so there is no quality degradition converting mpeg2 to DV and back to Mpeg2 (eventually dvd) again?

all i can say is that never render mpg to mpg again, but also you are correct in saying what you just said except the dv to mpg part, loss of frames and unnessecary pixels

so there is no quality degradition converting mpeg2 to DV and back to Mpeg2 (eventually dvd) again?

That is NOT what I said. If all you need to do is cut out certain segments, yes you can use Womble's products and they will cut the MPEG-2 files without re-encoding. In that case, there is absolutely no degradation.

Sony's products could do this as well, but so far they have chosen not to include the technology to do this. Therefore, once you put MPEG-2 files on the Vegas timeline, no matter what you do (even just a cuts-only edit), the files will be re-encoded, and this will result in a loss of quality.

Given that this is the case, and especially if you are going to do something OTHER than cuts-only (like creating transitions, adding text, doing compositing, etc.) which will, by definition, require new video to be created, you might as well FIRST render the whole thing to AVI. This won't take long and will not result in any noticeable additional degradation beyond what you get when you do the MPEG-2 encode at the end of your project. However, the benefit you get from doing the intermediate encode to AVI and then using the resulting AVI file on the Vegas timeline is that your editing will be many, many times faster and easier. Vegas doesn't do any fancy buffering of MPEG-2 files, and therefore editing them on the timeline is very sluggish. This gets old very quickly if you have a long project.

Yes, there will be a quality degradation going from MPEG2 > DV > MPEG2, that's just unavoidable. If you're working in NTSC, then the colorspace conversion from MPEG2's 4:2:0 colorspace to DV's 4:1:1 back to 4:2:0 is going to present some chroma resolution problems.

Obviously, if your original MPEG2 file was encoded with a good encoder at a high bitrate, then the quality hit will probably be minimal. If the original MPEG2 file looks marginal to begin with, then the quality hit after editing and re-encoding may end up being wholly unacceptable.

No matter how you do it, MPEG2 > DV > MPEG2 just isn't an optimal situation. But sometimes we have to do what we have to do...

John

thanks for the replies ..so i'm basically stuck with one of 2 options

high quality MPEG2 converted to DV dropped directly into Vegas applying filters > MPEG2

or

high quality MPEG2 dropped directly into Vegas applying filters > MPEG2

so now (sorry I am still learning)

1) will there be any difference in quality using either above option?
2) will vegas render faster with filters applied to a DV vs an Mpeg2

"1) will there be any difference in quality using either above option?

Considering the 4:2:0 to 4:1:1 to 4:2:0 colorspace conversion going from MPEG2 > DV > MPEG2, from a quality standpoint, dropping the MPEG2 file into the timeline without the intermediate DV conversion would probably work best.

"2) will vegas render faster with filters applied to a DV vs an Mpeg2

Probably not. Even if it is slower, you will have saved the time of not doing the DV conversion in the first place.

John