Uncompressing/uprezing?

[Lucian]

Does anyone do this as part of their grading workflow?  Someone mentioned to me they do it

with their dslr footage so as to work in the best possible color space for manipulation. I'm totally

unfamiliar with this concept, if anyone can elaborate I'd appreciate it.

 

Thanks in advance.

 

[Andrew Reid]

You can't uncompress compressed video, the data is lost forever.

 

Upscaling is a different thing. DVD players used to do it. Standard definition DVDs to 720p. Sony's 4K TV will do it with 1080p. I don't know of any plugin or workflow for Premiere, Resolve, Final Cut Pro, etc. that does it. I find that a glaring omission in the editing world!

[Lucian]

Hey Andrew, I believe the uncompressing is not aimed at reclaiming lost data, rather opening up

a higher color bit depth to give the highest possible color space for grading. This may be a redundant

step with hacked gh2s, I don't know.. thats why I was curious if people were using this as part of their

grading workflow.

 

Cheers

[Andrew Reid]

No, that theory is discredited unfortunately.

 

If you convert compressed H.264 to 10bit ProRes, it is the same to grade as the master files. Transcoding gains no extra image quality. I once read a very good blog showing this but unfortunately I forget the source. Unless you're trying to fix a compatibility issue like 5DToRGB did with GH2 footage and Quicktime on a Mac, you're best off dropping the original native clips straight into the NLE.

[Lucian]

I see, well that answers my question, thanks :)

[andy lee]

the hack on the GH2 gives you bigger files with LESS compression in the AVCHD codec

I run mine at about 170mb/s so the files are big over a gig per minuite shooting time

But the amount of detail retained in the files is quite amazing

I've sat in commercial edit suites grading stuff and you would be suprised at now much latitite there is in a hacked gh2 file

for grading .

The suite I use regularly work on Red Raw and ARRI Raw and the Gh2 is close to them in the amount of latitiute

the files have for grading

so my advice is get a mega hi bit rate hack on your gh2.

[Sean Cunningham]

There are techniques in chroma filtering that can help reduce the impact of what was lost in both the compression and subsampling.  The GH2 doesn't need as much filtering as Canon cameras but there are plenty of cases where footage can be enhanced prior to, or in conjunction with, the grading process.  

 

This is where dedicated grading packages (including AfterEffects) will outperform staying within the editor for grading, regardless of their advertised bit depth and precision.  It's very easy to exacerbate the damage done in-camera at the compression step by processing both the luma and chroma of your footage simultaneously at every step.

[jgharding]

Basically, if you wanna grade, you can do it natively without transcoding, if the software you have can handle the file format.

 

As long as the engine is "floating point" like DaVinci Resolve or After Effects (if you set the project bit depth to 32-bit) you're getting the best you can.

 

As Sean says, use a piece of software designed for finishing and you get the best results, usually, because the engine is geared towards quality, not speed. I do grades in Premiere if a project needs a quick turn around, but otherwise use some dedicated post software.

 

DaVinci Resolve has a steep curve to learn, but it's worth it. 

 

The software will be ubiquitous pretty soon.

[Lucian]

Yes after some more research it seems that it is indeed beneficial to make sure you are working in 32bit color space even

if the footage was originally 8bit. In addition it seems some folks are uprezing to 4k to apply sharpening and grain.

 

Cheers