the user may specify the integer ordinal of the value they desire. ie:
:option:`--log-level` 3 is equivalent to :option:`--log-level` debug.
-Standalone Executable Options
-=============================
+Executable Options
+==================
.. option:: --help, -h
**CLI ONLY**
+Logging/Statistic Options
+=========================
+
+.. option:: --log-level <integer|string>
+
+ Logging level. Debug level enables per-frame QP, metric, and bitrate
+ logging. If a CSV file is being generated, debug level makes the log
+ be per-frame rather than per-encode. Full level enables hash and
+ weight logging. -1 disables all logging, except certain fatal
+ errors, and can be specified by the string "none".
+
+ 0. error
+ 1. warning
+ 2. info **(default)**
+ 3. debug
+ 4. full
+
+.. option:: --no-progress
+
+ Disable periodic progress reports from the CLI
+
+ **CLI ONLY**
+
+.. option:: --csv <filename>
+
+ Writes encoding results to a comma separated value log file. Creates
+ the file if it doesnt already exist, else adds one line per run. if
+ :option:`--log-level` is debug or above, it writes one line per
+ frame. Default none
+
+.. option:: --cu-stats, --no-cu-stats
+
+ Records statistics on how each CU was coded (split depths and other
+ mode decisions) and reports those statistics at the end of the
+ encode. Default disabled
+
+.. option:: --ssim, --no-ssim
+
+ Calculate and report Structural Similarity values. It is
+ recommended to use :option:`--tune` ssim if you are measuring ssim,
+ else the results should not be used for comparison purposes.
+ Default disabled
+
+.. option:: --psnr, --no-psnr
+
+ Calculate and report Peak Signal to Noise Ratio. It is recommended
+ to use :option:`--tune` psnr if you are measuring PSNR, else the
+ results should not be used for comparison purposes. Default
+ disabled
+
+Performance Options
+===================
+
.. option:: --asm <integer:false:string>, --no-asm
x265 will use all detected CPU SIMD architectures by default. You can
One may also directly supply the CPU capability bitmap as an integer.
+.. option:: --frame-threads, -F <integer>
+
+ Number of concurrently encoded frames. Using a single frame thread
+ gives a slight improvement in compression, since the entire reference
+ frames are always available for motion compensation, but it has
+ severe performance implications. Default is an autodetected count
+ based on the number of CPU cores and whether WPP is enabled or not.
+
+ Over-allocation of frame threads will not improve performance, it
+ will generally just increase memory use.
+
.. option:: --threads <integer>
Number of threads to allocate for the worker thread pool This pool
is used for WPP and for distributed analysis and motion search:
:option:`--wpp` :option:`--pmode` and :option:`--pme` respectively.
- If :option:`--threads`=1 is specified, then no thread pool is
+ If :option:`--threads` 1 is specified, then no thread pool is
created. When no thread pool is created, all the thread pool
features are implicitly disabled. If all the pool features are
disabled by the user, then the pool is implicitly disabled.
Default 0, one thread is allocated per detected hardware thread
(logical CPU cores)
+.. option:: --wpp, --no-wpp
+
+ Enable Wavefront Parallel Processing. The encoder may begin encoding
+ a row as soon as the row above it is at least two CTUs ahead in the
+ encode process. This gives a 3-5x gain in parallelism for about 1%
+ overhead in compression efficiency.
+
+ This feature is implicitly disabled when no thread pool is present.
+
+ Default: Enabled
+
.. option:: --pmode, --no-pmode
Parallel mode decision, or distributed mode analysis. When enabled
the encoder will distribute the analysis work of each CU (merge,
inter, intra) across multiple worker threads. Only recommended if
x265 is not already saturating the CPU cores. In RD levels 3 and 4
- it will be most effective if --rect was enabled. At RD levels 5 and
+ it will be most effective if --rect is enabled. At RD levels 5 and
6 there is generally always enough work to distribute to warrant the
overhead, assuming your CPUs are not already saturated.
efficiency. In fact, since the modes are all measured in parallel it
makes certain early-outs impractical and thus you usually get
slightly better compression when it is enabled (at the expense of
- not skipping improbable modes).
+ not skipping improbable modes). This bypassing of early-outs can
+ cause pmode to slow down encodes, especially at faster presets.
This feature is implicitly disabled when no thread pool is present.
Sets parameters to preselected values, trading off compression efficiency against
encoding speed. These parameters are applied before all other input parameters are
- applied, and so you can override any parameters that these values control.
+ applied, and so you can override any parameters that these values control. See
+ :ref:`presets <presets>` for more detail.
0. ultrafast
1. superfast
.. option:: --tune, -t <string>
Tune the settings for a particular type of source or situation. The changes will
- be applied after :option:`--preset` but before all other parameters. Default none
-
- **Values:** psnr, ssim, zero-latency, fast-decode.
-
-.. option:: --frame-threads, -F <integer>
-
- Number of concurrently encoded frames. Using a single frame thread
- gives a slight improvement in compression, since the entire reference
- frames are always available for motion compensation, but it has
- severe performance implications. Default is an autodetected count
- based on the number of CPU cores and whether WPP is enabled or not.
-
- Over-allocation of frame threads will not improve performance, it
- will generally just increase memory use.
-
-.. option:: --log-level <integer|string>
-
- Logging level. Debug level enables per-frame QP, metric, and bitrate
- logging. If a CSV file is being generated, debug level makes the log
- be per-frame rather than per-encode. Full level enables hash and
- weight logging. -1 disables all logging, except certain fatal
- errors, and can be specified by the string "none".
-
- 0. error
- 1. warning
- 2. info **(default)**
- 3. debug
- 4. full
-
-.. option:: --csv <filename>
-
- Writes encoding results to a comma separated value log file. Creates
- the file if it doesnt already exist, else adds one line per run. if
- :option:`--log-level` is debug or above, it writes one line per
- frame. Default none
-
-.. option:: --cu-stats, --no-cu-stats
-
- Records statistics on how each CU was coded (split depths and other
- mode decisions) and reports those statistics at the end of the
- encode. Default disabled
-
-.. option:: --output, -o <filename>
-
- Bitstream output file name. If there are two extra CLI options, the
- first is implicitly the input filename and the second is the output
- filename, making the :option:`--output` option optional.
-
- The output file will always contain a raw HEVC bitstream, the CLI
- does not support any container file formats.
-
- **CLI ONLY**
-
-.. option:: --no-progress
+ be applied after :option:`--preset` but before all other parameters. Default none.
+ See :ref:`tunings <tunings>` for more detail.
- Disable CLI periodic progress reports
+ **Values:** psnr, ssim, grain, zero-latency, fast-decode, cbr.
- **CLI ONLY**
-
-Quality reporting metrics
+Input/Output File Options
=========================
-.. option:: --ssim, --no-ssim
-
- Calculate and report Structural Similarity values. It is
- recommended to use :option:`--tune` ssim if you are measuring ssim,
- else the results should not be used for comparison purposes.
- Default disabled
-
-.. option:: --psnr, --no-psnr
-
- Calculate and report Peak Signal to Noise Ratio. It is recommended
- to use :option:`--tune` psnr if you are measuring PSNR, else the
- results should not be used for comparison purposes. Default
- disabled
-
-Input Options
-=============
+These options all describe the input video sequence or, in the case of
+:option:`--dither`, operations that are performed on the sequence prior
+to encode. All options dealing with files (names, formats, offsets or
+frame counts) are only applicable to the CLI application.
.. option:: --input <filename>
**CLI ONLY**
-.. option:: --nr <integer>
-
- Noise reduction - an adaptive deadzone applied after DCT
- (subtracting from DCT coefficients), before quantization, on inter
- blocks. It does no pixel-level filtering, doesn't cross DCT block
- boundaries, has no overlap, doesn't affect intra blocks. The higher
- the strength value parameter, the more aggressively it will reduce
- noise.
-
- Enabling noise reduction will make outputs diverge between different
- numbers of frame threads. Outputs will be deterministic but the
- outputs of -F2 will no longer match the outputs of -F3, etc.
-
- **Values:** any value in range of 100 to 1000. Default disabled.
-
.. option:: --input-res <wxh>
YUV only: Source picture size [w x h]
.. option:: --interlaceMode <false|tff|bff>, --no-interlaceMode
- **EXPERIMENTAL** Specify interlace type of source pictures.
-
0. progressive pictures **(default)**
1. top field first
2. bottom field first
.. option:: --frames, -f <integer>
- Number of frames to be encoded. Default 0 (all)
+ Number of frames of input sequence to be encoded. Default 0 (all)
**CLI ONLY**
-.. option:: --qpfile <filename>
-
- Specify a text file which contains frametypes and QPs for some or
- all frames. The format of each line is:
-
- framenumber frametype QP
-
- Frametype can be one of [I,i,P,B,b]. **B** is a referenced B frame,
- **b** is an unreferenced B frame. **I** is a keyframe (random
- access point) while **i** is a I frame that is not a keyframe
- (references are not broken).
-
- Specifying QP (integer) is optional, and if specified they are
- clamped within the encoder to qpmin/qpmax.
-
-.. option:: --scaling-list <filename>
-
- Quantization scaling lists. HEVC supports 6 quantization scaling
- lists to be defined; one each for Y, Cb, Cr for intra prediction and
- one each for inter prediction.
-
- x265 does not use scaling lists by default, but this can also be
- made explicit by :option:`--scaling-list` *off*.
-
- HEVC specifies a default set of scaling lists which may be enabled
- without requiring them to be signaled in the SPS. Those scaling
- lists can be enabled via :option:`--scaling-list` *default*.
-
- All other strings indicate a filename containing custom scaling
- lists in the HM format. The encode will abort if the file is not
- parsed correctly. Custom lists must be signaled in the SPS
+.. option:: --output, -o <filename>
-.. option:: --lambda-file <filename>
+ Bitstream output file name. If there are two extra CLI options, the
+ first is implicitly the input filename and the second is the output
+ filename, making the :option:`--output` option optional.
- Specify a text file containing values for x265_lambda_tab and
- x265_lambda2_tab. Each table requires MAX_MAX_QP+1 (70) float
- values.
-
- The text file syntax is simple. Comma is considered to be
- white-space. All white-space is ignored. Lines must be less than 2k
- bytes in length. Content following hash (#) characters are ignored.
- The values read from the file are logged at :option:`--log-level`
- debug.
+ The output file will always contain a raw HEVC bitstream, the CLI
+ does not support any container file formats.
- Note that the lambda tables are process-global and so the new values
- affect all encoders running in the same process.
-
- Lambda values affect encoder mode decisions, the lower the lambda
- the more bits it will try to spend on signaling information (motion
- vectors and splits) and less on residual. This feature is intended
- for experimentation.
+ **CLI ONLY**
Profile, Level, Tier
====================
parameters to meet those requirements but it will never raise
them.
-Quad-Tree analysis
-==================
+Mode decision / Analysis
+========================
-.. option:: --wpp, --no-wpp
+.. option:: --rd <0..6>
- Enable Wavefront Parallel Processing. The encoder may begin encoding
- a row as soon as the row above it is at least two CTUs ahead in the
- encode process. This gives a 3-5x gain in parallelism for about 1%
- overhead in compression efficiency. Default: Enabled
+ Level of RDO in mode decision. The higher the value, the more
+ exhaustive the analysis and the more rate distortion optimization is
+ used. The lower the value the faster the encode, the higher the
+ value the smaller the bitstream (in general). Default 3
+
+ Note that this table aims for accuracy, but is not necessarily our
+ final target behavior for each mode.
+
+ +-------+---------------------------------------------------------------+
+ | Level | Description |
+ +=======+===============================================================+
+ | 0 | sa8d mode and split decisions, intra w/ source pixels |
+ +-------+---------------------------------------------------------------+
+ | 1 | recon generated (better intra), RDO merge/skip selection |
+ +-------+---------------------------------------------------------------+
+ | 2 | RDO splits and merge/skip selection |
+ +-------+---------------------------------------------------------------+
+ | 3 | RDO mode and split decisions, chroma residual used for sa8d |
+ +-------+---------------------------------------------------------------+
+ | 4 | Adds RDO Quant |
+ +-------+---------------------------------------------------------------+
+ | 5 | Adds RDO prediction decisions |
+ +-------+---------------------------------------------------------------+
+ | 6 | Currently same as 5 |
+ +-------+---------------------------------------------------------------+
+
+ **Range of values:** 0: least .. 6: full RDO analysis
+
+Options which affect the coding unit quad-tree, sometimes referred to as
+the prediction quad-tree.
.. option:: --ctu, -s <64|32|16>
and less frame parallelism as well. Because of this the faster
presets use a CU size of 32. Default: 64
+.. option:: --rect, --no-rect
+
+ Enable analysis of rectangular motion partitions Nx2N and 2NxN
+ (50/50 splits, two directions). Default disabled
+
+.. option:: --amp, --no-amp
+
+ Enable analysis of asymmetric motion partitions (75/25 splits, four
+ directions). At RD levels 0 through 4, AMP partitions are only
+ considered at CU sizes 32x32 and below. At RD levels 5 and 6, it
+ will only consider AMP partitions as merge candidates (no motion
+ search) at 64x64, and as merge or inter candidates below 64x64.
+
+ The AMP partitions which are searched are derived from the current
+ best inter partition. If Nx2N (vertical rectangular) is the best
+ current prediction, then left and right asymmetrical splits will be
+ evaluated. If 2NxN (horizontal rectangular) is the best current
+ prediction, then top and bottom asymmetrical splits will be
+ evaluated, If 2Nx2N is the best prediction, and the block is not a
+ merge/skip, then all four AMP partitions are evaluated.
+
+ This setting has no effect if rectangular partitions are disabled.
+ Default disabled
+
+.. option:: --early-skip, --no-early-skip
+
+ Measure full CU size (2Nx2N) merge candidates first; if no residual
+ is found the analysis is short circuited. Default disabled
+
+.. option:: --fast-cbf, --no-fast-cbf
+
+ Short circuit analysis if a prediction is found that does not set
+ the coded block flag (aka: no residual was encoded). It prevents
+ the encoder from perhaps finding other predictions that also have no
+ residual but require less signaling bits or have less distortion.
+ Only applicable for RD levels 5 and 6. Default disabled
+
+.. option:: --fast-intra, --no-fast-intra
+
+ Perform an initial scan of every fifth intra angular mode, then
+ check modes +/- 2 distance from the best mode, then +/- 1 distance
+ from the best mode, effectively performing a gradient descent. When
+ enabled 10 modes in total are checked. When disabled all 33 angular
+ modes are checked. Only applicable for :option:`--rd` levels 4 and
+ below (medium preset and faster).
+
+.. option:: --b-intra, --no-b-intra
+
+ Enables the evaluation of intra modes in B slices. Default disabled.
+
+.. option:: --cu-lossless, --no-cu-lossless
+
+ For each CU, evaluate lossless (transform and quant bypass) encode
+ of the best non-lossless mode option as a potential rate distortion
+ optimization. If the global option :option:`--lossless` has been
+ specified, all CUs will be encoded as lossless unconditionally
+ regardless of whether this option was enabled. Default disabled.
+
+ Only effective at RD levels 3 and above, which perform RDO mode
+ decisions.
+
+.. option:: --tskip, --no-tskip
+
+ Enable evaluation of transform skip (bypass DCT but still use
+ quantization) coding for 4x4 TU coded blocks.
+
+ Only effective at RD levels 3 and above, which perform RDO mode
+ decisions. Default disabled
+
+.. option:: --tskip-fast, --no-tskip-fast
+
+ Only evaluate transform skip for NxN intra predictions (4x4 blocks).
+ Only applicable if transform skip is enabled. For chroma, only
+ evaluate if luma used tskip. Inter block tskip analysis is
+ unmodified. Default disabled
+
+Analysis re-use options, to improve performance when encoding the same
+sequence multiple times (presumably at varying bitrates). The encoder
+will not reuse analysis if the resolution and slice type parameters do
+not match.
+
+.. option:: --analysis-mode <string|int>
+
+ Specify whether analysis information of each frame is output by encoder
+ or input for reuse. By reading the analysis data writen by an
+ earlier encode of the same sequence, substantial redundant work may
+ be avoided.
+
+ The following data may be stored and reused:
+ I frames - split decisions and luma intra directions of all CUs.
+ P/B frames - motion vectors are dumped at each depth for all CUs.
+
+ **Values:** off(0), save(1): dump analysis data, load(2): read analysis data
+
+.. option:: --analysis-file <filename>
+
+ Specify a filename for analysis data (see :option:`--analysis-mode`)
+ If no filename is specified, x265_analysis.dat is used.
+
+Options which affect the transform unit quad-tree, sometimes referred to
+as the residual quad-tree (RQT).
+
.. option:: --tu-intra-depth <1..4>
The transform unit (residual) quad-tree begins with the same depth
| 5 | 1 | 8 | 1 | 8 | true |
+----+------------+-----------+------------+-----------+-----------+
| 6 | 2 | 8 | 1 | 8 | true |
- +----+------------+-----------+------------+-----------+-----------+
- | 7 | 2 | 8 | 2 | 8 | true |
- +----+------------+-----------+------------+-----------+-----------+
-
-.. option:: --merange <integer>
-
- Motion search range. Default 57
-
- The default is derived from the default CTU size (64) minus the luma
- interpolation half-length (4) minus maximum subpel distance (2)
- minus one extra pixel just in case the hex search method is used. If
- the search range were any larger than this, another CTU row of
- latency would be required for reference frames.
-
- **Range of values:** an integer from 0 to 32768
-
-.. option:: --max-merge <1..5>
-
- Maximum number of neighbor (spatial and temporal) candidate blocks
- that the encoder may consider for merging motion predictions. If a
- merge candidate results in no residual, it is immediately selected
- as a "skip". Otherwise the merge candidates are tested as part of
- motion estimation when searching for the least cost inter option.
- The max candidate number is encoded in the SPS and determines the
- bit cost of signaling merge CUs. Default 2
-
-.. option:: --temporal-mvp, --no-temporal-mvp
-
- Enable temporal motion vector predictors in P and B slices.
- This enables the use of the motion vector from the collocated block
- in the previous frame to be used as a predictor. Default is enabled
-
-Spatial/intra options
-=====================
-
-.. option:: --rdpenalty <0..2>
-
- When set to 1, transform units of size 32x32 are given a 4x bit cost
- penalty compared to smaller transform units, in intra coded CUs in P
- or B slices.
-
- When set to 2, transform units of size 32x32 are not even attempted,
- unless otherwise required by the maximum recursion depth. For this
- option to be effective with 32x32 intra CUs,
- :option:`--tu-intra-depth` must be at least 2. For it to be
- effective with 64x64 intra CUs, :option:`--tu-intra-depth` must be
- at least 3.
-
- Note that in HEVC an intra transform unit (a block of the residual
- quad-tree) is also a prediction unit, meaning that the intra
- prediction signal is generated for each TU block, the residual
- subtracted and then coded. The coding unit simply provides the
- prediction modes that will be used when predicting all of the
- transform units within the CU. This means that when you prevent
- 32x32 intra transform units, you are preventing 32x32 intra
- predictions.
-
- Default 0, disabled.
-
- **Values:** 0:disabled 1:4x cost penalty 2:force splits
-
-.. option:: --b-intra, --no-b-intra
-
- Enables the evaluation of intra modes in B slices. Default disabled.
-
-.. option:: --tskip, --no-tskip
-
- Enable evaluation of transform skip (bypass DCT but still use
- quantization) coding for 4x4 TU coded blocks.
-
- Only effective at RD levels 3 and above, which perform RDO mode
- decisions. Default disabled
-
-.. option:: --tskip-fast, --no-tskip-fast
-
- Only evaluate transform skip for NxN intra predictions (4x4 blocks).
- Only applicable if transform skip is enabled. For chroma, only
- evaluate if luma used tskip. Inter block tskip analysis is
- unmodified. Default disabled
-
-.. option:: --strong-intra-smoothing, --no-strong-intra-smoothing
-
- Enable strong intra smoothing for 32x32 intra blocks. Default enabled
-
-.. option:: --constrained-intra, --no-constrained-intra
-
- Constrained intra prediction. When generating intra predictions for
- blocks in inter slices, only intra-coded reference pixels are used.
- Inter-coded reference pixels are replaced with intra-coded neighbor
- pixels or default values. The general idea is to block the
- propagation of reference errors that may have resulted from lossy
- signals. Default disabled
-
-Mode decision / Analysis
-========================
-
-.. option:: --rect, --no-rect
-
- Enable analysis of rectangular motion partitions Nx2N and 2NxN
- (50/50 splits, two directions). Default disabled
-
-.. option:: --amp, --no-amp
-
- Enable analysis of asymmetric motion partitions (75/25 splits, four
- directions). At RD levels 0 through 4, AMP partitions are only
- considered at CU sizes 32x32 and below. At RD levels 5 and 6, it
- will only consider AMP partitions as merge candidates (no motion
- search) at 64x64, and as merge or inter candidates below 64x64.
-
- The AMP partitions which are searched are derived from the current
- best inter partition. If Nx2N (vertical rectangular) is the best
- current prediction, then left and right asymmetrical splits will be
- evaluated. If 2NxN (horizontal rectangular) is the best current
- prediction, then top and bottom asymmetrical splits will be
- evaluated, If 2Nx2N is the best prediction, and the block is not a
- merge/skip, then all four AMP partitions are evaluated.
+ +----+------------+-----------+------------+-----------+-----------+
+ | 7 | 2 | 8 | 2 | 8 | true |
+ +----+------------+-----------+------------+-----------+-----------+
- This setting has no effect if rectangular partitions are disabled.
- Default disabled
+ At --subme values larger than 2, chroma residual cost is included
+ in all subpel refinement steps and chroma residual is included in
+ all motion estimation decisions (selecting the best reference
+ picture in each list, and chosing between merge, uni-directional
+ motion and bi-directional motion). The 'slow' preset is the first
+ preset to enable the use of chroma residual.
-.. option:: --early-skip, --no-early-skip
+.. option:: --merange <integer>
- Measure full CU size (2Nx2N) merge candidates first; if no residual
- is found the analysis is short circuited. Default disabled
+ Motion search range. Default 57
-.. option:: --fast-cbf, --no-fast-cbf
+ The default is derived from the default CTU size (64) minus the luma
+ interpolation half-length (4) minus maximum subpel distance (2)
+ minus one extra pixel just in case the hex search method is used. If
+ the search range were any larger than this, another CTU row of
+ latency would be required for reference frames.
- Short circuit analysis if a prediction is found that does not set
- the coded block flag (aka: no residual was encoded). It prevents
- the encoder from perhaps finding other predictions that also have no
- residual but require less signaling bits or have less distortion.
- Only applicable for RD levels 5 and 6. Default disabled
+ **Range of values:** an integer from 0 to 32768
-.. option:: --fast-intra, --no-fast-intra
+.. option:: --max-merge <1..5>
- Perform an initial scan of every fifth intra angular mode, then
- check modes +/- 2 distance from the best mode, then +/- 1 distance
- from the best mode, effectively performing a gradient descent. When
- enabled 10 modes in total are checked. When disabled all 33 angular
- modes are checked. Only applicable for :option:`--rd` levels 3 and
- below (medium preset and faster).
+ Maximum number of neighbor (spatial and temporal) candidate blocks
+ that the encoder may consider for merging motion predictions. If a
+ merge candidate results in no residual, it is immediately selected
+ as a "skip". Otherwise the merge candidates are tested as part of
+ motion estimation when searching for the least cost inter option.
+ The max candidate number is encoded in the SPS and determines the
+ bit cost of signaling merge CUs. Default 2
+
+.. option:: --temporal-mvp, --no-temporal-mvp
+
+ Enable temporal motion vector predictors in P and B slices.
+ This enables the use of the motion vector from the collocated block
+ in the previous frame to be used as a predictor. Default is enabled
.. option:: --weightp, -w, --no-weightp
Enable weighted prediction in B slices. Default disabled
-.. option:: --rd <0..6>
+Spatial/intra options
+=====================
- Level of RDO in mode decision. The higher the value, the more
- exhaustive the analysis and the more rate distortion optimization is
- used. The lower the value the faster the encode, the higher the
- value the smaller the bitstream (in general). Default 3
+.. option:: --strong-intra-smoothing, --no-strong-intra-smoothing
- Note that this table aims for accuracy, but is not necessarily our
- final target behavior for each mode.
+ Enable strong intra smoothing for 32x32 intra blocks. Default enabled
- +-------+---------------------------------------------------------------+
- | Level | Description |
- +=======+===============================================================+
- | 0 | sa8d mode and split decisions, intra w/ source pixels |
- +-------+---------------------------------------------------------------+
- | 1 | recon generated (better intra), RDO merge/skip selection |
- +-------+---------------------------------------------------------------+
- | 2 | RDO splits and merge/skip selection |
- +-------+---------------------------------------------------------------+
- | 3 | RDO mode and split decisions |
- +-------+---------------------------------------------------------------+
- | 4 | Adds RDO Quant |
- +-------+---------------------------------------------------------------+
- | 5 | Adds RDO prediction decisions |
- +-------+---------------------------------------------------------------+
- | 6 | Currently same as 5 |
- +-------+---------------------------------------------------------------+
+.. option:: --constrained-intra, --no-constrained-intra
- **Range of values:** 0: least .. 6: full RDO analysis
+ Constrained intra prediction. When generating intra predictions for
+ blocks in inter slices, only intra-coded reference pixels are used.
+ Inter-coded reference pixels are replaced with intra-coded neighbor
+ pixels or default values. The general idea is to block the
+ propagation of reference errors that may have resulted from lossy
+ signals. Default disabled
-.. option:: --cu-lossless, --no-cu-lossless
+.. option:: --rdpenalty <0..2>
- For each CU, evaluate lossless (transform and quant bypass) encode
- of the best non-lossless mode option as a potential rate distortion
- optimization. If the global option :option:`--lossless` has been
- specified, all CUs will be encoded as lossless unconditionally
- regardless of whether this option was enabled. Default disabled.
+ When set to 1, transform units of size 32x32 are given a 4x bit cost
+ penalty compared to smaller transform units, in intra coded CUs in P
+ or B slices.
- Only effective at RD levels 3 and above, which perform RDO mode
- decisions.
+ When set to 2, transform units of size 32x32 are not even attempted,
+ unless otherwise required by the maximum recursion depth. For this
+ option to be effective with 32x32 intra CUs,
+ :option:`--tu-intra-depth` must be at least 2. For it to be
+ effective with 64x64 intra CUs, :option:`--tu-intra-depth` must be
+ at least 3.
-.. option:: --signhide, --no-signhide
+ Note that in HEVC an intra transform unit (a block of the residual
+ quad-tree) is also a prediction unit, meaning that the intra
+ prediction signal is generated for each TU block, the residual
+ subtracted and then coded. The coding unit simply provides the
+ prediction modes that will be used when predicting all of the
+ transform units within the CU. This means that when you prevent
+ 32x32 intra transform units, you are preventing 32x32 intra
+ predictions.
+
+ Default 0, disabled.
+
+ **Values:** 0:disabled 1:4x cost penalty 2:force splits
- Hide sign bit of one coeff per TU (rdo). The last sign is implied.
- This requires analyzing all the coefficients to determine if a sign
- must be toggled, and then to determine which one can be toggled with
- the least amount of distortion. Default enabled
-
Psycho-visual options
=====================
force rate control to increase global QP. Finding the optimal
psycho-visual parameters for a given video requires experimentation. Our
recommended defaults (1.0 for both) are generally on the low end of the
-spectrum. And generally the lower the bitrate, the lower the optimal
-psycho-visual settings.
+spectrum.
+
+The lower the bitrate, the lower the optimal psycho-visual settings. If
+the bitrate is too low for the psycho-visual settings, you will begin to
+see temporal artifacts (motion judder). This is caused when the encoder
+is forced to code skip blocks (no residual) in areas of difficult motion
+because it is the best option psycho-visually (they have great amounts
+of energy and no residual cost). One can lower psy-rd settings when
+judder is happening, and allow the encoder to use some blur in these
+areas of high motion.
.. option:: --psy-rd <float>
.. option:: --crf-min <0..51.0>
Specify an lower limit to the rate factor which may be assigned to
- any given frame (ensuring a min QP). This is dangerous when CRF is
- used in combination with VBV as it may result in buffer underruns.
- Default disabled
+ any given frame (ensuring a min compression factor).
.. option:: --vbv-bufsize <integer>
between 0 and 1, or in kbits. In other words these two option pairs
are equivalent::
- :option:`--vbv-bufsize` 1000 :option:`--vbv-init` 900
- :option:`--vbv-bufsize` 1000 :option:`--vbv-init` 0.9
+ --vbv-bufsize 1000 --vbv-init 900
+ --vbv-bufsize 1000 --vbv-init 0.9
Default 0.9
**Range of values:** an integer from 0 to 51
-.. option:: --ipratio <float>
-
- QP ratio factor between I and P slices. This ratio is used in all of
- the rate control modes. Some :option:`--tune` options may change the
- default value. It is not typically manually specified. Default 1.4
-
-.. option:: --pbratio <float>
-
- QP ratio factor between P and B slices. This ratio is used in all of
- the rate control modes. Some :option:`--tune` options may change the
- default value. It is not typically manually specified. Default 1.3
-
.. option:: --lossless, --no-lossless
Enables true lossless coding by bypassing scaling, transform,
and not enough in flat areas.
0. disabled
- 1. AQ enabled
- 2. AQ enabled with auto-variance **(default)**
+ 1. AQ enabled **(default)**
+ 2. AQ enabled with auto-variance
.. option:: --aq-strength <float>
less bits. This tends to improve detail in the backgrounds of video
with less detail in areas of high motion. Default enabled
-.. option:: --cbqpoffs <integer>
-
- Offset of Cb chroma QP from the luma QP selected by rate control.
- This is a general way to spend more or less bits on the chroma
- channel. Default 0
-
- **Range of values:** -12 to 12
+.. option:: --nr-intra <integer>, --nr-inter <integer>
-.. option:: --crqpoffs <integer>
+ Noise reduction - an adaptive deadzone applied after DCT
+ (subtracting from DCT coefficients), before quantization. It does
+ no pixel-level filtering, doesn't cross DCT block boundaries, has no
+ overlap, The higher the strength value parameter, the more
+ aggressively it will reduce noise.
- Offset of Cr chroma QP from the luma QP selected by rate control.
- This is a general way to spend more or less bits on the chroma
- channel. Default 0
+ Enabling noise reduction will make outputs diverge between different
+ numbers of frame threads. Outputs will be deterministic but the
+ outputs of -F2 will no longer match the outputs of -F3, etc.
- **Range of values:** -12 to 12
+ **Values:** any value in range of 0 to 2000. Default 0 (disabled).
.. option:: --pass <integer>
- Enable multipass rate control mode. Input is encoded multiple times,
+ Enable multi-pass rate control mode. Input is encoded multiple times,
storing the encoded information of each pass in a stats file from which
the consecutive pass tunes the qp of each frame to improve the quality
of the output. Default disabled
**Range of values:** 1 to 3
+.. option:: --stats <filename>
+
+ Specify file name of of the multi-pass stats file. If unspecified
+ the encoder will use x265_2pass.log
+
.. option:: --slow-firstpass, --no-slow-firstpass
- Enable a slow and more detailed first pass encode in Multipass rate
+ Enable a slow and more detailed first pass encode in multi-pass rate
control mode. Speed of the first pass encode is slightly lesser and
quality midly improved when compared to the default settings in a
- multipass encode. Default disabled (turbo mode enabled)
+ multi-pass encode. Default disabled (turbo mode enabled)
When **turbo** first pass is not disabled, these options are
set on the first pass to improve performance:
* :option:`--subme` = MIN(2, :option:`--subme`)
* :option:`--rd` = MIN(2, :option:`--rd`)
-.. option:: --analysis-mode <string|int>
+.. option:: --cbqpoffs <integer>
- Specify whether analysis information of each frame is output by encoder
- or input for reuse. By reading the analysis data writen by an
- earlier encode of the same sequence, substantial redundant work may
- be avoided.
+ Offset of Cb chroma QP from the luma QP selected by rate control.
+ This is a general way to spend more or less bits on the chroma
+ channel. Default 0
- The following data may be stored and reused:
- I frames - split decisions and luma intra directions of all CUs.
- P/B frames - motion vectors are dumped at each depth for all CUs.
+ **Range of values:** -12 to 12
- **Values:** off(0), save(1): dump analysis data, load(2): read analysis data
+.. option:: --crqpoffs <integer>
-.. option:: --analysis-file <filename>
+ Offset of Cr chroma QP from the luma QP selected by rate control.
+ This is a general way to spend more or less bits on the chroma
+ channel. Default 0
- Specify a filename for analysis data (see :option:`--analysis-mode`)
- If no filename is specified, x265_analysis.dat is used.
+ **Range of values:** -12 to 12
+
+.. option:: --ipratio <float>
+
+ QP ratio factor between I and P slices. This ratio is used in all of
+ the rate control modes. Some :option:`--tune` options may change the
+ default value. It is not typically manually specified. Default 1.4
+
+.. option:: --pbratio <float>
+
+ QP ratio factor between P and B slices. This ratio is used in all of
+ the rate control modes. Some :option:`--tune` options may change the
+ default value. It is not typically manually specified. Default 1.3
+
+.. option:: --qcomp <float>
+
+ qComp sets the quantizer curve compression factor. It weights the
+ frame quantizer based on the complexity of residual (measured by
+ lookahead). Default value is 0.6. Increasing it to 1 will
+ effectively generate CQP
+
+.. option:: --qstep <integer>
+
+ The maximum single adjustment in QP allowed to rate control. Default
+ 4
+
+.. option:: --ratetol <float>
+
+ The degree of rate fluctuation that x265 tolerates. Rate tolerance
+ is used along with overflow (difference between actual and target
+ bitrate), to adjust qp. Default is 1.0
+
+.. option:: --qblur <float>
+
+ Temporally blur quants. Default 0.5
+
+.. option:: --cplxblur <float>
+
+ temporally blur complexity. default 20
+
+Quantization Options
+====================
+
+Note that rate-distortion optimized quantization (RDOQ) is enabled
+implicitly at :option:`--rd` 4, 5, and 6 and disabled implicitly at all
+other levels.
+
+.. option:: --signhide, --no-signhide
+
+ Hide sign bit of one coeff per TU (rdo). The last sign is implied.
+ This requires analyzing all the coefficients to determine if a sign
+ must be toggled, and then to determine which one can be toggled with
+ the least amount of distortion. Default enabled
+
+.. option:: --qpfile <filename>
+
+ Specify a text file which contains frametypes and QPs for some or
+ all frames. The format of each line is:
+
+ framenumber frametype QP
+
+ Frametype can be one of [I,i,P,B,b]. **B** is a referenced B frame,
+ **b** is an unreferenced B frame. **I** is a keyframe (random
+ access point) while **i** is a I frame that is not a keyframe
+ (references are not broken).
+
+ Specifying QP (integer) is optional, and if specified they are
+ clamped within the encoder to qpmin/qpmax.
+
+.. option:: --scaling-list <filename>
+
+ Quantization scaling lists. HEVC supports 6 quantization scaling
+ lists to be defined; one each for Y, Cb, Cr for intra prediction and
+ one each for inter prediction.
+
+ x265 does not use scaling lists by default, but this can also be
+ made explicit by :option:`--scaling-list` *off*.
+
+ HEVC specifies a default set of scaling lists which may be enabled
+ without requiring them to be signaled in the SPS. Those scaling
+ lists can be enabled via :option:`--scaling-list` *default*.
+
+ All other strings indicate a filename containing custom scaling
+ lists in the HM format. The encode will abort if the file is not
+ parsed correctly. Custom lists must be signaled in the SPS
+
+.. option:: --lambda-file <filename>
+
+ Specify a text file containing values for x265_lambda_tab and
+ x265_lambda2_tab. Each table requires MAX_MAX_QP+1 (70) float
+ values.
+
+ The text file syntax is simple. Comma is considered to be
+ white-space. All white-space is ignored. Lines must be less than 2k
+ bytes in length. Content following hash (#) characters are ignored.
+ The values read from the file are logged at :option:`--log-level`
+ debug.
+
+ Note that the lambda tables are process-global and so the new values
+ affect all encoders running in the same process.
+
+ Lambda values affect encoder mode decisions, the lower the lambda
+ the more bits it will try to spend on signaling information (motion
+ vectors and splits) and less on residual. This feature is intended
+ for experimentation.
Loop filters
============
-.. option:: --lft, --no-lft
+.. option:: --deblock=<int>:<int>, --no-deblock
+
+ Toggle deblocking loop filter, optionally specify deblocking
+ strength offsets.
+
+ <int>:<int> - parsed as tC offset and Beta offset
+ <int>,<int> - parsed as tC offset and Beta offset
+ <int> - both tC and Beta offsets assigned the same value
+
+ If unspecified, the offsets default to 0. The offsets must be in a
+ range of -6 (lowest strength) to 6 (highest strength).
+
+ To disable the deblocking filter entirely, use --no-deblock or
+ --deblock=false. Default enabled, with both offsets defaulting to 0
- Toggle deblocking loop filter, default enabled
+ If deblocking is disabled, or the offsets are non-zero, these
+ changes from the default configuration are signaled in the PPS.
.. option:: --sao, --no-sao
9. bt2020nc
10. bt2020c
-.. option:: --chromalocs <0..5>
+.. option:: --chromaloc <0..5>
Specify chroma sample location for 4:2:0 inputs. Consult the HEVC
specification for a description of these values. Default undefined
.. option:: --aud, --no-aud
Emit an access unit delimiter NAL at the start of each slice access
- unit. If option:`--repeat-headers` is not enabled (indicating the
+ unit. If :option:`--repeat-headers` is not enabled (indicating the
user will be writing headers manually at the start of the stream)
the very first AUD will be skipped since it cannot be placed at the
start of the access unit, where it belongs. Default disabled
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