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Old 28th June 2021, 15:34   #21  |  Link
benwaggoner
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Quote:
Originally Posted by FranceBB View Post
Well, since we're talking about annoying things from the past, what about overscan/safe area?
To this very day, in 2021, some TVs still crop the image... and for what? Only 'cause back in the days timecodes and teletex subtitles were not muxed but rather displayed in the inactive lines of the screen which were not meant to be displayed to the user... Nowadays, in 2021, everything is muxed, it would be madness to put the timecode or subtitles there when you can easily just mux them in the container, but TVs still crop all around the screen, getting rid of what is actually a part of the image that should be displayed and they do that "just to play safe"...
Overscan can definitely die now. In the Filmmaker Mode spec from the UHDA, we mandated that there be no overscan.

The only content that even nominally benefits from overscan is legacy standard def stuff. And the solution there is simply cropping to 704x480 or 704x576 as appropriate. The eight left/right pixels aren't supposed to be displayed per SMPTE spec, and there's definitely no reason to encode them if they contain non-image content.
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Old 2nd July 2021, 21:15   #22  |  Link
kolak
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Quote:
Originally Posted by FranceBB View Post

- Overshooting
Some light overshoots are still allowed, though. The reason is that, even though you might get the waveform perfectly fine in Avisynth, once you encode with a lossy codec, the approximations that are gonna occur might lead to overshooting, so slightly out of range values. This was very much true for MPEG-2, but way less pronounced for H.264 and H.265, but it still occurs, which is why nobody is gonna tell you anything if you get some light compression overshooting every now and then.
Not only heavy compression overshoots, but intermediate codecs as well (ProRes, DNxHR etc). Quite often it's good few levels (of course on high contrast areas).
Not a big deal in current digital world. Broadcast freaks out about it for no real reason (it was a real problem in analog era, but not now).

Good that EBU R103 got updated. Key point is in line 2:

"The EBU, considering that,
• video levels have traditionally been measured with devices that display a trace, such as a traditional waveform monitor,
• that readings in mV no longer give relevant information in digital signal infrastructures,
• television systems now include high dynamic range and wide colour space images as well as
standard dynamic range and colour space images in the same digital container,
• that a certain tolerance can be allowed in digital signal levels,"

mV should be gone. They serve no role anymore. It should be either % of signal or simply levels per given bit depths.

Last edited by kolak; 2nd July 2021 at 21:25.
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