The official documentation for x265 is very good, so this page will only cover recommended values and switches.
Source-independent settings
-
--preset veryslow
orslower
-
--no-rect
for slower computers. There's a slight chance it'll prove useful, but it probably isn't worth it. -
--no-amp
is similar torect
, although it seems to be slightly more useful. -
--no-open-gop
-
--no-cutree
since this seems to be a poor implementation ofmbtree
. -
--no-rskip
rskip
is a speed up that gives up some quality, so it's worth considering with bad CPUs. -
--ctu 64
-
--min-cu-size 8
-
--rdoq-level 2
-
--max-merge 5
-
--rc-lookahead 60
although it's irrelevant as long as it's larger than min-keyint -
--ref 6
for good CPUs, something like4
for worse ones. -
--bframes 16
or whatever your final bframes log output says. -
--rd 3
or4
(they're currently the same). If you can endure the slowdown, you can use6
, too, which allows you to test--rd-refine
. -
--subme 5
. You can also change this to7
, but this is known to sharpen. -
--merange 57
just don't go below32
and you should be fine. -
--high-tier
-
--range limited
-
--aud
-
--repeat-headers
Source-dependent settings
-
--output-depth 10
for 10-bit output. -
--input-depth 10
for 10-bit input. -
--colorprim 9
for HDR,1
for SDR. -
--colormatrix 9
for HDR,1
for SDR. -
--transfer 16
for HDR,1
for SDR. -
--hdr10
for HDR. -
--hdr10-opt
for 4:2:0 HDR,--no-hdr10-opt
for 4:4:4 HDR and SDR. -
--dhdr10-info /path/to/metadata.json
for HDR10+ content with metadata extracted using hdr10plus_parser.
-
--dolby-vision-profile 8.1
specified Dolby Vision profile. x265 can encode only to profiles5
,8.1
, and8.2
-
--dolby-vision-rpu /path/to/rpu.bin
for Dolby Vision metadata extracted using dovi_tool. -
--master-display "G(8500,39850)B(6550,2300)R(35400,14600)WP(15635,16450)L(10000000,20)"
for BT.2020 or
G(13250,34500)B(7500,3000)R(34000,16000)WP(15635,16450)L(10000000,1)
for Display P3 mastering display color primaries with the values for L coming from your source's MediaInfo for mastering display luminance.For example, if your source MediaInfo reads:
Mastering display color primaries : BT.2020 Mastering display luminance : min: 0.0000 cd/m2, max: 1000 cd/m2 Maximum Content Light Level : 711 cd/m2 Maximum Frame-Average Light Level : 617 cd/m2
This means you set
"G(8500,39850)B(6550,2300)R(35400,14600)WP(15635,16450)L(10000000,0)"
-
--max-cll "711,617"
from your source's MediaInfo for maximum content light level and maximum frame-average light level. The values here are from the above example. -
--cbqpoffs
and--crqpoffs
should usually be between -3 and 0 for 4:2:0. For 4:4:4, set this to something between 3 and 6. This sets an offset between the bitrate applied to the luma and the chroma planes. -
--qcomp
between0.60
and0.80
. -
--aq-mode 4
,3
,2
,1
, or--hevc-aq
with4
and3
usually being the two best options. If using aMod, there is an extra mode5
. These do the following:-
Standard adaptive quantization, simply add more bits to complex blocks.
-
Adaptive quantization with auto-variance.
-
Adaptive quantization with auto-variance and bias to dark scenes.
-
Adaptive quantization with auto-variance and better edge preservation.
-
Adaptive quantization with auto-variance, better edge preservation, and bias to dark scenes. Only in aMod.
-
hevc-aq
"scales the quantization step size according to the spatial activity of one coding unit relative to frame average spatial activity. This AQ method utilizes the minimum variance of sub-unit in each coding unit to represent the coding unit's spatial complexity." Like most of the x265 documentation, this sounds a lot fancier than it is. Don't enable with other modes turned on.
-
-
--aq-strength
between0.80
and1.40
for AQ modes 1-3 or0.50
and1.00
for AQ mode 4. -
--aq-bias-strength
between0.50
and1.20
if using aMod and an AQ mode with dark bias. This is a multiplier with lower numbers lowering the bias. Default is1.00
. -
--deblock -4:-4
to0:0
, similar to x264. Test at least -3:-3 to -1:-1 with live action, -2:-2 to 0:0 with animation. -
--ipratio
and--pbratio
same as x264 again. -
--psy-rd 0.80
to2.00
, similar-ish effect to x264. Values are generally higher than with x264, though. -
--psy-rdoq
anything from0.00
to2.00
usually. -
--no-sao
is usually best, but if your encode suffers from a lot of ringing, turn SAO back on. SAO does tend to blur quite heavily. -
--no-strong-intra-smoothing
on sharp/grainy content, you can leave this on for blurry content, as it's an additional blur that'll help prevent banding.