Smart rendering in Premiere Pro has been available for DV and DVCPro formats for years. In Premiere Pro CS6 (6.0.1, and later), smart rendering capability has been added for Long GOP MPEG2 OP1a exports, where the original material is a matching long GOP MPEG2 OP1a or XDCAM EX file. The intention is that smart rendering creates better quality output by avoiding recompression when possible.
Update Premiere Pro CS6 to get the full benefit of this feature.
Premiere Pro engineer, Wil Renczes, explains how smart rendering works in Premiere Pro CS6 (6.0.1, and later):
What is it? (probably obvious, but I’ll start at the beginning):
The feature is specifically for accelerating MXF render times for long GOP MPEG2 essences, while avoiding recompression.
Which new formats are now accelerated?
Source media that is either XDCAM HD in an MXF wrapper (ie 4:2:0 XDCAM HD @ 18/25/35 mbits/second, or 4:2:2 XDCAM HD @ 50 mbits/sec.), or XDCAM EX (.mp4 wrapper within a BPAV folder structure, 18/35 mbits/second).
What do I have to do for it to work?
Nothing for DV or DVCPro formats, smart rendering automatically engages. For XDCAM formats, check the checkbox for smart rendering in the XDCAM exporter plug-in. If you have these types of clips in your timeline in a sequence with matching settings, are exporting out to MXF OP1a with a matching preset, and the checkbox is checked in the XDCAM exporter plug-in, it’ll engage. It’ll also figure out if there’s any effects applied and fall back to regular rendering if needed.
Can I turn it off?
Uncheck the checkbox in the XDCAM exporter plug-in.
How do I know it’s working?
Excellent question. Since it’s supposed to work seamlessly, there are no hints in the UI as to what’s going on. As an engineer, we can check out conflicts in a debug console window. If there are any mismatches, then smart rendering won’t occur. Unfortunately for the user, there is no way to test if smart rendering is working other than noting an accelerated workflow, and less generational loss.
What kind of acceleration are we talking about exactly?
Well, the idea is that for untouched clips, recompressing frames is probably going to take longer than simply copying the data directly from the source clip. Now, it’s not quite as simple as that, as if you have edit points that don’t land on I frame boundaries, then there’s some partial GOP ’healing’ that needs to happen, but we don’t need to get into the nitty gritty here. Anyway, provided you have good disk i/o, the render numbers are a fair bit better.
Testing indicates that the render numbers are anywhere from 4x to 12x faster than realtime. On my own benchmarks (off a single drive, SATA 3 mind you, but still), a regular render of XDCAM HD 4:2:2 at 50 mbits is usually 2x realtime. With smart rendering enabled, the same clip now renders at 6x faster. Not too shabby. And, the lower the bitrate, the faster it renders (less data per frame to copy, so it can do more at the same transfer speed).
Okay, I’m trying to smart render an XDCAM EX clip out to OP1A, and why isn’t it smart rendering?
This is probably the trap that most people will fall into when trying it for the first time. For example, if I pick an EX clip, 35 mbits/sec, shot at 24fps. Then, I drop it into a matching sequence, pick the XDCAM HD 1080 35 NTSC 24p preset, and hit render. However, if I check it on the console, I see errors.
Why the heck is that?
XDCAM EX footage is at a full 1920 x 1080 raster size. XDCAM HD 4:2:0, on the other hand, is actually 1440 x 1080 with a PAR adjustment. So we can’t smart render this, the frame sizes are different.
Wait a second, didn’t you say that EX is a supported smart render format!? Quit foolin’…
Why yes, it is. It’s just a problem with the preset. We don’t have prebuilt presets for EX material in the OP1a exporter’s list of available presets to choose from, so if you want to smart render EX material, you’ll need to create a preset with the right settings. So, going back to my example, if I go to the Video Settings and look under the Video Codec list, and pick XDCAM EX 35 NTSC 1080 (4:2:0), now it’ll smart render.
Well, that’s a little confusing.
Agreed. The feature really was initially meant for XDCAM HD workflows, which you have all the presets available for. The EX was kind of a bonus request that we threw in based on a specific request from a broadcaster.
What other kinds of errors will potentially bork smart rendering?
Weird ones: mismatches between your source media & the settings you pick to render out to – things that aren’t immediately obvious (but the console window will tell you). For instance, your source file’s MPEG GOP structure doesn’t match the destination, or the source is VBR but you picked a CBR preset, or the bitrate is too different, or there’s a frame size mismatch. All these conditions will make it fall back to regular rendering.
Will this smart render take advantage of my preview files so that my final render is that much faster?
Sadly, no. We’d have to enable XDCAM HD as a preview format option, but then yes, this would suddenly work. Great feature request, feel free to pass it along! (Make a feature request here: http://www.adobe.com/go/wish).
Thanks to Wil Renczes for the content of this post.Share on Facebook
