x265

> ffmpeg -i film.avi -c:v libx265 -crf 26 -preset fast -c:a aac -b:a 128k film.mp4

> ffmpeg -i film.avi -c:v libx265 -crf 25 -b:v 0 -preset medium -c:a libfdk_aac -afterburner 1 -b:a 140k -y film.mp4
> ffmpeg -i film.avi -c:v libx265 -crf 40 -b:v 0 -preset slow -c:a libfdk_aac -afterburner 1 -b:a 140k -y film.mp4

-preset

ultrafast
superfast
veryfast
faster
fast
medium (default)
slow
slower
veryslow
placebo

-tune

psnr 		disables adaptive quant, psy-rd, and cutree
ssim 		enables adaptive quant auto-mode, disables psy-rd
grain   	improves retention of film grain. more below
fastdecode 	no loop filters, no weighted pred, no intra in B
zerolatency 	no lookahead, no B frames, no cutree
animation 	improves encode quality for animated content

Kodier-Tests

Die bei libx265 voreingestellten Parameter lauten: -preset medium -crf 28.

Die Optionen -b:v 0 -crf 25 zusammen, sorgen für eine konstante Qualität.

3840x2160p@30FPS (8 Bit) / 226 Sekunden lang / TCL_Supercars_4K_Demo.mp4
Preset	weiter Optionen	erstellte Dateigröße in MiB	Kodierdauer in Sekunden
`-preset ultrafast`	`-b:v 0 -crf 25`	154	322
`-preset superfast`	`-b:v 0 -crf 25`	171	347
`-preset veryfast`	`-b:v 0 -crf 25`	204	566
`-preset faster`	`-b:v 0 -crf 25`	203	569
`-preset fast`	`-b:v 0 -crf 25`	210	758
`-preset medium`	`-b:v 0 -crf 25`	217	965
`-preset medium`	`-b:v 0 -crf 25 -tune psnr`	164	920
`-preset medium`	`-b:v 0 -crf 25 -tune ssim`	194	970
`-preset medium`	`-b:v 0 -crf 25 -tune grain`	387	1690
`-preset medium`	`-b:v 0 -crf 25 -tune zerolatency`	389	1008
`-preset medium`	`-b:v 0 -crf 25 -tune fastdecode`	220	967
`-preset slow`	`-b:v 0 -crf 25`	235	2384
`-preset slower`	`-b:v 0 -crf 25`	248	10425
`-preset veryslow`	`-b:v 0 -crf 25`	246	17722

3840x2160p@24FPS (10 Bit) / 126 Sekunden lang / Samsung_Extreme_Sports_UHD_4K_Demo.ts
Preset	weiter Optionen	erstellte Dateigröße in MiB	Kodierdauer in Sekunden
`-preset ultrafast`	`-b:v 0 -crf 25`	84	196
`-preset superfast`	`-b:v 0 -crf 25`	102	274
`-preset veryfast`	`-b:v 0 -crf 25`	117	397
`-preset faster`	`-b:v 0 -crf 25`	117	395
`-preset fast`	`-b:v 0 -crf 25`	118	508
`-preset mediaum`	`-b:v 0 -crf 25`	127	633
`-preset medium`	`-b:v 0 -crf 25 -tune psnr`	98	618
`-preset medium`	`-b:v 0 -crf 25 -tune ssim`	120	639
`-preset medium`	`-b:v 0 -crf 25 -tune grain`	174	921
`-preset medium`	`-b:v 0 -crf 25 -tune zerolatency`	?	?
`-preset medium`	`-b:v 0 -crf 25 -tune fastdecode`	?	?
`-preset slow`	`-b:v 0 -crf 25`	145	1765
`-preset slower`	`-b:v 0 -crf 25`	144	7199
`-preset veryslow`	`-b:v 0 -crf 25`	144	11648