Questions about pre-rendering

sean@oregonsound.com wrote on 7/21/2007, 3:17 PM
Hi all. Is it a safe assumption that pre-rendering a section of a video to reduce CPU load will suffer absolutely no degradation so long as it is uncompressed AVI or MOV? Any advantage or disadvantage to one format over the other?

Also, when doing this, is there a way to hold onto all the CPU-hungry clips and their associated effects, say on unused muted tracks, that would not continue to tax the computer?

Comments

jetdv wrote on 7/21/2007, 6:22 PM
If you're starting with DV and ending with DV, prerender to DV. How about a little more information?
sean@oregonsound.com wrote on 7/21/2007, 6:28 PM
Mostly presentations made up of still images (have been using JPEG but now switching to PNG), with lots of transitions, panning and effects. Not too many video clips, which have generally been AVI. The stills include a number of hi-res scans and hi-res digital photos, so I'm concerned about the slightest loss of quality when these are projected onto a large screen.
jetdv wrote on 7/21/2007, 7:24 PM
What's your final output? You might consider pre-rendering to DV-AVI.
Chienworks wrote on 7/21/2007, 7:40 PM
The final resolution will be that of the output format. If you're rendering to DV or for DVD then your resolution will be 720x480 (for NTSC). So, you're probably already losing most of the resolution from the hi-res scans and photos. Vegas can render up to 2048x2048, but i don't know what you'd use to play that back. For that matter, *most* projectors are only 1024x768 or less.
sean@oregonsound.com wrote on 7/21/2007, 10:01 PM
These are always ultimately rendered to mpeg-2. Thanks for the info about the still resolutions---I'll keep that in mind. I'm really only concerned with maintaining highest quality before final rendering, and want to be sure that any sections I replace with pre-rendered, uncompressed AVI don't cause any unnecessary degradation prior to the "necessary" degradation during the mpeg-2 compression.
UKAndrewC wrote on 7/22/2007, 10:06 AM
There is no advantage to uncompressed AVI or MOV as they are the same format.

You could use a lossless AVI compression such as huff, if you want to save disc space.

I just create my prerender as another project and keep that.

I always rescale my images to the output size in a graphics package as they usually do a better job, and save as lossless PNG.

Andrew