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5Dmkiii footage: Will values >235 be clipped?
Hello, I’m haveing a hard time wrapping my head around color spaces etc. I edited native h.264 files in FCP7 (I know, bad move…I figured out after the locked edit why it was so slow). The footage was shot with a 5Dmkiii and the zebras were set to peak at 250 so I wouldn’t have anything blown out. My end goal for the project is to output to TV and not online…what I have read in many different articles is that the RGB color space can show values between 0 and 255 and that output for TV or Broadcast is less than that. Does this mean that anything above the value of 235 (all of the highlights I was cautious about preserving) will be blown out? Please help me understand how this works and if there is anything I can do to retain the highlight data. Do I need to switch the settings in the video processing to RGB?
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4 Replies
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You need to be looking at scopes and at the IRE levels. Anything above 100 will be kicked back illegal. Levels can go as high as 110 IRE before they start blowing out, but 100 IRE is the legal limit allowed for broadcast. And you judge “blowing out” by your eye looking at the image, not the scopes.
And TV is YUV, not RGB, so stick with YUV. And make your sequence ProRes 422 right away. At least render to ProRes if you aren’t going to convert the footage.
Shane
Little Frog Post
Read my blog, Little Frog in High Def -
Shane, thank you for your guidance on this. I am thinking the smart thing to do would be to get into Prores 422. Would the best bet be to batch convert all of the files via 5DtoRGB (full values) and then use “Reconnect Media” in each sequence to the new MOV files? Or should I just move the old files into a new folder and batch the ProRes files to the same folder so they will connect automatically. Wouldn’t this be the better option rather than only rendering what’s in the timeline in case I have to re-edit several whole scenes down the line with different takes?
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You might have issues reconnecting if you do that. Timecodes might not match up. You can try, as that is the best quality conversion…but it takes a while. Do a couple clips only, see if they reconnect properly.
Shane
Little Frog Post
Read my blog, Little Frog in High Def -
You have to worry about the shadows too, not just the highlights, as video can be too dark as well as too bright. On a waveform monitor a legal digital signal will have a range of 0-100. This corresponds to a range of 16-235 in computer values if you are working in 8-bit media (and the media from your camera is 8-bit). RGB (color space) and bit depth (8-bit, 10-bit, etc.,) aren’t the same thing, but that’s a whole other post.
Basically, if you are looking at a waveform monitor, cameras can record at values below 0 and above 100 so you have wiggle room in the field while shooting. When it comes time for broadcasting though everything has to fit between 0 and 100 for compatibility reasons. If you don’t raise the blacks to at least 0 and lower the highlights to at least 100 then those values that are out of bounds will automatically get cut off with possibly ugly results (ex. a soft white glow that goes beyond 100 might get an ugly yellow halo after it is automatically clamped down to 100).
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