5D to RGB Batch Converter

Glenn Przyborski

Glenn Przyborski

Member
Hey Folks... Maybe this has already been discussed, but I've found what appears to be a simple solution to the AF100's chroma clip on highlights problem. It's the newly updated 5D to RGB batch convertor from Rarevision. (http://rarevision.com/5dtorgb/)


The new "batch" version was updated to handle AF-100 AVCHD files (including audio) The program yields excellent ProRes422HQ files that are much better than Final Cut's "log & transfer" file importer. The conversion is slower than "log & transfer", but the extra time is well worth it.


The resultant video files have the proper levels and the highlights appear to be clean and clip at 100%. You can get the updated program in the Apple App store for $49.95. I believe there is also a Windows version.
 
I looked for a windows version of the batch converter, and didn't see it. They only have a windows version of the old non-batch 5DtoRGB Lite.
 
I've posted 2 identical, ungraded, full-resolution frame grabs. The first was converted to ProRes422HQ by Final Cut's "Log and Transfer" function…


http://www.przyborski.com/TEST/ProRes422HQ via FinalCut.png


The second image (from the identical original AVCHD frame) was converted to ProRes422HQ via 5D-RGB-Batch…


http://www.przyborski.com/TEST/ProRes422HQ via 5DRGB.png


Note the highlights on the right side of the dish. You can see from the scopes that Final Cut hard clips at 110% and the chroma signal clips even higher. Once your luminescent signal rolls into hard clip, the chroma portion of the signal must also roll into clipping at this same level. Otherwise, you get a false color in a scene's highlights.


This problem was discussed over and over in this forum shortly after Panasonic began delivery of the AF-100. It's not the fault of Final Cut as the same high signal levels are present on the camera's HD-SDI output when displayed on our Leader or Harris SDI signal analyzer. (FYI: Neither the GH1, GH2, 5D Mk2, or 7D exhibit these high signal levels.)


The scene I selected is not a great example of the problem, because the clipped white areas have chroma that's similar to the color of the bowl. In other lighting situations, the specular highlights might look teal or yellow. It can easily happen if you have your camera's color balance intentionally set to yield a cold or warm scene.


If your goal is to upload videos to Vimeo or You-Tube, this really isn't too much of a problem. However, if you're producing on-air, HD material for file delivery to television stations or services like DG/Fast Channel, your video signals should always be within established technical standards.


Note the 5D to RGB settings were: ProRes422HQ, ITU-R BT.709, Bake Gamma Correction. Gamma Flagging & Post-Processing set to "none". Chroma mode set to "default".
 
Is this doing anything other that what could be achieved in post with a little tweak of the highlights using the 3-Way colour corrector in FCP?
 
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