The goal of bttvgrab is to provide high-quality grabbing suitable for video recording. Currently, this is accomplished by trying hard not to leave out a single frame, and to catch temporary delays by buffering several frames. We have also synchronized sound and frame loss tracing.
Sound conversion is done as well.
Another use of bttvgrab is web-tv. Everything needed for that is included in the package. Audio is not currently supported, but is something we consider. This is like the primary goal but trading quality for space savings. I am interested in any experiences with non-bt848 based cards.