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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 |