just a technical discussion in the process of yuv->mp4

[sunzuoxiao]

hi, sooyekim:

i want talk some problem with you in the process of yuv->mp4 by ffmpeg

I download a hdr.webm video from youtube, than,first , used ffmpeg commad:

ffmpeg -i hdr.webm -pix_fmt yuv420p10 hdr_1920X1080_10bit.yuv

second,

ffmpeg -s 1920X1080 -r 60 -pix_fmt yuv420p10 -i hdr_1920X1080_10bit.yuv -r 60 -crf 5 -c:v libx265 -x265-params "colorprim=bt2020:transfer=smpte2084:colormatrix=bt2020nc" -y hdr.mp4

I thought the two video(hdr.mp4, hdr.webm) should look like same, but i'm wrong, hdr.mp4 is dark than hdr.webm.

even i add or change metadata like:

"colorprim=bt2020:transfer=smpte2084:colormatrix=bt2020nc:master-display=""G(12250,35150)B(6899,2600)R(33899,16099)WP(15634,16449)L(10000000,0)"":max-cll=""1100,180"":min-luma=0.0000:max-luma=1000"

hdr.mp4 still more dark, I don't know what caused it. can you give me some advise, thanks

[sooyekim]

Hi @sunzuoxiao ,
First of all, are you sure the original hdr.webm file is encoded at BT.2020 with PQ-OETF and 10 bits/pixel?
There can be HDR videos in other formats than this. To me, it seems like it could be a different HDR format, which could be why the colors look different when forcing x265 to wrap it in BT.2020.
Also, how are these frames captured? Have you tried viewing the videos on an HDR display?