Error when saving from VirtualDub as AVI with compression

[Thread7]

I cannot save any of my movies in Virtual Dub with compression. This only thing that works is "Uncompressed." Otherwise I get the error -
"Cannot initialize smart rendering: The selected video codec is able to compress the source video, but cannot match the same compressed format."

If I choose "Video" / "Compression" from the menu I have several things to choose from: Uncompressed, Cinepak, ffdshow, XVid, Microsoft RLE, among others. But I get that same error when trying to save as AVI no matter which I choose - except for Uncompressed.

[AlanHK]

For "smart" rendering it has to use the same codec as the original file for the parts it encodes. Evidently you haven't installed that encoder.

VDub should tell you the codec, or many media analysers can .

[Thread7]

Oh yes, when I uncheck "Smart Rendering" it works fine. I guess now I want to know why I should or shouldn't try to use Smart rendering.

[jagabo]

As was pointed out you need to use the same codec as the existing video if you want to use Smart Rendering. File -> File Information will tell you what codec is used in the currently opened video file. Note that this won't work with some sources -- an MPG file, for example.

[AlanHK]

Oh yes, when I uncheck "Smart Rendering" it works fine. I guess now I want to know why I should or shouldn't try to use Smart rendering.

Smart rendering is much faster, and also does not degrade the quality as reencoding inevitably does.

[jagabo]

You use Smart Rendering when you want to trim out small pieces of a video without reencoding most of it. Only cut GOPs are reencoded. This is why the compression codec needs to be the same as the source. You can only use one codec through the entire video.