You don't want to just clip those - it will look ugly and get rejected in the subjective category because of abrupt changes instead of gradual fall off So I'd start looking at using the right tools for the jobįor example, >90% of consumer grade cameras have usable data in the Y 235-255 range. ffmpeg is very useful, but the wrong tool for this (or at least it should be used with other proper tools). Those types of manipulations are nearly impossible in ffmpeg - you need some sort of GUI.
You need to be able to "see" things and get feedback. You need to mask / roto / power windows to control certain areas. You need to keyframe adjustments to do it properly - changes over time. Nobody, ever has perfect lighting and conditions with a perfect camera response - not even in a studio lit, perfectly controlled environment with expensive studio equipment and cameras.
SCOPEBOX 3 NO FILM SCHOOL SKIN
But it's a good way to double check things in spec before exportīut before that, you usually need to make color corrections, adjustments too - fix highlights, fix shadows, correct skin tones etc.ie. That's for quick turn around, don't care too much, just get it in spec. But that is "ugly brute force", no finesse. There are filters that do that automatically (broadcast legal filters). The "better" way is using a NLE for this, that's what everyone uses. Both YUV values that don't "map" to a "legal" RGB value, and things like illegal saturation values There are other levels you need to worry about too, not just min/max values - "illegal" broadcast colors. You wind up sucking too much saturation out of the picture. I found it difficult to bring the R, G and B channels into spec in the YUV domain. If you have a better way of doing it I'd love to hear about it. It's been difficult to achieve but has worked out nicely. This is all checked on a special waveform monitor which reads out the minimum and maximum levels for each R, G and B channel. At this stage I alter the "lift" and "gain" using brightness and lutyuv.
The video is then converted back to YUV 4:2:2 because that is what distributors want. In any event, there must NOT be Y, R, G or B information at 0 or 255 as these values are strictly for sync. Each station resamples from the "contribution" standard for eventual over-the-air broadcast. There are really two standards: a "contribution" standard which is generally at 50 Mbs but is then scaled to a lower bit rate for broadcast, and that depends on how each station has divided its 19.38 Mbps. The 6 Mhz RF channel handles 19.38 Mbps but this is usually divided up between a main HD channel and several SD subchannels as low as, say, 3 Mbps.
we are still using MPEG2 for over-the-air video.
SCOPEBOX 3 NO FILM SCHOOL FULL
So far I've been working in Limited range but plan to experiment with full range to see how ffmpeg behaves. The camcorder puts out levels from 16 - 255. So we are making a round trip YUV -> RGB -> YUV.
SCOPEBOX 3 NO FILM SCHOOL 720P
I then convert it to RGB24 720p because it is MUCH easier to control the individual R,G,B channels in the RGB domain. The camcorder video is 4:2:0 YUV at 1080p. The ultimate objective is to make camcorder video EBU r 103 compliant.
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