I take no offense and I hear absolutely nothing snide in your response. Heck, you didn't even mention a shotgun.
> There will be other things done in the Avid world and it may see light other than just the web.
Aha. I must have missed that in the blog.
>... so you end up having to take an approach that works in actual practice beyond the theory of it all.
Yup. Actual practice trumps theory, and I'm just theorizing, true.
> The image will be destroyed. Don't do it. Although I have seen people advocate this. What happens when you start mixing other footage into the sequence, like pick-up shots done with some other camera?
"will be destroyed" sounds pretty absolute. How? In the HDCam to DI to film stages? Or just because it's a sloppy way to work? Good point about mixing in other footage, though--there's already talk on this project of shooting film and of using an EX3. Start mixing in other video sources and I can see it's quickly not worth any incremental gain from playing with levels.
> In the end, remember Avid is NOT a DI tool.
Well, no, but it's gonna get used as one. And if I can figure out the limitations and how to make it work, I get the work.
> It doesn't matter. You are starting with a 4:2:0 signal.
And yes, this is where my mental exercise failed. My thinking was that the Avid codec's higher bit depth would help avoid banding and posterizing once the footage started getting pushed around. But if I had, say, a two-bit source image with just four levels of brightness, then that higher bit depth of the new format would give me more options to push those four levels toward, but there'd still be just four levels. I get that.
>In actual practice, the image from a Sony EX3 will have more true resolution and less visible artifacts than the Canon, once you see it on a big screen. I can personally attest to that. In actual practice you could cut this as DNxHD145 or DVCPRO HD and be fine. Dump it to HDCAM-SR, take it to a DI house and do a trim pass for film. If you really want to squeeze the last little bit out of the image (of which there isn't any), dump the Canon files to DPX image sequences and grade/DI on Lustre, Pablo or Scratch.
Advice from someone who's done it; that's why I'm here. Thanks. And I see you just updated the blog entry on posting with Canon 5D footage--great! I've been waiting for that.
-Bill
--- In Avid-L2@yahoogroups.com, Oliver Peters <oliverpeters@...> wrote:
>
> Hi,
>
> > wllm_meese wrote:
> > So Oliver; why remap to 709? If the goal is to import and export through Avid as transparently as possible, why not choose 709 in and out?
>
> True, if all you were concerned about was a single pass through Avid without any further post. My intent is to cut normally in Avid, not just a roundtrip. There will be other things done in the Avid world and it may see light other than just the web. Canon files import correctly as RGB. So Canon into Avid should be RGB. The rest of it was to see what the right steps would be to get that end product - whatever it ends up being - back into FCP (if need be) with a result that would closely match other post done on other Canon projects in FCP.
>
> If I import as 709, the levels will get improperly clipped throughout other post processes, such as color correction or applying safe level filters. Remember, I'm not just cutting spots, but color grading, applying effects filters and so on. Also, the image does not look right (imported as 709) as I'm cutting, which is far more important to me.
>
> > The previous thread about QT import points out that this avoids the remapping, which must have some effect on the image.
>
> True, but I feel that's a simplistic solution, which doesn't take into account all the rest of the things you do in post. It's not how you "cheat" the system, but rather how you get it to behave properly - or at least as expected. The Canon levels aren't RGB per se, but only RGB as they relate to how QuickTime displays these files. Canon isn't really saying. There's no way of knowing whether they really are RGB natively (though I presume they are). In fact, the codec would predict the levels should actually be 709. BUT they aren't.
>
> Part of the solution is codec-dependent. For instance, my export of Avid 1:1x straight into FCP worked, but then it crashed FCP when I had to render it. Export out of Avid as ProRes caused color shifts. FCP does NOT properly honor either an RGB or a 709 color space mapping, so you end up having to take an approach that works in actual practice beyond the theory of it all.
>
> > The Canon records RGB levels. If we import footage flagged as 709, edit & grade in the Avid, and export as 709 to a file (or image sequence) for film out, would we be retaining more bit depth in the image?
>
> The image will be destroyed. Don't do it. Although I have seen people advocate this. What happens when you start mixing other footage into the sequence, like pick-up shots done with some other camera? In the end, remember Avid is NOT a DI tool.
>
> > In other words, we'd be grading with a full 1024 steps instead of just 876 (do I have the 10-bit math right for 7.5-100 IRE?).
>
> It doesn't matter. You are starting with a 4:2:0 signal. Plus, you are comparing grading levels to bit-depth and they aren't the same. If this is for actual film-out, your video-based grading won't be accurate anyway for the film image.
>
> > For any video output, we could just drop a color correction effect on a top track with a curve to squeeze levels to 709.
>
> This *could* work in theory, but I submit that it isn't the right approach. It's not simply about level-mapping. You would be trying to mimic a LUT.
>
> Please don't take offense, but I think you are over-thinking this. I hope this doesn't sound snide, but remember you are starting with a highly compressed image in 4:2:0 color space. In actual practice, the image from a Sony EX3 will have more true resolution and less visible artifacts than the Canon, once you see it on a big screen. I can personally attest to that. In actual practice you could cut this as DNxHD145 or DVCPRO HD and be fine. Dump it to HDCAM-SR, take it to a DI house and do a trim pass for film. If you really want to squeeze the last little bit out of the image (of which there isn't any), dump the Canon files to DPX image sequences and grade/DI on Lustre, Pablo or Scratch.
>
> - Oliver
>
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