggy, causing conflicts not only to other codecs but also to its own update versions.

Some would tried adding extra features to existing codecs since these are all open sources, without considering the extra features may create conflicts with others. Some softwares vendors would tried to do too much by trying to support as many formats as it can, thus resulting screwed ups after screwed ups for every newer version. Example---Winavi.

But lately, I'm seeing alot of maturing of open source codec developments, a few of these packs are quite stable. Including K-Lite and ffdshow. However there are still plenty of unstable codec packs to be avoided. These are solely my opinions.

The only time to be cautious is when updating a new version of a specific codec. Although its rare but sometimes it requires the older version to be removed before installing the new ones. Do not just search the net and download any codecs when Windows claimed you don't have it in your system,  do a search with an utility that can identify all the codecs you have, so you may try other solutions if the codec does exist. There are plenty of such utilities.
http://www.free-codecs.com/DirectShow_Filter_Manager_download.htm
http://www.analogx.com/contents/download/audio/dxman.htm
http://avicodec.duby.info/

Any time when you need a certain codec and were sure such codec isn't included in your codec-pack, it is always a good practice to image (backup) the present perfectly working registry before download and install the new codec. Because some codecs cannot be removed by just using the Add/Remove utility in the Control Panel, it'll remain in your system. So if after installing that certain codec and later found it causing problems, you can just go back to the original registry setting. System restore would work the same with a bit more hassle. (I never turn system restore on with any of my machines.)

Sorry if I sound like lecturing and drifted off topic..Just wanted to share my experience with more advanced hobbyists.

mickeyGoUp :
agelessoldman, thanks for sharing your valuable experience! I am sure a lot of pepole will be beneficial from it! :) At least I was!

I guess you are right.    And I thought I installed the codec pack on an ok image (started off with a fresh XP installation, plus a few basic applications), however, after I installed the full codec pack, when I played dvd (using WMP), the audio did not work anymore.  There was no sound.  Therefore uninstalled and reinstalled, and narrowed down to the above list that both rmvb-to-mpg conversion and dvd audio would still work.  I guess my principle is: install only what I need.   I try not to install anything that is not useful on my system, to avoid conflicts.  

Mickey, I had similar experience of what you went through with the audio, what I did was I decided to have directshow to decode most (if not all) of my A/V's. It worked out pretty well.

I have long suspected directshow would decode with better results, I started to use DirectShowSource instead of AVISource on my avisynth scripts more or less two years ago on all avi to mpeg conversions, picture qualities are visually better. Maybe because I had tweak the directshow codec properties on ffdshow, or maybe the colospace would had to do with the improvements...That I'm not too sure for I'm still in the elementry stage of learning what exactly differences among all those flavors of RGB and YUV colorspaces.

But all and all, I would highly recommend switching everything to directshow. Directshow can decode any video formats and most audio formats ( AFAIK). MP4`MKV`...I'd tried them all. Yes, and it can also decode all the old basic Video For Windows codecs like mpeg1 and such. So far the only codec I had problem with is the multi audio tracks and subtitle streams on MKV files. However that can be easily solved with other methods.

A bit off topic again, but I have to say this: I strongly suggest everyone whom are into videos to try to learn how to use avisynth scripts. It has its shortcomings like lack of preview functions on filters and have to learn all those commandline like syntaxes. But once you've tried it, it will bring your knowledge level up real fast. After awhile, you 'll start to realize what you had done before (encoding/conversions/making DVD's....) were so .....newbish (?)

Reason I sounded like I'm ranting here because I just finished converting the Devil..vcd-rmvb...It doesn't look too well...If the source vcd's are legit copies, not bootlegs, then the rmvb encoding job was just, badly done...I'm pretty sure the encoder just simply fed the mpeg to any one of those all-in-one type of softwares, without applying the proper filters and tweaks. Oh well, end of my rants. Thank you for reading

What you were talking about were fascinating!!  And to be honest, although you kept saying you are only at the elementary level, you are way beyond me already!  

Please bear with my naive questions, but what does avisynth script do?  I am interested in learning that.  Maybe we should start a new thread to talk about it, if you have time?  

I'm not being humble. I long realized the more you know, the less you actually knew.

Although I first learned about avisynth a few years ago, I was reluctant to try it . Just because I was doing ok with what I knew (I started playing with S/VCD since '99), why fix it if it ain't broke? Ofcourse, I was never good with commands, I was intimidated by it. But like alot of people, I started to grew picky with the qualities of my encodes with limited tools, that's when I braved myself to try out avisynth. ( I regretted for waited so long )

Avisynth is a frameserver with ability of applying various types of filters with lightning speed. Here's an old post I found which you can get a better understanding, the post was written in 2002, so alots been updated since: http://forum.videohelp.com/viewtopic.php?t=99389

It is extremely easy to start making your first basic script, which you can use it to frameserve almost all sorts of formats to a directshow enable player or to most encoders. (Only encoder I have problem frameserve the script to is Winavi, and this is the only "all-in-one"  encoder I have, so I wouldn't know how it fares with other all-in-ones).

Benefits of frameserving, as long the video file has no major problems, like too many corrupted frames or was badly encoded, the frameserver will decode any formats* and feed the frames of the video file one frame at a time. While quite a few encoders might struggle and choke with the video file due to a varieties of reasons.

While frameserving, different filters can be apply along simultaneously. Usually performs faster than build-in filters of most video encoders.

The benefits of frameserving with avisynth are enormous. Encoders job is to encode, while some encoders may have build-in filters, but they are often limited and extremely slow when certain filters were applied. And because avisynth is open source, there are so many hard core enthusiasts constantly adding new useful filters to support avisynth. I don't think any commercial softwares can ever catches up.

Premier and Vegas may have plenty of good filters to work with, but I think the learning curve would be alot tougher than avisynth. Besides, both softwares might choke on certain video files as well. They would probably work better with avisynth.

I'll try to find some time and start a thread to share what I'd learned. But so far it is very limited, I'm a slow learner. Hopefully some others will also share their knowledge of avisynth as well.

I just find out that my question was moved to here. Thanks for all the advice from mickeygoup and agelessoldman. You suggest I install the codec after a fresh install of Xp( current window system I am using) but I brought this system with bundled software. In other words, I don't have the original XP software for re-install. Where can I find a copy of install cd for Xp? and where I can find out what cd keys for my system? Did the register has it?
Sorry that I had so much question because I am just a beginner of beginner. I should go for the avisynth instead of directshowsource right? what was the step to do it? from rmvb to mpeg2 then to dvd. what about dual audio rmvb file. Can the software seperate it?
I download the avisynth but still not sure how to use it?. It said I need to create a script to run and the sample is not clear to me, is there any experience suggestion??