coding vvc for best psnr and ssim value

[Diyari90]

thanks for your answer me.

a) I encode my .y4m video to h266 by this command line (ffmpeg -i -c:v vvc -b:v 20M -qp 0 -preset faster

) b) i want to psnr the video encoded with my y4m but the result is (17.6...) not as i expecting it c) i have warning in timebase difference i fixed in h265,264 by this (-vsync 0 -enc_time_base -1 -video_track_timescale 60) this parameter not work in vvc not know why it warning me -vysnc is deprecated you should use (-fps_mode ), then i will change my command line to this ( -fps_mode vfr -enc_time_base -1 -video_track_timescale 60) still i get same warning my time base deffrente frist input 1/12000 and second input is 1/60.

i searched on internet and looked at those issue in GitHub i couldn't resolve my problem i didn't got anything so i hope answering my 3 issue i wrote it

[jungleboynx]

The qp value is approximately the average B-SLICE quantizer. The I-SLICE is about 10 lower which means the lowest qp is about 10 if that's any help. It's not possible to create lossless Intra frames only like x264 or x265. The bitrate for the I-SLICE is spread out over 8 B-SLICEs (I think) to reduce the peak bitrate.

[Diyari90]

@jungleboynx the bitrate isn't any problem i will just remove it and left it for default ,my problem is when i do psnr and ssim it give me less value like raw video and encoding is deferent video

[adamjw24]

a) I encode my .y4m video to h266 by this command line (ffmpeg -i -c:v vvc -b:v 20M -qp 0 -preset faster )

VVenC does not really support lossless encoding, so -qp 0, while being a valid parameter values, is not a good choice. I'd say with qp >= 15 you would start getting meaningful results. Below that we are currently looking into improving near-lossless quality.

b) i want to psnr the video encoded with my y4m but the result is (17.6...) not as i expecting it

Could you elaborate. This does not make much sense