which prerender format?

megabit wrote on 6/22/2008, 3:50 AM

I wonder which format are you guys using for selective prerenders with projects, involving HQ 1080p clips from the EX1?

My final encodes are almost exclusively 1920x1080 MPEG-2's for BD delivery.

For prerenders, do you use MPEG-2 or AVI? Pros and cons, please...

PS. I guess I should have included theimportant information, that I edit native mxf (long GOP, not Cineform or alike)

Comments

rmack350 wrote on 6/22/2008, 10:23 AM

Generally, I'd say No to mpeg2 and Yes to Sony YUV avi

Unlike many other NLEs, Vegas gives you a lot of choices. You'd think that would be good but in practice it leaves the decision up to each and every user.

Typically, the whole point of a prerender is to allow you to see your effects and transitions in real time. For that, something like Sony YUV ought to do the trick because it's fast to render and compact enough to play from a single hard disc. DV-AVI compression might be enough but it introduces some artifacts in graphic elements that you might not want to see, and uncompressed AVI looks great but takes up too much space.

Vegas introduces an added wrinkle of "no-recompress" renders, where it just copies data to the new render wherever possible. You should test to see if this comes into play when going from prerendered footage to a final render. If it does then there might be an advantage to doing prerenders in your final output format, but creating prerenders in MPEG2 MUST be slower than making them in a legitimate intermediate format like Sony YUV, huffyyuv, cineform, etc.

Even if prependers in mpeg2 works out, I'd rather choose one intermediate format and then forget about it.

rob mack

megabit wrote on 6/23/2008, 9:17 AM

Thanks Rob,

You say:
[...] something like Sony YUV ought to do the trick because it's fast to render and compact enough to play from a single hard disc. [...], and uncompressed AVI looks great but takes up too much space

Well, unless I'm missing something, it's abit defferent here with my system. First of all, when I render to Sony YUV, I'm getting an uncompressed file (at least so Vegas says about it's properties). Also, while rendering to MPEG-2 (exactly the same format as my intended output) is much, much faster than to Sony YUV - for some reason, Vegas can use up to 100% of my Quad CPU, while it only renders at some 30% to AVI.

Finally, the Sony YUV is NOT "compact enough" to play from single disk - in fact, I can only play it back at full framerate from my new RAID 0, which is reported by HD Tune as capable of transfers exceeding 200 MBps. And this is the reason I never used rendering my heavily edited areas to uncompressed format before - none of my disks (one performing around 50-60 MBps, the other some 110 MBps) was fast enough to give me smooth playback, thus denying the very purpose of pre-rendering...

But since I hear many people are using uncompressed HD, it makes me wonder if everything is OK with my system - isn't a 100+ MBps disk fast enough for that?

This question is even more important to me now, as - prerendering aside - I will be using files from Flash XDR soon; will the long-GOP 100Mbps 4:2:2 play back smooth enough? Or should I be thinking about replacing my slower RAID 0 with another, at least as fast as the other one I have now (i.e. 200+ MBps)?

rmack350 wrote on 6/23/2008, 1:57 PM

Erm, sorry, you're right that an uncompressed 4:2:2 sampled AVI in HD probably won't play back without RAID. As far as Sony YUV being compressed or not, good question. It's certainly not as fat as 4:4:4 uncompressed, but I was assuming it was at least RLE compressed.

If SonyYUV isn't compressed, I'm sure there's something else available that is 4:2:2 and also compressed. Cineform, for sure, and something DVCPro100-ish also fits that description. Obviously SonyYUV wouldn't be a good choice.

You need to do some testing to figure out what to use. MPEG2 is generally considered a delivery format, not an editing format. However, if Vegas can take your mpeg2 prerendered segments and stitch them together without recompression then you've got a solution that fits this one particular application. It's not a universal solution and would be useless if your final product were something other than mpeg2.

Outside of the HDV and AVC consumer realms, people often do indeed use RAID arrays providing more than 200 MBps throughput, but the goal here is to prerender to an efficient editing codec that's generally useful for you in Vegas on consumer gear - a single drive.

As far as SonyYUV being slower to render than MPEG2...my first guess would be that your quad is being limited by your disk speed. But maybe there's more to it than that.

Rob Mack