I guess we need more details.

When you say it shrinks the file, what file? Are you looking at the size of the overall data that gets burned to the DVD or are you looking at the VOB file and it is smaller?

What kind of source file are you using, one with the audio included or is it separate?

Without knowing exactly what you are asking, one possible explanation is your source file may have the audio included, when DVDA rerenders, it removes the audio and creates a separate ac3 audio file, which is smaller then the original pcm file, and makes the mpg file smaller because it no longer has audio data in it. If you are talking about the overall size of the DVD shrinking, then that would be because the ac3 files are smaller then the pcm files, allowing you to fit more on a DVD then if it did not make that change.

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