Comments

Laurence wrote on 5/14/2007, 10:48 AM
Bump plus a little more:

When you selectively prerender video, you can see the parts that are selectively prerendered just above the timeline. If I do this in a SD project, these blocks appear just above the transitions as they should. If I do this with an HDV project, the whole timeline has blocks above it. In other words the whole timeline is selectively prerendered.

Is nobody else running into this?
Laurence wrote on 5/14/2007, 11:34 AM
Even stranger:

1/ Lets say I put a single Cineform codec 1080i codec clip on the Vegas timeline. No transitions, no filters, no opacity, etc.

2/ I "selectively prerender" the project. Nothing should be selectively prerendered. I watch the preview window. It stays black the entire time indicating that any part of this clip that is rendered was smartrendered. When the selective prerender is done, blocks appear above the timeline indicating that the entire clip was prerendered.

3/ I press play and find that the preview efficiency is much better. CPU usage drops way down and I can now preview with no dropped frames at the "best" preview setting even though I have an older P4 3.06.

4/ I find the "selectively prerendered" temp files on the hard drive and copy them to the timeline to see if they play as well directly as they do when used for selective prerender playback. They don't. They only play back as well as any other Cineform clip that hasn't been "selectively prerendered".

All this leads me to three questions:

1/ Why does Vegas rerender the entire timeline instead of just the modified parts in HDV projects.

2/ why does an unmodified Cineform HDV clip play back so much more smoothly after it's been "selectively prerendered" even though nothing in the files have been actually changed?

3/ Selectively prerendered footage plays back incredibly well with incredibly light cpu usage. Why can't regular Cineform playback be this good? After all, the files are EXACTLY the same format!
Laurence wrote on 5/15/2007, 7:36 PM
Bump. I'm amazed that no-one else is complaining about this. As far as I can see, selective prerender doesn't seem to work properly in HDV at all. It works fine in SD where I have plenty of power and don't really need it, but not at all in HDV where my CPU is struggling to keep up and it would be genuinely useful.
winrockpost wrote on 5/16/2007, 5:25 AM
good point,, er points,, prerender wont work unless some flavor of avi
useless for hdv, unless intermediates, which i think you also find has a gitch
Grazie wrote on 5/16/2007, 5:48 AM
Laurence? I guess you ARE selecting the correct template for Pre-rendering? Yes? Just thought I'd confirm this with you.

G
frazerb wrote on 5/16/2007, 5:53 AM
I have noticed this phenomenon, but assumed that m2t files had to be re-rendered even if the edit was cuts only. I expect this might be due to the inter-frame compression of the m2t (mpg) file.
Buddy
ForumAdmin wrote on 5/16/2007, 6:36 AM
.m2t files have to be re-rendered even if the edit was cuts-only.
Laurence wrote on 5/16/2007, 6:58 AM
Yeah I understand with m2t files, but not with smart-rendering Cineform codec files.

Yeah, I am setting up the format exactly right. I even did that cool function where you can derive the format from a file. Boy is that a cool feature that I only just noticed! Anyway, the Cineform files smart-render all the parts where there are no transitions, so it doesn't take that long, but it still eats up gobs of hard disc space that it shouldn't need to.

I don't mean to go on about this, but with a trailing edge system such as mine, being able to selectively prerender the project would make editing an HDV project way more pleasant.

In the mean time, I can work around this by looping the parts I want prerendered and selectively prerendering them one by one, but it takes extra time and I shouldn't have to.
epirb wrote on 5/16/2007, 11:59 AM
I wonder if it has something to do with Vegas using VFW and Cineform using Direct Show. I asked David about this in another thread he said that quality is no diferent but that when rendering from the vegas t/l it will rerender to the VFW codec or something like that.

Nope scratch that idea... just rendered to a new track in Vegas, that should eliminate that issue. it still prerenders even the Vegas rendered new track section.
Laurence wrote on 5/16/2007, 1:53 PM
Yeah, I tried both by rendering in Vegas and selecting the "smartrender in Vegas" tab in HD Link. The VFW version smart renders so quickly that it is more of a disc space than a time problem.

By the way, did you notice how well the prerendered sections preview? It's just incredible. My P4 3.06 kind of struggles along with cuts only Cineform at preview resolution without aspect ratio scaling. Selectively prerender the same section and I can preview at best resolution with 16:9 scaling at about half size with about 40% CPU usage. If I go into the temp files directory and copy the same files that were used for the selective prerender to the timeline, the performance drops back to what it was before the selective prerender. I don't mean to go on about this, but after a selective prerender, my P4 gives a better preview than my friend's dual core! You guys really need to try this. It will amaze you.