[Cin] HDR footage from images via ffmpeg

[Andrew Randrianasulu]

ср, 31 мая 2023 г., 14:09 Andrea paz <gamberucci.andrea at gmail.com>:

> > is HDR basically "some 8 or 10 bit tech + wide gamut light emitting"?
>
> I am not familiar with HDR. All I know is theoretical and dated
> (Brinkmann's book on compositing).
> HDR can only be in floating point, using a normalized color range (0-1
> instead of 0-255, etc.). In fact in floating point it is possible to
> have values above 1 while in 8, 10 -bit it is not possible to have
> values above the limits.
> Upon receiving an HDR video signal, there are algorithms to map and
> balance these values on SDR or HDR displays. This is called tone
> mapping.
> To summarize it is necessary:
> 1- An HDR video signal (usually obtained by merging multiple frames at
> different exposures).
> 2- A tone mapping tool
> 3- A suitable display (usually high nits, i.e., brilliance)
>

So, may be due to 1) modern smartphones have so many cameras!



I am looking at shotcut forums just for inspiration

https://forum.shotcut.org/t/hdr-support-export/29666/11

====

Any editor working in HDR needs to be able to import BT.2100 HLG, BT.2100
PQ, BT.2020 and BT.709 files and map them to a common timeline format,
output to those 4 formats, and allow the user to calculate the HDR10
metadata if you choose to have a PQ output format (this isn’t automatic as
you need to know the gamut and peak brightness of the monitor you edited
on).

===

https://www.voukoder.org/forum/thread/1005-good-x265-settings-mar-2022-update-merged-to-v11-1/

=== quote ===

*HDR Support (x264 & x265):*


*Tagging DCI-P3:* --master-display
G(13250,34500)B(7500,3000)R(34000,16000)WP(15635,16450)L(?,1)

*Tagging BT.709:* --master-display
G(15000,30000)B(7500,3000)R(32000,16500)WP(15635,16450)L(?,1)

*TaggingBT2020:* --master-display
G(8500,39850)B(6550,2300)R(35400,14600)WP(15635,16450)L(?,1)

The L(?,1) indicates lux ratio (e.g., 1000:1). This value has no standard
and needs to be checked and written manually on each HDR video.


If tagging for the source vid is unknown, find 1 of the following format in
source video metadata:

DCI-P3: G(x0.265, y0.690), B(x0.150, y0.060), R(x0.680, y0.320),
WP(x0.3127, y0.329)

bt.709: G(x0.30, y0.60), B(x0.150, y0.060), R(x0.640, y0.330),
WP(x0.3127,y0.329)

bt.2020: G(x0.170, y0.797), B(x0.131, y0.046), R(x0.708, y0.292),
WP(x0.3127,y0.329)


*Content lumiance x265: *--max-cll <max content light level cd/m2, max
frame-avg light level cd/m2> e.g., 1000,640

*Content lumiance x264: *--cll <max content light level cd/m2, max
frame-avg light level cd/m2> e.g., 1000,640

CLL has no standard and needs to be checked and written manually on each
HDR video


*Indicate HDR10 content in supplemential enhance info (SEI)**, x264 **: *
--hdr10


*Optimize HDR10 content (increase video size) per block (optional, x264
[image: :(] *--hdr10-opt


*Indicate color range and transfer properties: *--colormatrix <as source>
--transfer <as source>

Color range can vary thanks for both compatibility and multple HDR
implementations, (e.g., gbr bt709 fcc bt470bg smpte170m YCgCo bt2020nc
bt2020c smpte2085 ictcp). Check the source video metadata for them


====

https://stackoverflow.com/questions/69251960/how-can-i-encode-rgb-images-into-hdr10-videos-in-ffmpeg-command-line

this answer says mastering-display is NOT for your editing display but for
ideal viewing display! Are they supposed to be the same?

Not sure how you calculate max-cll et all from your display / source ...
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