HDR to SDR Encode

[iKron]

Video source is x265 HDR 2160p, i want to convert it to SDR 1080p. here is something i found that we can convert HDR to SDR. but will the color looks good? or better use 1080p SDR source for encode? my main goal is to encode in small file size.






currently i already using

colorprim=bt709:transfer=bt709:colormatrix=bt709

according to the stackoverflow suggestion i have to use `format=yuv420p10le` to make HDR to SDR. will bt709 make any kind of conflict?

https://stackoverflow.com/questions/61460247/10bit-hdr-to-10bit-sdr-conversion-with-ffmpeg

[ProWo]

10bit isn't necessary, you can go to 8bit also.

[TE16]

The HDR content will need to be tone mapped to SDR. It is not as simple as encoding the content with colour options set to BT709. I don't know enough when it comes to tone mapping however I have used Hybrid in the past which worked successfully for tone mapping. I know that in someway StaxRip can also do tone mapping. Might be worth trying out either of those programs so you can analyse the scripts they create for HDR to SDR tone mapping.

[butterw]

The UHD source is generally preferrable, but the result of HDRtoSDR tonemapping might be quite poor, in which case the 1080p SDR authored source would be the better choice.

You could encode as HDR and do the SDR tonemapping at software playback also.

[jagabo]

HDR to SDR with AviSynth:
https://forum.videohelp.com/threads/399320-Converting-BT-2020-down-to-BT-709#post2600628

uses DGTonemap:
http://avisynth.nl/index.php/DGTonemap

[iKron]

okay thank you all, i will try the suggested method.

[jagabo]

The result using the command line from the stackoverflow link was pretty close to the AviSynth script I gave. Whether or not the official SDR release looks better depends on how much effort they put into it.

[JKyle]

FYI, refer to this GitHub Wiki document for how to convert HDR to SDR in StaxRip.

[iKron]

thank you @JKyle @jagabo for the suggestion.