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I am having difficulty editing motion screen cature from CamStudio using Video Studio 11. I am making an instuctional video to teach how to use a software program that is coupled to an external audio processing device so there is need to mix movie files and software screen capture. The files from CamStudio are 15 frames/ sec and a simple 640x480 184kbps 16bit MS-CRAM video compression.
I can import them onto the time line ok along with .mov files from the video camera and edit them etc. When I view the individual scenes via the clip preview on the time line the screen captures are fine. The problem arrives when I view the whole project via the preview screen that screen capture becomes blurred, and when I burn a DVD the screen capture flickers as well as being blurred. The video camera sections seem fine on the DVD. I would appreciate some comments from those with experience in this area please.

It seems from your post you are mixing different types of media on the timeline. CamStudio and the .mov files.
Right click on the .mov files to see what frame rate they are recorded at.
It sounds like they are different to the 15fps of the CamStudio files so when you play an individual file VS is fine but when you play the project VS has a brain fade trying to work out what frame rate to go with.

The .mov file properties are Mpeg 2 upper field first. 24bit 720x576, 4x3 25 frames/sec. I must add that I tried to just mix the CamStudio videos .avi on a time line and even without the .mov files the end result was the same.

Well that pretty well explains the problem.
The .mov files require an MPEG2 codec rated at 25 frames per second with a resolution of 720x576 which is stock standard PAL.
The CamStudio files are 15 fps at 640x480 and use another codec.

If you have your project properties set at, say, the PAL DVD standard then VS has to "invent" 10 frames per second to get the CamStudio files up to scratch as well as "inventing" 80x96 extra lines of resolution.
If your project properties are set for the CamStudio specifications then VS has to get rid of 10 frams per second of the .mov files as well as chop 80x 96 lines off the MPEG2s.

The software is simply not designed to deal with this type of conversion especially "on the fly" which is what it is attempting to do when you preview.
Your best bet is to convert to one standard using another specialist software for the purpose.
Many users have reported good results with "SUPER" a free conversion software program.

As an added note you may also want to standardize the bitrates of the two types of media to minimise quality loss.

Thanks for your help. I will digest this information and try to convert to a fixed standard. Again, much apprecated.