Compressed video gets bigger

[pickarooney]

Can anyone explain how this is possible: I take an mpeg (not sure if its mpeg1 or mpeg1, if anyone knows a program that can check that?) that's 500 odd MB, I compress it with avidemux2 with the xvid video and mp3 audio codecs, picking 220MB as the output file size. It compresses for about 4 hours and at the end I get a 1 Gb file, whose properties indicate xvid/mp3.

[hard candy]

"Other factors that affect file size
Some video characteristics can affect the size of a video file whether compression is applied or not, and regardless of
the codec you specify.
Factors that affect video compression
Bit Depth
The bit depth determines the number of colors that will be used to export the movie. Higher bit depths create larger
files. When you specify lower bit depths, you may be able to retain some control over color quality by specifying a
custom color palette. If the option is not available, you’ve chosen a codec that doesn’t support custom palettes or 8-
bit color.
Frame size
For best picture quality, the frame size of the project should match the frame size of the final video file. Where file
size or data rate are more important than picture quality, such as for Internet delivery, reducing the frame size may
help compression by reducing the initial amount of data to compress.
Frame rate
For best motion quality, the frame rate of the project should match the frame rate of the final video file. Where file
size or data rate are more important than the quality of motion, such as for Internet delivery, specifying a lower frame
rate may help compression by reducing the amount of data to compress."
I would look into uncompressing the file and then compressing it with the new codecs. It may be it is trying to switch some characteristic of the file, frame rate, frame size, bit rate, etc, and that is causing the increase.