NAME¶

x256 - encoder for creating H.265/HEVC video streams

SYNOPSIS¶

x265 [options] infile [-o] outfile

DESCRIPTION¶

x256 is a commandline encoder for creating H.265/High Efficiency Video Coding (HEVC) video streams. infile can be a YUV or Y4M video stream. outfile will be used to store the raw HEVC bitstream.

Executable Options:¶

-h/--help

Show this help text and exit

Output Options:¶

-o/--output <filename>

Bitstream output file name

--log-level <string>

Logging level: none error warning info debug full. Default info

--no-progress

Disable CLI progress reports

--[no-]cu-stats

Enable logging stats about distribution of cu across all modes. Default disabled

--csv <filename>

Comma separated log file, log level >= 3 frame log, else one line per run

Input Options:¶

--input <filename>

Raw YUV or Y4M input file name. `-` for stdin

--y4m

Force parsing of input stream as YUV4MPEG2 regardless of file extension

--fps <float|rational>

Source frame rate (float or num/denom), auto-detected if Y4M

--input-res WxH

Source picture size [w x h], auto-detected if Y4M

--input-depth <integer>

Bit-depth of input file. Default 8

--input-csp <string>

Source color space: i420, i444 or i422, auto-detected if Y4M. Default: i420

-f/--frames <integer>

Maximum number of frames to encode. Default all

--seek <integer>

First frame to encode

--[no-]interlace <bff|tff>

Indicate input pictures are interlace fields in temporal order. Default progressive

--dither

Enable dither if downscaling to 8 bit pixels. Default disabled

Quality reporting metrics:¶

--[no-]ssim

Enable reporting SSIM metric scores. Default disabled

--[no-]psnr

Enable reporting PSNR metric scores. Default disabled

Profile, Level, Tier:¶

--profile <string>

Enforce an encode profile: main, main10, mainstillpicture

--level-idc <integer|float>

Force a minimum required decoder level (as '5.0' or '50')

--[no-]high-tier

If a decoder level is specified, this modifier selects High tier of that level

Threading, performance:¶

--threads <integer>

Number of threads for thread pool (0: detect CPU core count, default)

-F/--frame-threads <integer>

Number of concurrently encoded frames. 0: auto-determined by core count

--[no-]wpp

Enable Wavefront Parallel Processing. Default enabled

--[no-]pmode

Parallel mode analysis. Default disabled

--[no-]pme

Parallel motion estimation. Default disabled

--[no-]asm <bool|int|string>

Override CPU detection. Default: auto

Presets:¶

-p/--preset <string>

Trade off performance for compression efficiency. Default medium

ultrafast, superfast, veryfast, faster, fast, medium, slow, slower, veryslow, or placebo

-t/--tune <string>

Tune the settings for a particular type of source or situation:

psnr, ssim, zerolatency, or fastdecode

Quad-Tree size and depth:¶

-s/--ctu <64|32|16>

Maximum CU size (default: 64x64). Default 64

--tu-intra-depth <integer>

Max TU recursive depth for intra CUs. Default 1

--tu-inter-depth <integer>

Max TU recursive depth for inter CUs. Default 1

--[no-]rect

Enable rectangular motion partitions Nx2N and 2NxN. Default disabled

--[no-]amp

Enable asymmetric motion partitions, requires --rect. Default disabled

Analysis:¶

--rd <0..6>

Level of RD in mode decision 0:least....6:full RDO. Default 3

--psy-rd <0..2.0>

Strength of psycho-visual rate distortion optimization, 0 to disable. Default 0.000000

--psy-rdoq <0..50.0>

Strength of psycho-visual optimization in quantization, 0 to disable. Default 0.000000

--nr <integer>

An integer value in range of 100 to 1000, which denotes strength of noise reduction. Default disabled

--[no-]tskip-fast

Enable fast intra transform skipping. Default disabled

--[no-]early-skip

Enable early SKIP detection. Default disabled

--[no-]fast-cbf

Enable early outs based on whether residual is coded. Default disabled

Coding tools:¶

-w/--[no-]weightp

Enable weighted prediction in P slices. Default enabled

--[no-]weightb

Enable weighted prediction in B slices. Default disabled

--[no-]cu-lossless

Consider lossless mode in CU RDO decisions. Default disabled

--[no-]signhide

Hide sign bit of one coeff per TU (rdo). Default enabled

--[no-]tskip

Enable intra 4x4 transform skipping. Default disabled

Temporal / motion search options:¶

--me <string>

Motion search method dia hex umh star full. Default 1

-m/--subme <integer>

Amount of subpel refinement to perform (0:least .. 7:most). Default 2

--merange <integer>

Motion search range. Default 57

--max-merge <1..5>

Maximum number of merge candidates. Default 2

--[no-]temporal-mvp

Enable temporal MV predictors. Default enabled

Spatial / intra options:¶

--[no-]constrained-intra

Constrained intra prediction (use only intra coded reference pixels) Default disabled

--[no-]b-intra

Enable intra in B frames in veryslow presets. Default disabled

--[no-]fast-intra

Enable faster search method for angular intra predictions. Default disabled

--rdpenalty <0..2>

penalty for 32x32 intra TU in non-I slices. 0:disabled 1:RD-penalty 2:maximum. Default 0

Slice decision options:¶

--[no-]open-gop

Enable open-GOP, allows I slices to be non-IDR. Default enabled

-I/--keyint <integer>

Max IDR period in frames. -1 for infinite-gop. Default 250

-i/--min-keyint <integer>

Scenecuts closer together than this are coded as I, not IDR. Default: auto

--no-scenecut

Disable adaptive I-frame decision

--scenecut <integer>

How aggressively to insert extra I-frames. Default 40

--rc-lookahead <integer>

Number of frames for frame-type lookahead (determines encoder latency) Default 20

--bframes <integer>

Maximum number of consecutive b-frames (now it only enables B GOP structure) Default 4

--bframe-bias <integer>

Bias towards B frame decisions. Default 0

--b-adapt <0..2>

0 - none, 1 - fast, 2 - full (trellis) adaptive B frame scheduling. Default 2

--[no-]b-pyramid

Use B-frames as references. Default enabled

--ref <integer>

max number of L0 references to be allowed (1 .. 16) Default 3

--qpfile <string>

Force frametypes and QPs for some or all frames Format of each line: framenumber frametype QP QP is optional (none lets x265 choose). Frametypes: I,i,P,B,b. QPs are restricted by qpmin/qpmax.

Rate control, Quantization:¶

--bitrate <integer>

Target bitrate (kbps) for ABR (implied). Default 0

-q/--qp <integer>

QP for P slices in CQP mode (implied). --ipratio and --pbration determine other slice QPs

--crf <float>

Quality-based VBR (0-51). Default 28.000000

--[no-]lossless

Enable lossless: bypass transform, quant and loop filters globally. Default disabled

--crf-max <float>

With CRF+VBV, limit RF to this value. Default 0.000000 May cause VBV underflows!

--crf-min <float>

With CRF+VBV, limit RF to this value. Default 0.000000 this specifies a minimum rate factor value for encode!

--vbv-maxrate <integer>

Max local bitrate (kbit/s). Default 0

--vbv-bufsize <integer>

Set size of the VBV buffer (kbit). Default 0

--vbv-init <float>

Initial VBV buffer occupancy (fraction of bufsize or in kbits). Default 0.900000

--aq-mode <integer>

Mode for Adaptive Quantization - 0:none 1:uniform AQ 2:auto variance. Default 2

--aq-strength <float>

Reduces blocking and blurring in flat and textured areas.(0 to 3.0). Default 1.000000

--[no-]cutree

Enable cutree for Adaptive Quantization. Default enabled

--ipratio <float>

QP factor between I and P. Default 1.400000

--pbratio <float>

QP factor between P and B. Default 1.300000

--cbqpoffs <integer>

Chroma Cb QP Offset. Default 0

--crqpoffs <integer>

Chroma Cr QP Offset. Default 0

--stats

Filename for stats file in multipass pass rate control. Default x265_2pass.log

--pass

Multi pass rate control. 1: First pass, creates stats file 2: Last pass, does not overwrite stats file 3: Nth pass, overwrites stats file

--[no-]slow-firstpass

Enable a slow first pass in a multipass rate control mode. Default disabled

--analysis-mode <string|int>

save - Dump analysis info into file, load - Load analysis buffers from the file. Default 0

--analysis-file <filename>

Specify file name used for either dumping or reading analysis data.

--scaling-list <string>

Specify a file containing HM style quant scaling lists or 'default' or 'off'. Default: off

--lambda-file <string>

Specify a file containing replacement values for the lambda tables MAX_MAX_QP+1 floats for lambda table, then again for lambda2 table Blank lines and lines starting with hash(#) are ignored Comma is considered to be white-space

Loop filters (deblock and SAO):¶

--[no-]lft

Enable Deblocking Loop Filter. Default enabled

--[no-]sao

Enable Sample Adaptive Offset. Default enabled

--[no-]sao-non-deblock

Use non-deblocked pixels, else right/bottom boundary areas skipped. Default disabled

VUI options:¶

--sar <width:height|int>

Sample Aspect Ratio, the ratio of width to height of an individual pixel. Choose from 0=undef, 1=1:1("square"), 2=12:11, 3=10:11, 4=16:11, 5=40:33, 6=24:11, 7=20:11, 8=32:11, 9=80:33, 10=18:11, 11=15:11, 12=64:33, 13=160:99, 14=4:3, 15=3:2, 16=2:1 or custom ratio of <int:int>. Default 0

--crop-rect <string>

Add 'left,top,right,bottom' to the bitstream-level cropping rectangle

--overscan <string>

Specify whether it is appropriate for decoder to show cropped region: undef, show or crop. Default undef

--videoformat <string>

Specify video format from undef, component, pal, ntsc, secam, mac. Default undef

--range <string>

Specify black level and range of luma and chroma signals as full or limited Default limited

--colorprim <string>

Specify color primaries from undef, bt709, bt470m, bt470bg, smpte170m, smpte240m, film, bt2020. Default undef

--transfer <string>

Specify transfer characteristics from undef, bt709, bt470m, bt470bg, smpte170m, smpte240m, linear, log100, log316, iec61966-2-4, bt1361e, iec61966-2-1, bt2020-10, bt2020-12. Default undef

--colormatrix <string>

Specify color matrix setting from undef, bt709, fcc, bt470bg, smpte170m, smpte240m, GBR, YCgCo, bt2020nc, bt2020c. Default undef

--chromaloc <integer>

Specify chroma sample location (0 to 5). Default of 0

Bitstream options:¶

--[no-]info

Emit SEI identifying encoder and parameters. Default enabled

--[no-]aud

Emit access unit delimiters at the start of each access unit. Default disabled

--[no-]hrd

Enable HRD parameters signalling. Default disabled

--[no-]repeat-headers

Emit SPS and PPS headers at each keyframe. Default disabled

--hash <integer>

Decoded Picture Hash SEI 0: disabled, 1: MD5, 2: CRC, 3: Checksum. Default 0

Reconstructed video options (debugging):¶

-r/--recon <filename>

Reconstructed raw image YUV or Y4M output file name

--recon-depth <integer>

Bit-depth of reconstructed raw image file. Defaults to input bit depth, or 8 if Y4M

SEE ALSO¶

Full documentation may be found at http://x265.readthedocs.org/en/default/cli.html.