| 1 | ********************* |
| 2 | Command Line Options |
| 3 | ********************* |
| 4 | |
| 5 | .. _string-options-ref: |
| 6 | |
| 7 | Note that unless an option is listed as **CLI ONLY** the option is also |
| 8 | supported by x265_param_parse(). The CLI uses getopt to parse the |
| 9 | command line options so the short or long versions may be used and the |
| 10 | long options may be truncated to the shortest unambiguous abbreviation. |
| 11 | Users of the API must pass x265_param_parse() the full option name. |
| 12 | |
| 13 | Preset and tune have special implications. The API user must call |
| 14 | x265_param_default_preset() with the preset and tune parameters they |
| 15 | wish to use, prior to calling x265_param_parse() to set any additional |
| 16 | fields. The CLI does this for the user implicitly, so all CLI options |
| 17 | are applied after the user's preset and tune choices, regardless of the |
| 18 | order of the arguments on the command line. |
| 19 | |
| 20 | If there is an extra command line argument (not an option or an option |
| 21 | value) the CLI will treat it as the input filename. This effectively |
| 22 | makes the :option:`--input` specifier optional for the input file. If |
| 23 | there are two extra arguments, the second is treated as the output |
| 24 | bitstream filename, making :option:`--output` also optional if the input |
| 25 | filename was implied. This makes :command:`x265 in.y4m out.hevc` a valid |
| 26 | command line. If there are more than two extra arguments, the CLI will |
| 27 | consider this an error and abort. |
| 28 | |
| 29 | Generally, when an option expects a string value from a list of strings |
| 30 | the user may specify the integer ordinal of the value they desire. ie: |
| 31 | :option:`--log-level` 3 is equivalent to :option:`--log-level` debug. |
| 32 | |
| 33 | Executable Options |
| 34 | ================== |
| 35 | |
| 36 | .. option:: --help, -h |
| 37 | |
| 38 | Display help text |
| 39 | |
| 40 | **CLI ONLY** |
| 41 | |
| 42 | .. option:: --version, -V |
| 43 | |
| 44 | Display version details |
| 45 | |
| 46 | **CLI ONLY** |
| 47 | |
| 48 | Logging/Statistic Options |
| 49 | ========================= |
| 50 | |
| 51 | .. option:: --log-level <integer|string> |
| 52 | |
| 53 | Logging level. Debug level enables per-frame QP, metric, and bitrate |
| 54 | logging. If a CSV file is being generated, debug level makes the log |
| 55 | be per-frame rather than per-encode. Full level enables hash and |
| 56 | weight logging. -1 disables all logging, except certain fatal |
| 57 | errors, and can be specified by the string "none". |
| 58 | |
| 59 | 0. error |
| 60 | 1. warning |
| 61 | 2. info **(default)** |
| 62 | 3. debug |
| 63 | 4. full |
| 64 | |
| 65 | .. option:: --no-progress |
| 66 | |
| 67 | Disable periodic progress reports from the CLI |
| 68 | |
| 69 | **CLI ONLY** |
| 70 | |
| 71 | .. option:: --csv <filename> |
| 72 | |
| 73 | Writes encoding results to a comma separated value log file. Creates |
| 74 | the file if it doesnt already exist, else adds one line per run. if |
| 75 | :option:`--log-level` is debug or above, it writes one line per |
| 76 | frame. Default none |
| 77 | |
| 78 | .. option:: --cu-stats, --no-cu-stats |
| 79 | |
| 80 | Records statistics on how each CU was coded (split depths and other |
| 81 | mode decisions) and reports those statistics at the end of the |
| 82 | encode. Default disabled |
| 83 | |
| 84 | .. option:: --ssim, --no-ssim |
| 85 | |
| 86 | Calculate and report Structural Similarity values. It is |
| 87 | recommended to use :option:`--tune` ssim if you are measuring ssim, |
| 88 | else the results should not be used for comparison purposes. |
| 89 | Default disabled |
| 90 | |
| 91 | .. option:: --psnr, --no-psnr |
| 92 | |
| 93 | Calculate and report Peak Signal to Noise Ratio. It is recommended |
| 94 | to use :option:`--tune` psnr if you are measuring PSNR, else the |
| 95 | results should not be used for comparison purposes. Default |
| 96 | disabled |
| 97 | |
| 98 | Performance Options |
| 99 | =================== |
| 100 | |
| 101 | .. option:: --asm <integer:false:string>, --no-asm |
| 102 | |
| 103 | x265 will use all detected CPU SIMD architectures by default. You can |
| 104 | disable all assembly by using :option:`--no-asm` or you can specify |
| 105 | a comma separated list of SIMD architectures to use, matching these |
| 106 | strings: MMX2, SSE, SSE2, SSE3, SSSE3, SSE4, SSE4.1, SSE4.2, AVX, XOP, FMA4, AVX2, FMA3 |
| 107 | |
| 108 | Some higher architectures imply lower ones being present, this is |
| 109 | handled implicitly. |
| 110 | |
| 111 | One may also directly supply the CPU capability bitmap as an integer. |
| 112 | |
| 113 | .. option:: --frame-threads, -F <integer> |
| 114 | |
| 115 | Number of concurrently encoded frames. Using a single frame thread |
| 116 | gives a slight improvement in compression, since the entire reference |
| 117 | frames are always available for motion compensation, but it has |
| 118 | severe performance implications. Default is an autodetected count |
| 119 | based on the number of CPU cores and whether WPP is enabled or not. |
| 120 | |
| 121 | Over-allocation of frame threads will not improve performance, it |
| 122 | will generally just increase memory use. |
| 123 | |
| 124 | .. option:: --threads <integer> |
| 125 | |
| 126 | Number of threads to allocate for the worker thread pool This pool |
| 127 | is used for WPP and for distributed analysis and motion search: |
| 128 | :option:`--wpp` :option:`--pmode` and :option:`--pme` respectively. |
| 129 | |
| 130 | If :option:`--threads` 1 is specified, then no thread pool is |
| 131 | created. When no thread pool is created, all the thread pool |
| 132 | features are implicitly disabled. If all the pool features are |
| 133 | disabled by the user, then the pool is implicitly disabled. |
| 134 | |
| 135 | Default 0, one thread is allocated per detected hardware thread |
| 136 | (logical CPU cores) |
| 137 | |
| 138 | .. option:: --wpp, --no-wpp |
| 139 | |
| 140 | Enable Wavefront Parallel Processing. The encoder may begin encoding |
| 141 | a row as soon as the row above it is at least two CTUs ahead in the |
| 142 | encode process. This gives a 3-5x gain in parallelism for about 1% |
| 143 | overhead in compression efficiency. |
| 144 | |
| 145 | This feature is implicitly disabled when no thread pool is present. |
| 146 | |
| 147 | Default: Enabled |
| 148 | |
| 149 | .. option:: --pmode, --no-pmode |
| 150 | |
| 151 | Parallel mode decision, or distributed mode analysis. When enabled |
| 152 | the encoder will distribute the analysis work of each CU (merge, |
| 153 | inter, intra) across multiple worker threads. Only recommended if |
| 154 | x265 is not already saturating the CPU cores. In RD levels 3 and 4 |
| 155 | it will be most effective if --rect is enabled. At RD levels 5 and |
| 156 | 6 there is generally always enough work to distribute to warrant the |
| 157 | overhead, assuming your CPUs are not already saturated. |
| 158 | |
| 159 | --pmode will increase utilization without reducing compression |
| 160 | efficiency. In fact, since the modes are all measured in parallel it |
| 161 | makes certain early-outs impractical and thus you usually get |
| 162 | slightly better compression when it is enabled (at the expense of |
| 163 | not skipping improbable modes). This bypassing of early-outs can |
| 164 | cause pmode to slow down encodes, especially at faster presets. |
| 165 | |
| 166 | This feature is implicitly disabled when no thread pool is present. |
| 167 | |
| 168 | Default disabled |
| 169 | |
| 170 | .. option:: --pme, --no-pme |
| 171 | |
| 172 | Parallel motion estimation. When enabled the encoder will distribute |
| 173 | motion estimation across multiple worker threads when more than two |
| 174 | references require motion searches for a given CU. Only recommended |
| 175 | if x265 is not already saturating CPU cores. :option:`--pmode` is |
| 176 | much more effective than this option, since the amount of work it |
| 177 | distributes is substantially higher. With --pme it is not unusual |
| 178 | for the overhead of distributing the work to outweigh the |
| 179 | parallelism benefits. |
| 180 | |
| 181 | This feature is implicitly disabled when no thread pool is present. |
| 182 | |
| 183 | --pme will increase utilization on many core systems with no effect |
| 184 | on the output bitstream. |
| 185 | |
| 186 | Default disabled |
| 187 | |
| 188 | .. option:: --preset, -p <integer|string> |
| 189 | |
| 190 | Sets parameters to preselected values, trading off compression efficiency against |
| 191 | encoding speed. These parameters are applied before all other input parameters are |
| 192 | applied, and so you can override any parameters that these values control. See |
| 193 | :ref:`presets <presets>` for more detail. |
| 194 | |
| 195 | 0. ultrafast |
| 196 | 1. superfast |
| 197 | 2. veryfast |
| 198 | 3. faster |
| 199 | 4. fast |
| 200 | 5. medium **(default)** |
| 201 | 6. slow |
| 202 | 7. slower |
| 203 | 8. veryslow |
| 204 | 9. placebo |
| 205 | |
| 206 | .. option:: --tune, -t <string> |
| 207 | |
| 208 | Tune the settings for a particular type of source or situation. The changes will |
| 209 | be applied after :option:`--preset` but before all other parameters. Default none. |
| 210 | See :ref:`tunings <tunings>` for more detail. |
| 211 | |
| 212 | **Values:** psnr, ssim, grain, zero-latency, fast-decode, cbr. |
| 213 | |
| 214 | Input/Output File Options |
| 215 | ========================= |
| 216 | |
| 217 | These options all describe the input video sequence or, in the case of |
| 218 | :option:`--dither`, operations that are performed on the sequence prior |
| 219 | to encode. All options dealing with files (names, formats, offsets or |
| 220 | frame counts) are only applicable to the CLI application. |
| 221 | |
| 222 | .. option:: --input <filename> |
| 223 | |
| 224 | Input filename, only raw YUV or Y4M supported. Use single dash for |
| 225 | stdin. This option name will be implied for the first "extra" |
| 226 | command line argument. |
| 227 | |
| 228 | **CLI ONLY** |
| 229 | |
| 230 | .. option:: --y4m |
| 231 | |
| 232 | Parse input stream as YUV4MPEG2 regardless of file extension, |
| 233 | primarily intended for use with stdin (ie: :option:`--input` - |
| 234 | :option:`--y4m`). This option is implied if the input filename has |
| 235 | a ".y4m" extension |
| 236 | |
| 237 | **CLI ONLY** |
| 238 | |
| 239 | .. option:: --input-depth <integer> |
| 240 | |
| 241 | YUV only: Bit-depth of input file or stream |
| 242 | |
| 243 | **Values:** any value between 8 and 16. Default is internal depth. |
| 244 | |
| 245 | **CLI ONLY** |
| 246 | |
| 247 | .. option:: --dither |
| 248 | |
| 249 | Enable high quality downscaling. Dithering is based on the diffusion |
| 250 | of errors from one row of pixels to the next row of pixels in a |
| 251 | picture. Only applicable when the input bit depth is larger than |
| 252 | 8bits and internal bit depth is 8bits. Default disabled |
| 253 | |
| 254 | **CLI ONLY** |
| 255 | |
| 256 | .. option:: --input-res <wxh> |
| 257 | |
| 258 | YUV only: Source picture size [w x h] |
| 259 | |
| 260 | **CLI ONLY** |
| 261 | |
| 262 | .. option:: --input-csp <integer|string> |
| 263 | |
| 264 | YUV only: Source color space. Only i420, i422, and i444 are |
| 265 | supported at this time. The internal color space is always the |
| 266 | same as the source color space (libx265 does not support any color |
| 267 | space conversions). |
| 268 | |
| 269 | 0. i400 |
| 270 | 1. i420 **(default)** |
| 271 | 2. i422 |
| 272 | 3. i444 |
| 273 | 4. nv12 |
| 274 | 5. nv16 |
| 275 | |
| 276 | .. option:: --fps <integer|float|numerator/denominator> |
| 277 | |
| 278 | YUV only: Source frame rate |
| 279 | |
| 280 | **Range of values:** positive int or float, or num/denom |
| 281 | |
| 282 | .. option:: --interlaceMode <false|tff|bff>, --no-interlaceMode |
| 283 | |
| 284 | 0. progressive pictures **(default)** |
| 285 | 1. top field first |
| 286 | 2. bottom field first |
| 287 | |
| 288 | HEVC encodes interlaced content as fields. Fields must be provided to |
| 289 | the encoder in the correct temporal order. The source dimensions |
| 290 | must be field dimensions and the FPS must be in units of fields per |
| 291 | second. The decoder must re-combine the fields in their correct |
| 292 | orientation for display. |
| 293 | |
| 294 | .. option:: --seek <integer> |
| 295 | |
| 296 | Number of frames to skip at start of input file. Default 0 |
| 297 | |
| 298 | **CLI ONLY** |
| 299 | |
| 300 | .. option:: --frames, -f <integer> |
| 301 | |
| 302 | Number of frames of input sequence to be encoded. Default 0 (all) |
| 303 | |
| 304 | **CLI ONLY** |
| 305 | |
| 306 | .. option:: --output, -o <filename> |
| 307 | |
| 308 | Bitstream output file name. If there are two extra CLI options, the |
| 309 | first is implicitly the input filename and the second is the output |
| 310 | filename, making the :option:`--output` option optional. |
| 311 | |
| 312 | The output file will always contain a raw HEVC bitstream, the CLI |
| 313 | does not support any container file formats. |
| 314 | |
| 315 | **CLI ONLY** |
| 316 | |
| 317 | Profile, Level, Tier |
| 318 | ==================== |
| 319 | |
| 320 | .. option:: --profile <string> |
| 321 | |
| 322 | Enforce the requirements of the specified profile, ensuring the |
| 323 | output stream will be decodable by a decoder which supports that |
| 324 | profile. May abort the encode if the specified profile is |
| 325 | impossible to be supported by the compile options chosen for the |
| 326 | encoder (a high bit depth encoder will be unable to output |
| 327 | bitstreams compliant with Main or Mainstillpicture). |
| 328 | |
| 329 | API users must use x265_param_apply_profile() after configuring |
| 330 | their param structure. Any changes made to the param structure after |
| 331 | this call might make the encode non-compliant. |
| 332 | |
| 333 | **Values:** main, main10, mainstillpicture, main422-8, main422-10, main444-8, main444-10 |
| 334 | |
| 335 | **CLI ONLY** |
| 336 | |
| 337 | .. option:: --level-idc <integer|float> |
| 338 | |
| 339 | Minimum decoder requirement level. Defaults to 0, which implies |
| 340 | auto-detection by the encoder. If specified, the encoder will |
| 341 | attempt to bring the encode specifications within that specified |
| 342 | level. If the encoder is unable to reach the level it issues a |
| 343 | warning and aborts the encode. If the requested requirement level is |
| 344 | higher than the actual level, the actual requirement level is |
| 345 | signaled. |
| 346 | |
| 347 | Beware, specifying a decoder level will force the encoder to enable |
| 348 | VBV for constant rate factor encodes, which may introduce |
| 349 | non-determinism. |
| 350 | |
| 351 | The value is specified as a float or as an integer with the level |
| 352 | times 10, for example level **5.1** is specified as "5.1" or "51", |
| 353 | and level **5.0** is specified as "5.0" or "50". |
| 354 | |
| 355 | Annex A levels: 1, 2, 2.1, 3, 3.1, 4, 4.1, 5, 5.1, 5.2, 6, 6.1, 6.2 |
| 356 | |
| 357 | .. option:: --high-tier, --no-high-tier |
| 358 | |
| 359 | If :option:`--level-idc` has been specified, the option adds the |
| 360 | intention to support the High tier of that level. If your specified |
| 361 | level does not support a High tier, a warning is issued and this |
| 362 | modifier flag is ignored. |
| 363 | |
| 364 | .. note:: |
| 365 | :option:`--profile`, :option:`--level-idc`, and |
| 366 | :option:`--high-tier` are only intended for use when you are |
| 367 | targeting a particular decoder (or decoders) with fixed resource |
| 368 | limitations and must constrain the bitstream within those limits. |
| 369 | Specifying a profile or level may lower the encode quality |
| 370 | parameters to meet those requirements but it will never raise |
| 371 | them. |
| 372 | |
| 373 | Mode decision / Analysis |
| 374 | ======================== |
| 375 | |
| 376 | .. option:: --rd <0..6> |
| 377 | |
| 378 | Level of RDO in mode decision. The higher the value, the more |
| 379 | exhaustive the analysis and the more rate distortion optimization is |
| 380 | used. The lower the value the faster the encode, the higher the |
| 381 | value the smaller the bitstream (in general). Default 3 |
| 382 | |
| 383 | Note that this table aims for accuracy, but is not necessarily our |
| 384 | final target behavior for each mode. |
| 385 | |
| 386 | +-------+---------------------------------------------------------------+ |
| 387 | | Level | Description | |
| 388 | +=======+===============================================================+ |
| 389 | | 0 | sa8d mode and split decisions, intra w/ source pixels | |
| 390 | +-------+---------------------------------------------------------------+ |
| 391 | | 1 | recon generated (better intra), RDO merge/skip selection | |
| 392 | +-------+---------------------------------------------------------------+ |
| 393 | | 2 | RDO splits and merge/skip selection | |
| 394 | +-------+---------------------------------------------------------------+ |
| 395 | | 3 | RDO mode and split decisions, chroma residual used for sa8d | |
| 396 | +-------+---------------------------------------------------------------+ |
| 397 | | 4 | Adds RDO Quant | |
| 398 | +-------+---------------------------------------------------------------+ |
| 399 | | 5 | Adds RDO prediction decisions | |
| 400 | +-------+---------------------------------------------------------------+ |
| 401 | | 6 | Currently same as 5 | |
| 402 | +-------+---------------------------------------------------------------+ |
| 403 | |
| 404 | **Range of values:** 0: least .. 6: full RDO analysis |
| 405 | |
| 406 | Options which affect the coding unit quad-tree, sometimes referred to as |
| 407 | the prediction quad-tree. |
| 408 | |
| 409 | .. option:: --ctu, -s <64|32|16> |
| 410 | |
| 411 | Maximum CU size (width and height). The larger the maximum CU size, |
| 412 | the more efficiently x265 can encode flat areas of the picture, |
| 413 | giving large reductions in bitrate. However this comes at a loss of |
| 414 | parallelism with fewer rows of CUs that can be encoded in parallel, |
| 415 | and less frame parallelism as well. Because of this the faster |
| 416 | presets use a CU size of 32. Default: 64 |
| 417 | |
| 418 | .. option:: --rect, --no-rect |
| 419 | |
| 420 | Enable analysis of rectangular motion partitions Nx2N and 2NxN |
| 421 | (50/50 splits, two directions). Default disabled |
| 422 | |
| 423 | .. option:: --amp, --no-amp |
| 424 | |
| 425 | Enable analysis of asymmetric motion partitions (75/25 splits, four |
| 426 | directions). At RD levels 0 through 4, AMP partitions are only |
| 427 | considered at CU sizes 32x32 and below. At RD levels 5 and 6, it |
| 428 | will only consider AMP partitions as merge candidates (no motion |
| 429 | search) at 64x64, and as merge or inter candidates below 64x64. |
| 430 | |
| 431 | The AMP partitions which are searched are derived from the current |
| 432 | best inter partition. If Nx2N (vertical rectangular) is the best |
| 433 | current prediction, then left and right asymmetrical splits will be |
| 434 | evaluated. If 2NxN (horizontal rectangular) is the best current |
| 435 | prediction, then top and bottom asymmetrical splits will be |
| 436 | evaluated, If 2Nx2N is the best prediction, and the block is not a |
| 437 | merge/skip, then all four AMP partitions are evaluated. |
| 438 | |
| 439 | This setting has no effect if rectangular partitions are disabled. |
| 440 | Default disabled |
| 441 | |
| 442 | .. option:: --early-skip, --no-early-skip |
| 443 | |
| 444 | Measure full CU size (2Nx2N) merge candidates first; if no residual |
| 445 | is found the analysis is short circuited. Default disabled |
| 446 | |
| 447 | .. option:: --fast-cbf, --no-fast-cbf |
| 448 | |
| 449 | Short circuit analysis if a prediction is found that does not set |
| 450 | the coded block flag (aka: no residual was encoded). It prevents |
| 451 | the encoder from perhaps finding other predictions that also have no |
| 452 | residual but require less signaling bits or have less distortion. |
| 453 | Only applicable for RD levels 5 and 6. Default disabled |
| 454 | |
| 455 | .. option:: --fast-intra, --no-fast-intra |
| 456 | |
| 457 | Perform an initial scan of every fifth intra angular mode, then |
| 458 | check modes +/- 2 distance from the best mode, then +/- 1 distance |
| 459 | from the best mode, effectively performing a gradient descent. When |
| 460 | enabled 10 modes in total are checked. When disabled all 33 angular |
| 461 | modes are checked. Only applicable for :option:`--rd` levels 4 and |
| 462 | below (medium preset and faster). |
| 463 | |
| 464 | .. option:: --b-intra, --no-b-intra |
| 465 | |
| 466 | Enables the evaluation of intra modes in B slices. Default disabled. |
| 467 | |
| 468 | .. option:: --cu-lossless, --no-cu-lossless |
| 469 | |
| 470 | For each CU, evaluate lossless (transform and quant bypass) encode |
| 471 | of the best non-lossless mode option as a potential rate distortion |
| 472 | optimization. If the global option :option:`--lossless` has been |
| 473 | specified, all CUs will be encoded as lossless unconditionally |
| 474 | regardless of whether this option was enabled. Default disabled. |
| 475 | |
| 476 | Only effective at RD levels 3 and above, which perform RDO mode |
| 477 | decisions. |
| 478 | |
| 479 | .. option:: --tskip, --no-tskip |
| 480 | |
| 481 | Enable evaluation of transform skip (bypass DCT but still use |
| 482 | quantization) coding for 4x4 TU coded blocks. |
| 483 | |
| 484 | Only effective at RD levels 3 and above, which perform RDO mode |
| 485 | decisions. Default disabled |
| 486 | |
| 487 | .. option:: --tskip-fast, --no-tskip-fast |
| 488 | |
| 489 | Only evaluate transform skip for NxN intra predictions (4x4 blocks). |
| 490 | Only applicable if transform skip is enabled. For chroma, only |
| 491 | evaluate if luma used tskip. Inter block tskip analysis is |
| 492 | unmodified. Default disabled |
| 493 | |
| 494 | Analysis re-use options, to improve performance when encoding the same |
| 495 | sequence multiple times (presumably at varying bitrates). The encoder |
| 496 | will not reuse analysis if the resolution and slice type parameters do |
| 497 | not match. |
| 498 | |
| 499 | .. option:: --analysis-mode <string|int> |
| 500 | |
| 501 | Specify whether analysis information of each frame is output by encoder |
| 502 | or input for reuse. By reading the analysis data writen by an |
| 503 | earlier encode of the same sequence, substantial redundant work may |
| 504 | be avoided. |
| 505 | |
| 506 | The following data may be stored and reused: |
| 507 | I frames - split decisions and luma intra directions of all CUs. |
| 508 | P/B frames - motion vectors are dumped at each depth for all CUs. |
| 509 | |
| 510 | **Values:** off(0), save(1): dump analysis data, load(2): read analysis data |
| 511 | |
| 512 | .. option:: --analysis-file <filename> |
| 513 | |
| 514 | Specify a filename for analysis data (see :option:`--analysis-mode`) |
| 515 | If no filename is specified, x265_analysis.dat is used. |
| 516 | |
| 517 | Options which affect the transform unit quad-tree, sometimes referred to |
| 518 | as the residual quad-tree (RQT). |
| 519 | |
| 520 | .. option:: --tu-intra-depth <1..4> |
| 521 | |
| 522 | The transform unit (residual) quad-tree begins with the same depth |
| 523 | as the coding unit quad-tree, but the encoder may decide to further |
| 524 | split the transform unit tree if it improves compression efficiency. |
| 525 | This setting limits the number of extra recursion depth which can be |
| 526 | attempted for intra coded units. Default: 1, which means the |
| 527 | residual quad-tree is always at the same depth as the coded unit |
| 528 | quad-tree |
| 529 | |
| 530 | Note that when the CU intra prediction is NxN (only possible with |
| 531 | 8x8 CUs), a TU split is implied, and thus the residual quad-tree |
| 532 | begins at 4x4 and cannot split any futhrer. |
| 533 | |
| 534 | .. option:: --tu-inter-depth <1..4> |
| 535 | |
| 536 | The transform unit (residual) quad-tree begins with the same depth |
| 537 | as the coding unit quad-tree, but the encoder may decide to further |
| 538 | split the transform unit tree if it improves compression efficiency. |
| 539 | This setting limits the number of extra recursion depth which can be |
| 540 | attempted for inter coded units. Default: 1. which means the |
| 541 | residual quad-tree is always at the same depth as the coded unit |
| 542 | quad-tree unless the CU was coded with rectangular or AMP |
| 543 | partitions, in which case a TU split is implied and thus the |
| 544 | residual quad-tree begins one layer below the CU quad-tree. |
| 545 | |
| 546 | Temporal / motion search options |
| 547 | ================================ |
| 548 | |
| 549 | .. option:: --me <integer|string> |
| 550 | |
| 551 | Motion search method. Generally, the higher the number the harder |
| 552 | the ME method will try to find an optimal match. Diamond search is |
| 553 | the simplest. Hexagon search is a little better. Uneven |
| 554 | Multi-Hexegon is an adaption of the search method used by x264 for |
| 555 | slower presets. Star is a three step search adapted from the HM |
| 556 | encoder: a star-pattern search followed by an optional radix scan |
| 557 | followed by an optional star-search refinement. Full is an |
| 558 | exhaustive search; an order of magnitude slower than all other |
| 559 | searches but not much better than umh or star. |
| 560 | |
| 561 | 0. dia |
| 562 | 1. hex **(default)** |
| 563 | 2. umh |
| 564 | 3. star |
| 565 | 4. full |
| 566 | |
| 567 | .. option:: --subme, -m <0..7> |
| 568 | |
| 569 | Amount of subpel refinement to perform. The higher the number the |
| 570 | more subpel iterations and steps are performed. Default 2 |
| 571 | |
| 572 | +----+------------+-----------+------------+-----------+-----------+ |
| 573 | | -m | HPEL iters | HPEL dirs | QPEL iters | QPEL dirs | HPEL SATD | |
| 574 | +====+============+===========+============+===========+===========+ |
| 575 | | 0 | 1 | 4 | 0 | 4 | false | |
| 576 | +----+------------+-----------+------------+-----------+-----------+ |
| 577 | | 1 | 1 | 4 | 1 | 4 | false | |
| 578 | +----+------------+-----------+------------+-----------+-----------+ |
| 579 | | 2 | 1 | 4 | 1 | 4 | true | |
| 580 | +----+------------+-----------+------------+-----------+-----------+ |
| 581 | | 3 | 2 | 4 | 1 | 4 | true | |
| 582 | +----+------------+-----------+------------+-----------+-----------+ |
| 583 | | 4 | 2 | 4 | 2 | 4 | true | |
| 584 | +----+------------+-----------+------------+-----------+-----------+ |
| 585 | | 5 | 1 | 8 | 1 | 8 | true | |
| 586 | +----+------------+-----------+------------+-----------+-----------+ |
| 587 | | 6 | 2 | 8 | 1 | 8 | true | |
| 588 | +----+------------+-----------+------------+-----------+-----------+ |
| 589 | | 7 | 2 | 8 | 2 | 8 | true | |
| 590 | +----+------------+-----------+------------+-----------+-----------+ |
| 591 | |
| 592 | At --subme values larger than 2, chroma residual cost is included |
| 593 | in all subpel refinement steps and chroma residual is included in |
| 594 | all motion estimation decisions (selecting the best reference |
| 595 | picture in each list, and chosing between merge, uni-directional |
| 596 | motion and bi-directional motion). The 'slow' preset is the first |
| 597 | preset to enable the use of chroma residual. |
| 598 | |
| 599 | .. option:: --merange <integer> |
| 600 | |
| 601 | Motion search range. Default 57 |
| 602 | |
| 603 | The default is derived from the default CTU size (64) minus the luma |
| 604 | interpolation half-length (4) minus maximum subpel distance (2) |
| 605 | minus one extra pixel just in case the hex search method is used. If |
| 606 | the search range were any larger than this, another CTU row of |
| 607 | latency would be required for reference frames. |
| 608 | |
| 609 | **Range of values:** an integer from 0 to 32768 |
| 610 | |
| 611 | .. option:: --max-merge <1..5> |
| 612 | |
| 613 | Maximum number of neighbor (spatial and temporal) candidate blocks |
| 614 | that the encoder may consider for merging motion predictions. If a |
| 615 | merge candidate results in no residual, it is immediately selected |
| 616 | as a "skip". Otherwise the merge candidates are tested as part of |
| 617 | motion estimation when searching for the least cost inter option. |
| 618 | The max candidate number is encoded in the SPS and determines the |
| 619 | bit cost of signaling merge CUs. Default 2 |
| 620 | |
| 621 | .. option:: --temporal-mvp, --no-temporal-mvp |
| 622 | |
| 623 | Enable temporal motion vector predictors in P and B slices. |
| 624 | This enables the use of the motion vector from the collocated block |
| 625 | in the previous frame to be used as a predictor. Default is enabled |
| 626 | |
| 627 | .. option:: --weightp, -w, --no-weightp |
| 628 | |
| 629 | Enable weighted prediction in P slices. This enables weighting |
| 630 | analysis in the lookahead, which influences slice decisions, and |
| 631 | enables weighting analysis in the main encoder which allows P |
| 632 | reference samples to have a weight function applied to them prior to |
| 633 | using them for motion compensation. In video which has lighting |
| 634 | changes, it can give a large improvement in compression efficiency. |
| 635 | Default is enabled |
| 636 | |
| 637 | .. option:: --weightb, --no-weightb |
| 638 | |
| 639 | Enable weighted prediction in B slices. Default disabled |
| 640 | |
| 641 | Spatial/intra options |
| 642 | ===================== |
| 643 | |
| 644 | .. option:: --strong-intra-smoothing, --no-strong-intra-smoothing |
| 645 | |
| 646 | Enable strong intra smoothing for 32x32 intra blocks. Default enabled |
| 647 | |
| 648 | .. option:: --constrained-intra, --no-constrained-intra |
| 649 | |
| 650 | Constrained intra prediction. When generating intra predictions for |
| 651 | blocks in inter slices, only intra-coded reference pixels are used. |
| 652 | Inter-coded reference pixels are replaced with intra-coded neighbor |
| 653 | pixels or default values. The general idea is to block the |
| 654 | propagation of reference errors that may have resulted from lossy |
| 655 | signals. Default disabled |
| 656 | |
| 657 | .. option:: --rdpenalty <0..2> |
| 658 | |
| 659 | When set to 1, transform units of size 32x32 are given a 4x bit cost |
| 660 | penalty compared to smaller transform units, in intra coded CUs in P |
| 661 | or B slices. |
| 662 | |
| 663 | When set to 2, transform units of size 32x32 are not even attempted, |
| 664 | unless otherwise required by the maximum recursion depth. For this |
| 665 | option to be effective with 32x32 intra CUs, |
| 666 | :option:`--tu-intra-depth` must be at least 2. For it to be |
| 667 | effective with 64x64 intra CUs, :option:`--tu-intra-depth` must be |
| 668 | at least 3. |
| 669 | |
| 670 | Note that in HEVC an intra transform unit (a block of the residual |
| 671 | quad-tree) is also a prediction unit, meaning that the intra |
| 672 | prediction signal is generated for each TU block, the residual |
| 673 | subtracted and then coded. The coding unit simply provides the |
| 674 | prediction modes that will be used when predicting all of the |
| 675 | transform units within the CU. This means that when you prevent |
| 676 | 32x32 intra transform units, you are preventing 32x32 intra |
| 677 | predictions. |
| 678 | |
| 679 | Default 0, disabled. |
| 680 | |
| 681 | **Values:** 0:disabled 1:4x cost penalty 2:force splits |
| 682 | |
| 683 | Psycho-visual options |
| 684 | ===================== |
| 685 | |
| 686 | Left to its own devices, the encoder will make mode decisions based on a |
| 687 | simple rate distortion formula, trading distortion for bitrate. This is |
| 688 | generally effective except for the manner in which this distortion is |
| 689 | measured. It tends to favor blurred reconstructed blocks over blocks |
| 690 | which have wrong motion. The human eye generally prefers the wrong |
| 691 | motion over the blur and thus x265 offers psycho-visual adjustments to |
| 692 | the rate distortion algorithm. |
| 693 | |
| 694 | :option:`--psy-rd` will add an extra cost to reconstructed blocks which |
| 695 | do not match the visual energy of the source block. The higher the |
| 696 | strength of :option:`--psy-rd` the more strongly it will favor similar |
| 697 | energy over blur and the more aggressively it will ignore rate |
| 698 | distortion. If it is too high, it will introduce visal artifacts and |
| 699 | increase bitrate enough for rate control to increase quantization |
| 700 | globally, reducing overall quality. psy-rd will tend to reduce the use |
| 701 | of blurred prediction modes, like DC and planar intra and bi-directional |
| 702 | inter prediction. |
| 703 | |
| 704 | :option:`--psy-rdoq` will adjust the distortion cost used in |
| 705 | rate-distortion optimized quantization (RDO quant), enabled in |
| 706 | :option:`--rd` 4 and above, favoring the preservation of energy in the |
| 707 | reconstructed image. :option:`--psy-rdoq` prevents RDOQ from blurring |
| 708 | all of the encoding options which psy-rd has to chose from. At low |
| 709 | strength levels, psy-rdoq will influence the quantization level |
| 710 | decisions, favoring higher AC energy in the reconstructed image. As |
| 711 | psy-rdoq strength is increased, more non-zero coefficient levels are |
| 712 | added and fewer coefficients are zeroed by RDOQ's rate distortion |
| 713 | analysis. High levels of psy-rdoq can double the bitrate which can have |
| 714 | a drastic effect on rate control, forcing higher overall QP, and can |
| 715 | cause ringing artifacts. psy-rdoq is less accurate than psy-rd, it is |
| 716 | biasing towards energy in general while psy-rd biases towards the energy |
| 717 | of the source image. But very large psy-rdoq values can sometimes be |
| 718 | beneficial, preserving film grain for instance. |
| 719 | |
| 720 | As a general rule, when both psycho-visual features are disabled, the |
| 721 | encoder will tend to blur blocks in areas of difficult motion. Turning |
| 722 | on small amounts of psy-rd and psy-rdoq will improve the perceived |
| 723 | visual quality. Increasing psycho-visual strength further will improve |
| 724 | quality and begin introducing artifacts and increase bitrate, which may |
| 725 | force rate control to increase global QP. Finding the optimal |
| 726 | psycho-visual parameters for a given video requires experimentation. Our |
| 727 | recommended defaults (1.0 for both) are generally on the low end of the |
| 728 | spectrum. |
| 729 | |
| 730 | The lower the bitrate, the lower the optimal psycho-visual settings. If |
| 731 | the bitrate is too low for the psycho-visual settings, you will begin to |
| 732 | see temporal artifacts (motion judder). This is caused when the encoder |
| 733 | is forced to code skip blocks (no residual) in areas of difficult motion |
| 734 | because it is the best option psycho-visually (they have great amounts |
| 735 | of energy and no residual cost). One can lower psy-rd settings when |
| 736 | judder is happening, and allow the encoder to use some blur in these |
| 737 | areas of high motion. |
| 738 | |
| 739 | .. option:: --psy-rd <float> |
| 740 | |
| 741 | Influence rate distortion optimizated mode decision to preserve the |
| 742 | energy of the source image in the encoded image at the expense of |
| 743 | compression efficiency. It only has effect on presets which use |
| 744 | RDO-based mode decisions (:option:`--rd` 3 and above). 1.0 is a |
| 745 | typical value. Default disabled. Experimental |
| 746 | |
| 747 | **Range of values:** 0 .. 2.0 |
| 748 | |
| 749 | .. option:: --psy-rdoq <float> |
| 750 | |
| 751 | Influence rate distortion optimized quantization by favoring higher |
| 752 | energy in the reconstructed image. This generally improves perceived |
| 753 | visual quality at the cost of lower quality metric scores. It only |
| 754 | has effect on slower presets which use RDO Quantization |
| 755 | (:option:`--rd` 4, 5 and 6). 1.0 is a typical value. Default |
| 756 | disabled. High values can be beneficial in preserving high-frequency |
| 757 | detail like film grain. Experimental |
| 758 | |
| 759 | **Range of values:** 0 .. 50.0 |
| 760 | |
| 761 | |
| 762 | Slice decision options |
| 763 | ====================== |
| 764 | |
| 765 | .. option:: --open-gop, --no-open-gop |
| 766 | |
| 767 | Enable open GOP, allow I-slices to be non-IDR. Default enabled |
| 768 | |
| 769 | .. option:: --keyint, -I <integer> |
| 770 | |
| 771 | Max intra period in frames. A special case of infinite-gop (single |
| 772 | keyframe at the beginning of the stream) can be triggered with |
| 773 | argument -1. Use 1 to force all-intra. Default 250 |
| 774 | |
| 775 | .. option:: --min-keyint, -i <integer> |
| 776 | |
| 777 | Minimum GOP size. Scenecuts closer together than this are coded as I |
| 778 | or P, not IDR. Minimum keyint is clamped to be at least half of |
| 779 | :option:`--keyint`. If you wish to force regular keyframe intervals |
| 780 | and disable adaptive I frame placement, you must use |
| 781 | :option:`--no-scenecut`. |
| 782 | |
| 783 | **Range of values:** >=0 (0: auto) |
| 784 | |
| 785 | .. option:: --scenecut <integer>, --no-scenecut |
| 786 | |
| 787 | How aggressively I-frames need to be inserted. The higher the |
| 788 | threshold value, the more aggressive the I-frame placement. |
| 789 | :option:`--scenecut` 0 or :option:`--no-scenecut` disables adaptive |
| 790 | I frame placement. Default 40 |
| 791 | |
| 792 | .. option:: --rc-lookahead <integer> |
| 793 | |
| 794 | Number of frames for slice-type decision lookahead (a key |
| 795 | determining factor for encoder latency). The longer the lookahead |
| 796 | buffer the more accurate scenecut decisions will be, and the more |
| 797 | effective cuTree will be at improving adaptive quant. Having a |
| 798 | lookahead larger than the max keyframe interval is not helpful. |
| 799 | Default 20 |
| 800 | |
| 801 | **Range of values:** Between the maximum consecutive bframe count (:option:`--bframes`) and 250 |
| 802 | |
| 803 | .. option:: --b-adapt <integer> |
| 804 | |
| 805 | Adaptive B frame scheduling. Default 2 |
| 806 | |
| 807 | **Values:** 0:none; 1:fast; 2:full(trellis) |
| 808 | |
| 809 | .. option:: --bframes, -b <0..16> |
| 810 | |
| 811 | Maximum number of consecutive b-frames. Use :option:`--bframes` 0 to |
| 812 | force all P/I low-latency encodes. Default 4. This parameter has a |
| 813 | quadratic effect on the amount of memory allocated and the amount of |
| 814 | work performed by the full trellis version of :option:`--b-adapt` |
| 815 | lookahead. |
| 816 | |
| 817 | .. option:: --bframe-bias <integer> |
| 818 | |
| 819 | Bias towards B frames in slicetype decision. The higher the bias the |
| 820 | more likely x265 is to use B frames. Can be any value between -90 |
| 821 | and 100 and is clipped to that range. Default 0 |
| 822 | |
| 823 | .. option:: --b-pyramid, --no-b-pyramid |
| 824 | |
| 825 | Use B-frames as references, when possible. Default enabled |
| 826 | |
| 827 | .. option:: --ref <1..16> |
| 828 | |
| 829 | Max number of L0 references to be allowed. This number has a linear |
| 830 | multiplier effect on the amount of work performed in motion search, |
| 831 | but will generally have a beneficial affect on compression and |
| 832 | distortion. Default 3 |
| 833 | |
| 834 | Quality, rate control and rate distortion options |
| 835 | ================================================= |
| 836 | |
| 837 | .. option:: --bitrate <integer> |
| 838 | |
| 839 | Enables single-pass ABR rate control. Specify the target bitrate in |
| 840 | kbps. Default is 0 (CRF) |
| 841 | |
| 842 | **Range of values:** An integer greater than 0 |
| 843 | |
| 844 | .. option:: --crf <0..51.0> |
| 845 | |
| 846 | Quality-controlled variable bitrate. CRF is the default rate control |
| 847 | method; it does not try to reach any particular bitrate target, |
| 848 | instead it tries to achieve a given uniform quality and the size of |
| 849 | the bitstream is determined by the complexity of the source video. |
| 850 | The higher the rate factor the higher the quantization and the lower |
| 851 | the quality. Default rate factor is 28.0. |
| 852 | |
| 853 | .. option:: --crf-max <0..51.0> |
| 854 | |
| 855 | Specify an upper limit to the rate factor which may be assigned to |
| 856 | any given frame (ensuring a max QP). This is dangerous when CRF is |
| 857 | used in combination with VBV as it may result in buffer underruns. |
| 858 | Default disabled |
| 859 | |
| 860 | .. option:: --crf-min <0..51.0> |
| 861 | |
| 862 | Specify an lower limit to the rate factor which may be assigned to |
| 863 | any given frame (ensuring a min compression factor). |
| 864 | |
| 865 | .. option:: --vbv-bufsize <integer> |
| 866 | |
| 867 | Specify the size of the VBV buffer (kbits). Enables VBV in ABR |
| 868 | mode. In CRF mode, :option:`--vbv-maxrate` must also be specified. |
| 869 | Default 0 (vbv disabled) |
| 870 | |
| 871 | .. option:: --vbv-maxrate <integer> |
| 872 | |
| 873 | Maximum local bitrate (kbits/sec). Will be used only if vbv-bufsize |
| 874 | is also non-zero. Both vbv-bufsize and vbv-maxrate are required to |
| 875 | enable VBV in CRF mode. Default 0 (disabled) |
| 876 | |
| 877 | .. option:: --vbv-init <float> |
| 878 | |
| 879 | Initial buffer occupancy. The portion of the decode buffer which |
| 880 | must be full before the decoder will begin decoding. Determines |
| 881 | absolute maximum frame size. May be specified as a fractional value |
| 882 | between 0 and 1, or in kbits. In other words these two option pairs |
| 883 | are equivalent:: |
| 884 | |
| 885 | --vbv-bufsize 1000 --vbv-init 900 |
| 886 | --vbv-bufsize 1000 --vbv-init 0.9 |
| 887 | |
| 888 | Default 0.9 |
| 889 | |
| 890 | **Range of values:** fractional: 0 - 1.0, or kbits: 2 .. bufsize |
| 891 | |
| 892 | .. option:: --qp, -q <integer> |
| 893 | |
| 894 | Specify base quantization parameter for Constant QP rate control. |
| 895 | Using this option enables Constant QP rate control. The specified QP |
| 896 | is assigned to P slices. I and B slices are given QPs relative to P |
| 897 | slices using param->rc.ipFactor and param->rc.pbFactor unless QP 0 |
| 898 | is specified, in which case QP 0 is used for all slice types. Note |
| 899 | that QP 0 does not cause lossless encoding, it only disables |
| 900 | quantization. Default disabled (CRF) |
| 901 | |
| 902 | **Range of values:** an integer from 0 to 51 |
| 903 | |
| 904 | .. option:: --lossless, --no-lossless |
| 905 | |
| 906 | Enables true lossless coding by bypassing scaling, transform, |
| 907 | quantization and in-loop filter processes. This is used for |
| 908 | ultra-high bitrates with zero loss of quality. Reconstructed output |
| 909 | pictures are bit-exact to the input pictures. Lossless encodes |
| 910 | implicitly have no rate control, all rate control options are |
| 911 | ignored. Slower presets will generally achieve better compression |
| 912 | efficiency (and generate smaller bitstreams). Default disabled. |
| 913 | |
| 914 | .. option:: --aq-mode <0|1|2> |
| 915 | |
| 916 | Adaptive Quantization operating mode. Raise or lower per-block |
| 917 | quantization based on complexity analysis of the source image. The |
| 918 | more complex the block, the more quantization is used. This offsets |
| 919 | the tendency of the encoder to spend too many bits on complex areas |
| 920 | and not enough in flat areas. |
| 921 | |
| 922 | 0. disabled |
| 923 | 1. AQ enabled **(default)** |
| 924 | 2. AQ enabled with auto-variance |
| 925 | |
| 926 | .. option:: --aq-strength <float> |
| 927 | |
| 928 | Adjust the strength of the adaptive quantization offsets. Setting |
| 929 | :option:`--aq-strength` to 0 disables AQ. Default 1.0. |
| 930 | |
| 931 | **Range of values:** 0.0 to 3.0 |
| 932 | |
| 933 | .. option:: --cutree, --no-cutree |
| 934 | |
| 935 | Enable the use of lookahead's lowres motion vector fields to |
| 936 | determine the amount of reuse of each block to tune adaptive |
| 937 | quantization factors. CU blocks which are heavily reused as motion |
| 938 | reference for later frames are given a lower QP (more bits) while CU |
| 939 | blocks which are quickly changed and are not referenced are given |
| 940 | less bits. This tends to improve detail in the backgrounds of video |
| 941 | with less detail in areas of high motion. Default enabled |
| 942 | |
| 943 | .. option:: --nr-intra <integer>, --nr-inter <integer> |
| 944 | |
| 945 | Noise reduction - an adaptive deadzone applied after DCT |
| 946 | (subtracting from DCT coefficients), before quantization. It does |
| 947 | no pixel-level filtering, doesn't cross DCT block boundaries, has no |
| 948 | overlap, The higher the strength value parameter, the more |
| 949 | aggressively it will reduce noise. |
| 950 | |
| 951 | Enabling noise reduction will make outputs diverge between different |
| 952 | numbers of frame threads. Outputs will be deterministic but the |
| 953 | outputs of -F2 will no longer match the outputs of -F3, etc. |
| 954 | |
| 955 | **Values:** any value in range of 0 to 2000. Default 0 (disabled). |
| 956 | |
| 957 | .. option:: --pass <integer> |
| 958 | |
| 959 | Enable multi-pass rate control mode. Input is encoded multiple times, |
| 960 | storing the encoded information of each pass in a stats file from which |
| 961 | the consecutive pass tunes the qp of each frame to improve the quality |
| 962 | of the output. Default disabled |
| 963 | |
| 964 | 1. First pass, creates stats file |
| 965 | 2. Last pass, does not overwrite stats file |
| 966 | 3. Nth pass, overwrites stats file |
| 967 | |
| 968 | **Range of values:** 1 to 3 |
| 969 | |
| 970 | .. option:: --stats <filename> |
| 971 | |
| 972 | Specify file name of of the multi-pass stats file. If unspecified |
| 973 | the encoder will use x265_2pass.log |
| 974 | |
| 975 | .. option:: --slow-firstpass, --no-slow-firstpass |
| 976 | |
| 977 | Enable a slow and more detailed first pass encode in multi-pass rate |
| 978 | control mode. Speed of the first pass encode is slightly lesser and |
| 979 | quality midly improved when compared to the default settings in a |
| 980 | multi-pass encode. Default disabled (turbo mode enabled) |
| 981 | |
| 982 | When **turbo** first pass is not disabled, these options are |
| 983 | set on the first pass to improve performance: |
| 984 | |
| 985 | * :option:`--fast-intra` |
| 986 | * :option:`--no-rect` |
| 987 | * :option:`--no-amp` |
| 988 | * :option:`--early-skip` |
| 989 | * :option:`--ref` = 1 |
| 990 | * :option:`--max-merge` = 1 |
| 991 | * :option:`--me` = DIA |
| 992 | * :option:`--subme` = MIN(2, :option:`--subme`) |
| 993 | * :option:`--rd` = MIN(2, :option:`--rd`) |
| 994 | |
| 995 | .. option:: --cbqpoffs <integer> |
| 996 | |
| 997 | Offset of Cb chroma QP from the luma QP selected by rate control. |
| 998 | This is a general way to spend more or less bits on the chroma |
| 999 | channel. Default 0 |
| 1000 | |
| 1001 | **Range of values:** -12 to 12 |
| 1002 | |
| 1003 | .. option:: --crqpoffs <integer> |
| 1004 | |
| 1005 | Offset of Cr chroma QP from the luma QP selected by rate control. |
| 1006 | This is a general way to spend more or less bits on the chroma |
| 1007 | channel. Default 0 |
| 1008 | |
| 1009 | **Range of values:** -12 to 12 |
| 1010 | |
| 1011 | .. option:: --ipratio <float> |
| 1012 | |
| 1013 | QP ratio factor between I and P slices. This ratio is used in all of |
| 1014 | the rate control modes. Some :option:`--tune` options may change the |
| 1015 | default value. It is not typically manually specified. Default 1.4 |
| 1016 | |
| 1017 | .. option:: --pbratio <float> |
| 1018 | |
| 1019 | QP ratio factor between P and B slices. This ratio is used in all of |
| 1020 | the rate control modes. Some :option:`--tune` options may change the |
| 1021 | default value. It is not typically manually specified. Default 1.3 |
| 1022 | |
| 1023 | .. option:: --qcomp <float> |
| 1024 | |
| 1025 | qComp sets the quantizer curve compression factor. It weights the |
| 1026 | frame quantizer based on the complexity of residual (measured by |
| 1027 | lookahead). Default value is 0.6. Increasing it to 1 will |
| 1028 | effectively generate CQP |
| 1029 | |
| 1030 | .. option:: --qstep <integer> |
| 1031 | |
| 1032 | The maximum single adjustment in QP allowed to rate control. Default |
| 1033 | 4 |
| 1034 | |
| 1035 | .. option:: --ratetol <float> |
| 1036 | |
| 1037 | The degree of rate fluctuation that x265 tolerates. Rate tolerance |
| 1038 | is used along with overflow (difference between actual and target |
| 1039 | bitrate), to adjust qp. Default is 1.0 |
| 1040 | |
| 1041 | .. option:: --qblur <float> |
| 1042 | |
| 1043 | Temporally blur quants. Default 0.5 |
| 1044 | |
| 1045 | .. option:: --cplxblur <float> |
| 1046 | |
| 1047 | temporally blur complexity. default 20 |
| 1048 | |
| 1049 | Quantization Options |
| 1050 | ==================== |
| 1051 | |
| 1052 | Note that rate-distortion optimized quantization (RDOQ) is enabled |
| 1053 | implicitly at :option:`--rd` 4, 5, and 6 and disabled implicitly at all |
| 1054 | other levels. |
| 1055 | |
| 1056 | .. option:: --signhide, --no-signhide |
| 1057 | |
| 1058 | Hide sign bit of one coeff per TU (rdo). The last sign is implied. |
| 1059 | This requires analyzing all the coefficients to determine if a sign |
| 1060 | must be toggled, and then to determine which one can be toggled with |
| 1061 | the least amount of distortion. Default enabled |
| 1062 | |
| 1063 | .. option:: --qpfile <filename> |
| 1064 | |
| 1065 | Specify a text file which contains frametypes and QPs for some or |
| 1066 | all frames. The format of each line is: |
| 1067 | |
| 1068 | framenumber frametype QP |
| 1069 | |
| 1070 | Frametype can be one of [I,i,P,B,b]. **B** is a referenced B frame, |
| 1071 | **b** is an unreferenced B frame. **I** is a keyframe (random |
| 1072 | access point) while **i** is a I frame that is not a keyframe |
| 1073 | (references are not broken). |
| 1074 | |
| 1075 | Specifying QP (integer) is optional, and if specified they are |
| 1076 | clamped within the encoder to qpmin/qpmax. |
| 1077 | |
| 1078 | .. option:: --scaling-list <filename> |
| 1079 | |
| 1080 | Quantization scaling lists. HEVC supports 6 quantization scaling |
| 1081 | lists to be defined; one each for Y, Cb, Cr for intra prediction and |
| 1082 | one each for inter prediction. |
| 1083 | |
| 1084 | x265 does not use scaling lists by default, but this can also be |
| 1085 | made explicit by :option:`--scaling-list` *off*. |
| 1086 | |
| 1087 | HEVC specifies a default set of scaling lists which may be enabled |
| 1088 | without requiring them to be signaled in the SPS. Those scaling |
| 1089 | lists can be enabled via :option:`--scaling-list` *default*. |
| 1090 | |
| 1091 | All other strings indicate a filename containing custom scaling |
| 1092 | lists in the HM format. The encode will abort if the file is not |
| 1093 | parsed correctly. Custom lists must be signaled in the SPS |
| 1094 | |
| 1095 | .. option:: --lambda-file <filename> |
| 1096 | |
| 1097 | Specify a text file containing values for x265_lambda_tab and |
| 1098 | x265_lambda2_tab. Each table requires MAX_MAX_QP+1 (70) float |
| 1099 | values. |
| 1100 | |
| 1101 | The text file syntax is simple. Comma is considered to be |
| 1102 | white-space. All white-space is ignored. Lines must be less than 2k |
| 1103 | bytes in length. Content following hash (#) characters are ignored. |
| 1104 | The values read from the file are logged at :option:`--log-level` |
| 1105 | debug. |
| 1106 | |
| 1107 | Note that the lambda tables are process-global and so the new values |
| 1108 | affect all encoders running in the same process. |
| 1109 | |
| 1110 | Lambda values affect encoder mode decisions, the lower the lambda |
| 1111 | the more bits it will try to spend on signaling information (motion |
| 1112 | vectors and splits) and less on residual. This feature is intended |
| 1113 | for experimentation. |
| 1114 | |
| 1115 | Loop filters |
| 1116 | ============ |
| 1117 | |
| 1118 | .. option:: --deblock=<int>:<int>, --no-deblock |
| 1119 | |
| 1120 | Toggle deblocking loop filter, optionally specify deblocking |
| 1121 | strength offsets. |
| 1122 | |
| 1123 | <int>:<int> - parsed as tC offset and Beta offset |
| 1124 | <int>,<int> - parsed as tC offset and Beta offset |
| 1125 | <int> - both tC and Beta offsets assigned the same value |
| 1126 | |
| 1127 | If unspecified, the offsets default to 0. The offsets must be in a |
| 1128 | range of -6 (lowest strength) to 6 (highest strength). |
| 1129 | |
| 1130 | To disable the deblocking filter entirely, use --no-deblock or |
| 1131 | --deblock=false. Default enabled, with both offsets defaulting to 0 |
| 1132 | |
| 1133 | If deblocking is disabled, or the offsets are non-zero, these |
| 1134 | changes from the default configuration are signaled in the PPS. |
| 1135 | |
| 1136 | .. option:: --sao, --no-sao |
| 1137 | |
| 1138 | Toggle Sample Adaptive Offset loop filter, default enabled |
| 1139 | |
| 1140 | .. option:: --sao-non-deblock, --no-sao-non-deblock |
| 1141 | |
| 1142 | Specify how to handle depencency between SAO and deblocking filter. |
| 1143 | When enabled, non-deblocked pixels are used for SAO analysis. When |
| 1144 | disabled, SAO analysis skips the right/bottom boundary areas. |
| 1145 | Default disabled |
| 1146 | |
| 1147 | VUI (Video Usability Information) options |
| 1148 | ========================================= |
| 1149 | |
| 1150 | x265 emits a VUI with only the timing info by default. If the SAR is |
| 1151 | specified (or read from a Y4M header) it is also included. All other |
| 1152 | VUI fields must be manually specified. |
| 1153 | |
| 1154 | .. option:: --sar <integer|w:h> |
| 1155 | |
| 1156 | Sample Aspect Ratio, the ratio of width to height of an individual |
| 1157 | sample (pixel). The user may supply the width and height explicitly |
| 1158 | or specify an integer from the predefined list of aspect ratios |
| 1159 | defined in the HEVC specification. Default undefined (not signaled) |
| 1160 | |
| 1161 | 1. 1:1 (square) |
| 1162 | 2. 12:11 |
| 1163 | 3. 10:11 |
| 1164 | 4. 16:11 |
| 1165 | 5. 40:33 |
| 1166 | 6. 24:11 |
| 1167 | 7. 20:11 |
| 1168 | 8. 32:11 |
| 1169 | 9. 80:33 |
| 1170 | 10. 18:11 |
| 1171 | 11. 15:11 |
| 1172 | 12. 64:33 |
| 1173 | 13. 160:99 |
| 1174 | 14. 4:3 |
| 1175 | 15. 3:2 |
| 1176 | 16. 2:1 |
| 1177 | |
| 1178 | .. option:: --crop-rect <left,top,right,bottom> |
| 1179 | |
| 1180 | Define the (overscan) region of the image that does not contain |
| 1181 | information because it was added to achieve certain resolution or |
| 1182 | aspect ratio. The decoder may be directed to crop away this region |
| 1183 | before displaying the images via the :option:`--overscan` option. |
| 1184 | Default undefined (not signaled) |
| 1185 | |
| 1186 | .. option:: --overscan <show|crop> |
| 1187 | |
| 1188 | Specify whether it is appropriate for the decoder to display or crop |
| 1189 | the overscan area. Default unspecified (not signaled) |
| 1190 | |
| 1191 | .. option:: --videoformat <integer|string> |
| 1192 | |
| 1193 | Specify the source format of the original analog video prior to |
| 1194 | digitizing and encoding. Default undefined (not signaled) |
| 1195 | |
| 1196 | 0. component |
| 1197 | 1. pal |
| 1198 | 2. ntsc |
| 1199 | 3. secam |
| 1200 | 4. mac |
| 1201 | 5. undefined |
| 1202 | |
| 1203 | .. option:: --range <full|limited> |
| 1204 | |
| 1205 | Specify output range of black level and range of luma and chroma |
| 1206 | signals. Default undefined (not signaled) |
| 1207 | |
| 1208 | .. option:: --colorprim <integer|string> |
| 1209 | |
| 1210 | Specify color primitive to use when converting to RGB. Default |
| 1211 | undefined (not signaled) |
| 1212 | |
| 1213 | 1. bt709 |
| 1214 | 2. undef |
| 1215 | 3. **reserved** |
| 1216 | 4. bt470m |
| 1217 | 5. bt470bg |
| 1218 | 6. smpte170m |
| 1219 | 7. smpte240m |
| 1220 | 8. film |
| 1221 | 9. bt2020 |
| 1222 | |
| 1223 | .. option:: --transfer <integer|string> |
| 1224 | |
| 1225 | Specify transfer characteristics. Default undefined (not signaled) |
| 1226 | |
| 1227 | 1. bt709 |
| 1228 | 2. undef |
| 1229 | 3. **reserved** |
| 1230 | 4. bt470m |
| 1231 | 5. bt470bg |
| 1232 | 6. smpte170m |
| 1233 | 7. smpte240m |
| 1234 | 8. linear |
| 1235 | 9. log100 |
| 1236 | 10. log316 |
| 1237 | 11. iec61966-2-4 |
| 1238 | 12. bt1361e |
| 1239 | 13. iec61966-2-1 |
| 1240 | 14. bt2020-10 |
| 1241 | 15. bt2020-12 |
| 1242 | |
| 1243 | .. option:: --colormatrix <integer|string> |
| 1244 | |
| 1245 | Specify color matrix setting i.e set the matrix coefficients used in |
| 1246 | deriving the luma and chroma. Default undefined (not signaled) |
| 1247 | |
| 1248 | 0. GBR |
| 1249 | 1. bt709 |
| 1250 | 2. undef |
| 1251 | 3. **reserved** |
| 1252 | 4. fcc |
| 1253 | 5. bt470bg |
| 1254 | 6. smpte170m |
| 1255 | 7. smpte240m |
| 1256 | 8. YCgCo |
| 1257 | 9. bt2020nc |
| 1258 | 10. bt2020c |
| 1259 | |
| 1260 | .. option:: --chromaloc <0..5> |
| 1261 | |
| 1262 | Specify chroma sample location for 4:2:0 inputs. Consult the HEVC |
| 1263 | specification for a description of these values. Default undefined |
| 1264 | (not signaled) |
| 1265 | |
| 1266 | Bitstream options |
| 1267 | ================= |
| 1268 | |
| 1269 | .. option:: --repeat-headers, --no-repeat-headers |
| 1270 | |
| 1271 | If enabled, x265 will emit VPS, SPS, and PPS headers with every |
| 1272 | keyframe. This is intended for use when you do not have a container |
| 1273 | to keep the stream headers for you and you want keyframes to be |
| 1274 | random access points. Default disabled |
| 1275 | |
| 1276 | .. option:: --info, --no-info |
| 1277 | |
| 1278 | Emit an informational SEI with the stream headers which describes |
| 1279 | the encoder version, build info, and encode parameters. This is very |
| 1280 | helpful for debugging purposes but encoding version numbers and |
| 1281 | build info could make your bitstreams diverge and interfere with |
| 1282 | regression testing. Default enabled |
| 1283 | |
| 1284 | .. option:: --hrd, --no-hrd |
| 1285 | |
| 1286 | Enable the signalling of HRD parameters to the decoder. The HRD |
| 1287 | parameters are carried by the Buffering Period SEI messages and |
| 1288 | Picture Timing SEI messages providing timing information to the |
| 1289 | decoder. Default disabled |
| 1290 | |
| 1291 | .. option:: --aud, --no-aud |
| 1292 | |
| 1293 | Emit an access unit delimiter NAL at the start of each slice access |
| 1294 | unit. If :option:`--repeat-headers` is not enabled (indicating the |
| 1295 | user will be writing headers manually at the start of the stream) |
| 1296 | the very first AUD will be skipped since it cannot be placed at the |
| 1297 | start of the access unit, where it belongs. Default disabled |
| 1298 | |
| 1299 | .. option:: --hash <integer> |
| 1300 | |
| 1301 | Emit decoded picture hash SEI, so the decoder may validate the |
| 1302 | reconstructed pictures and detect data loss. Also useful as a |
| 1303 | debug feature to validate the encoder state. Default None |
| 1304 | |
| 1305 | 1. MD5 |
| 1306 | 2. CRC |
| 1307 | 3. Checksum |
| 1308 | |
| 1309 | Debugging options |
| 1310 | ================= |
| 1311 | |
| 1312 | .. option:: --recon, -r <filename> |
| 1313 | |
| 1314 | Output file containing reconstructed images in display order. If the |
| 1315 | file extension is ".y4m" the file will contain a YUV4MPEG2 stream |
| 1316 | header and frame headers. Otherwise it will be a raw YUV file in the |
| 1317 | encoder's internal bit depth. |
| 1318 | |
| 1319 | **CLI ONLY** |
| 1320 | |
| 1321 | .. option:: --recon-depth <integer> |
| 1322 | |
| 1323 | Bit-depth of output file. This value defaults to the internal bit |
| 1324 | depth and currently cannot to be modified. |
| 1325 | |
| 1326 | **CLI ONLY** |
| 1327 | |
| 1328 | .. vim: noet |