Vegas 4 CODEC Question

Mr_Plant wrote on 3/28/2003, 9:36 AM
Hi. Anyone out there know the answer to this regarding CODECs and re-encoding of footage.. here is my scenario..

1/. I capture some raw PAL DV footage into the computer using Vegas. This is saved as a DV AVI file of course.
2/. I trim the clip and alter the sound (EQ, compression etc).
3/. No filters or any other changes to the video other than as above mentioned trim
4/. I output the above edited file using SAVE AS AVI (PAL DV)

My question is - have I lost ANY video quality if you were to compare the original video DV file and the output from step 4?

Is Vegas just straight copying the input video to the output video as its smart enough to know that no filters etc have been applied? or does it all have to be re-encoded from scratch again?

What I am getting at here.. (and related to my last post!) is this would seem to me to be a workaround to using for example Cinemacraft Encoder (should I want to use this alternative encoder). I would want to feed it the best quality footage of course but need to apply simple edits to the raw footage as detailed above.

I have heard someone say feed Cinemacraft HUFFY files (huge uncompressed frames I take it) which is fair enough if there are lots of filters etc. but for my needs above - am I RIGHT in thinking I am losing NO quality with the type of edits I would be performing?

Lastly, say I was to superimpose some titles onto the start of the footage (at step 2 of above!), would it ony re-render the specific part with the titles on it?
I would obviously loose a tiny but of quality on this part due to the re-encoding I take it.. (in theory although you might not notice it in practice)??

I can't try any of this out (yet!) - just wanting confirmation my theories are correct..

I hope this makes sense - am writing in a bit of a rush here.

Thanks

Comments

DigVid wrote on 3/28/2003, 10:38 AM
1.) Vegas 4 (like Premiere 6.x) will only rerender areas that you add things too (like filters, Transitions, FX, titles,etc.) as long as you "don't" tell it to. Otherwise, the uneffected video will remain just a pristine as it was when you imported it.

2.) Vegas 4s Main Concept MPEG encoder seems to work almost as good as the CCE-Basic encoder that I just bought and better than the current vers of TMPEnc-Plus 2.510 that I am currently using (this is with torture video like trees, water, fire, titles, etc. - things that I edit.) however, it encodes this good with single pass VBR encoding. The CCE-Basic uses 2 pass VBR and at that type will take a bit longer to render.

3.) DV is a "Lossy" video format so you will always have some quality loss with rerendering. Sometimes it's unnoticable and sometimes it can look bad (depending on titles, backgrounds, etc, etc). So, the answer to that is kinda open to subjective analysis.

4.) No, It won't rerender just a small area of the video frame. If you add titles to your video the whole video frame will have to be rerendered. I've never heard of a reasonably priced NLE that would do that (it's a neat idea though)...


Grazie wrote on 3/28/2003, 10:43 AM
DV you say, "will only rerender areas that you add things too " . . . how can I confirm this? Or better, how do I tell V4 to ONLY render stuff I've altered?

I'm very interested in your reply.

Grazie
jetdv wrote on 3/28/2003, 10:55 AM
Or better, how do I tell V4 to ONLY render stuff I've altered?

You don't have to tell it to. It already does. Anything with NO effects added will not be rendered. Even if you do a full "Render As", the unaltered sections are simply COPIED and are NOT recompressed.

Do a Print To Tape and watch the sections that render. It will ONLY be the sections you have altered in some way.
Mr_Plant wrote on 3/28/2003, 11:13 AM
Hi DigVid

Thanks for your reply- it confirms mostly what I thaught..

4.) No, It won't rerender just a small area of the video frame. If you add titles to your video the whole video frame will have to be rerendered. I've never heard of a reasonably priced NLE that would do that (it's a neat idea though)...

I did mean the whole frame when I mentioned this but I agree you have came up with a neat idea there - wonder if its technically feasible though... ;-)

I have just spoke to a company in London, UK and vegas is coming into stock very very soon!! Can't wait to order. Uk price is £750 inc. (for DVD version) which does seem a little steep compared to US price..
SonyDennis wrote on 3/28/2003, 1:27 PM
Two ways to verify that it's not recompressing your media:

1) Tools > Selective Prerender doesn't create any prerenders.

2) The Video Preview stays black during rendering. Rendered frames appear here if it needs to do any rendering.

If these are both true, you are doing a direct bit copy of the compressed frames.

///d@