I'm perplexed - rendering times funky

kameronj wrote on 8/31/2003, 10:10 AM

Okay...I admit - I can't figure this one out. Any input would be very appreciated. Although I can get the project done - I'm just trying to wrap my brain around why this is happening.

I'm working on some footage from a wedding (my parents 20th anniversary re-vowing thingamajig, to be exact). Anyway....I captured and have been working with it in VV.

The first draft I completed (to put on DVD) took about 4 hours to render. Then, I go back to the VV file, make some modifications (chop out some video, put in a few transitions, blah blah blah) - render to put on DVD....14 hours render time.

Then, I make a little change to the ending....render....4 hours.

Then....I do the DVD thing - show my parents the first draft...make some minor changes....render to MPEG 2....14 hours.

With 2 hours left...I realize the file is going to be waaaayyyy tooo big - so I stop that render, chop out some more video - get the project down to 1 1/2 hour....render (mpeg 1)....20 hours.

See where I"m going with this?

4 hour render...then 14...then 4...then 14...then 20.

I don't mind the long render times....that's not the issue. I just don't understand why the times are so drastically different each time.

With the exception of the MPEG 2 render - I've always just done a default MPEG1 render.

Any thoughts?

Thanx

Comments

farss wrote on 8/31/2003, 10:32 AM

Maybe I'm stating the bleeding obvious here,
I have two bits of video to encode and I'm running two instances of VV so it can all happen while sleep.
One is 30 mins long but has been cropped
Second is 90 mins long, no cropping

second one is now at 18%, first is at 10%. It makes sense, first one has to remap all the pixels in each frame.

I'm only guessing here, were your shorter render times due to having prerenderd files available,maybe?

The other trap I've fallen into is inadvertantly setting a track composite level to 99%, very easy to do by mistake, you'd never see the difference in the result but it blows the render times out.

kameronj wrote on 8/31/2003, 11:21 AM

Good points.

I can easily seeing me making a change that I didn't notice (i.e. track composite level). But on this last pass (20 hours vs 14) I really didn't do too much of nothing different except chop off some footage and move the rest of the footage down to close up the gap.

On the prerender - of late, I really haven't used that feature...so I don't think that could be it. But, funny part is (although I didn't mention it earlier)...some of the footage I did render out to a different file at one point.

Okay...here is what I did.

Original file - two hours (one big ass MPEG). Then chopped that puppy up in VV. So now I have x parts:

1. Intro (prior to ceremony)
2. Ceremony
3. Reception
4. First dance
5. Ending montage (stills from video set to music with ending credit roll).

Out of sequence, I worked on the ending montage first. I did this because this montage (minus the credits) is the opening thumbnail in DVDA for the DVD (albeit shortened to only a minute for the DVD). So I rendered the credit roll over the montage (about 2 1/2 or three minutes). So that is one file.

Then....(after a few drafts) I shortened the Intro from 10 minutes to something like 3 minutes - and rendered that to it's own file.

I really didn't touch the ceremony or the reception at all - so that is still from the original big ass mpeg.

However, I did pull out the dance sequence (slow song first dance for the coupple and then....oh gawd....the Eletric Slide - why didn't they just play The Macarena!!). I rendered this to it's own file sine I reedited the audio laying the orignal tracks on top of the video shoot (to beef up the sound). It took a bit of fancy editing with the audio to keep it in synch...but I did it and never want to hear The Electric Slide ever again in my natural life!! My luck when I die I'll go to hell which will be a very small elevator playing The Electric Slide as Muzak while I'm making my decent to the bowels of hell at a snails pace down a never ending shaft!! I'll be stuck for all eternity listening to The Electric Slide!!

That would be hell!! But I digress.

So...even though I have most of the video chunked out - it's not really "prerendered". But even so - without making too many changes from the last render, my render time grew by 6 hours.

All the files are already mpeg...so I really can't grasp a change from 4 hours to 14.

I'm probably doing something - but I just don't know what.

Thanks again for any insight.

RexA wrote on 9/1/2003, 12:56 AM

I don't know the particulars, but it has been mentioned here before (I think by SoFo guys) that Vegas doesn't really do well editing from mpeg source. I suspect that could have a lot to do with it. After you make edits, I think re-renders are inevitible and it could get ugly depending on how things align or something.

Is there a good reason why you are starting with mpeg rather than avi? I'm no expert, but I think if I had a big mpeg to make multiple edits on, I would first convert it to avi and use that material as the base for all future edits.

farss wrote on 9/1/2003, 3:55 AM

I'd agree wih RexA,
Unlike AVI mpeg has a GOP (Group Of Pictures), basically a full frame of info and then a sequence of difference frames and then another full frame of data.

Now if you chop that up, even remove one frame from the middle, from what I can deduce VV goes right back to the beginning, converts it all back to full frames one at a time and then converts it back to the required GOP sequence. This is a very conservative approach.

From what I can work out it should be possible to create simply a new sequence around the cut. This may mean one or two GOPs with less difference frames but everything is supposed to cope with that.

However VV isn't a native mpeg editor. Good mpeg editors seem few and far between and not cheap, also some of them require the mpeg file to be all I frames, not exactly what I would consider an mpeg editor.

kameronj wrote on 9/1/2003, 8:59 AM

Great points.

Thanks for the input.

Main reason for not starting with an AVI was space (by the way). Until I get my new gazillion gig HD, I'm a little limited with storage/working drive space.

But thanks for the input - makes sense now.