Using previously rendered avi files

vegasnewbie wrote on 1/25/2004, 8:01 PM

I have rendered with Vegas 4 a small .avi file and I now want to add this .avi file into a larger project. I am interested to know whether there is any loss in video quality when you add into a project an avi file that has already been rendered. In other words, would I have been better to have done the editing of this piece of film in the larger project direct from the original avi captured file from the camera?

When you are doing a large project, it could be easier to render several different .avi files and then put them all together later in a new final combined project. Is this going to produce video quality that is good as rendering the whole large project only once from the original captured avi files?

Thanks for your comments, Fred

Comments

jetdv wrote on 1/25/2004, 8:06 PM

There will be no loss of quality when adding a rendered AVI file to another project. All non-modified clips will be simply COPIED when rendering. Recompression only happens on modified clips.

Chienworks wrote on 1/25/2004, 8:09 PM

If you've rendered to DV .avi using the DV codec included in Vegas, and then you drop this file into a new project without applying any effects, overlays, titles, filters, etc, then there will be absolutely no loss in quality. This section of the video will simply be copied bit for bit to the new file when rendered.

Even if you do add or change something when rendering this section in a new project, the amount of loss is incredibly minimal. SONY's DV codec holds up to a hundred or more generations of re-renders with almost no loss. See http://www.vegasusers.com/testbench/files/generations/ for demonstrations of how well it holds up over 99 generations.

vegasnewbie wrote on 1/25/2004, 8:22 PM

Thanks very much for these very prompt replies, I have never had an internet problem answered so quicky, two replies with one minute of posting!

I think there would be several advantages for a newbie in breaking down a large project into several, say, 5 minute sections, rendering each of these, and then combining them all later into one large project. This give you an early chance to see if each section has rendered properly and goes OK in DVD Architect. I would do all the transitions only in the final combined project. Does anyone else follow this approach, or am I being too conservative?

Regards, Fred

JL wrote on 1/25/2004, 8:36 PM

I routinely use this editing strategy. Breaking a complex project into smaller segments allows me to be editing one segment while another is rendering in the background. I hate to wait, and being able to run multiple instances of Vegas keeps my workflow going. Not to mention the final render of the overall project will go very fast since there is very little processing left to do at this final stage.

JL

GaryKleiner wrote on 1/25/2004, 8:38 PM

>. Does anyone else follow this approach, or am I being too conservative?<

You are being too conservative. Not only are you making extra work for yourself, but when you separate the rendered versions from the original media, you make it much harder to make any revisions later.

Gary

Apollo25 wrote on 1/25/2004, 9:12 PM

I use previously rendered avi clips on a regular basis. No loss of quality is experienced when using a rendered clip in a new project. I usually build my larger projects in segments. My opening sequences, closing sequence, credits as well as portions of the body my project are created in smaller sub-projects. These sub-projects, once rendered, become the major elements of my final project VEG. It also allows you to fly through your final project render.

Note: When possible you should always edit using footage in the native DV AVI format. Playback is much smoother on your computer as well as on your external monitor if you use one. I made the mistake of converting much of my DV AVI footage to MPEG2 to save space. This is not the way to go. Increase you HD capacity, very affordable at around $1/Gb.

vegasnewbie wrote on 1/25/2004, 10:11 PM

"You are being too conservative. Not only are you making extra work for yourself, but when you separate the rendered versions from the original media, you make it much harder to make any revisions later."

I wondered whether this might be the case. Can anyone give an example of when it might be harder to make any revisions later if you are using several previously rendered avi files in your final combined project. I am not sure on this point.

Thanks, Fred

vegasnewbie wrote on 1/25/2004, 10:14 PM

"These sub-projects, once rendered, become the major elements of my final project VEG. It also allows you to fly through your final project render."

Thanks very much for these interesting comments. I thought a previously rendered avi file might render more quickly when put in the final combined file, but does this reduce the final rendering time significantly compared with one overall rendering of a large project?

Thanks, Fred

Chienworks wrote on 1/26/2004, 4:15 AM

Fred, that depends on lots of things, but generaly it can help a lot. A straight DV -> DV render with no applied effects, titles, etc. can often render much faster than real time. A single change, such as a fade in or a title, can cause rendering to slow down by a factor of 10 or more. So, the benefit of pre-rendering reusable sections is that these massive rendering times can happen only once and then never be needed again no matter how many times you recycle these clips in future projects.

On the other hand, if you do regularly make changes to the parts when reusing them in subsequent projects then this time savings may be considerable lessened. Also, if you usually render to some other format such as MPEG or WMV then the savings in rendering time will be much less too.

So, basically, somewhat yes, but the time savings amount depends on many other factors.

On the topic of wasting time by doing this because it's more difficult to make changes, this doesn't apply if you always reuse your previously rendered clips as-is. My title logo clip took a long time to create, but it always gets used in each project exactly the same way so it makes sense to use it as a prerendered clip. However, if you are using a preexisting clip and decide that you want to have a different transition in part of it, it's almost impossible to do this without going back to the original project, changing it there, and rendering it again. Once you've rendered the clip you've "flattened" it and it's no longer possible to alter the editing choices unless you keep all the pieces and go back into the project.