doc/reST/presets.rst

   1 Preset Options
   2 --------------
   3
   4 Presets
   5 =======
   6
   7 .. _preset-tune-ref:
   8
   9 x265 has a number of predefined :option:`--preset` options that make
  10 trade-offs between encode speed (encoded frames per second) and
  11 compression efficiency (quality per bit in the bitstream).  The default
  12 preset is medium, it does a reasonably good job of finding the best
  13 possible quality without spending enormous CPU cycles looking for the
  14 absolute most efficient way to achieve that quality.  As you go higher
  15 than medium, the encoder takes shortcuts to improve performance at the
  16 expense of quality and compression efficiency.  As you go lower than
  17 medium, the encoder tries harder and harder to achieve the best quailty
  18 per bit compression ratio.
  19
  20 The presets adjust encoder parameters to affect these trade-offs.
  21
  22 +--------------+-----------+-----------+----------+--------+------+--------+------+--------+----------+---------+
  23 |              | ultrafast | superfast | veryfast | faster | fast | medium | slow | slower | veryslow | placebo |
  24 +==============+===========+===========+==========+========+======+========+======+========+==========+=========+
  25 | ctu          |   32      |    32     |   32     |  64    |  64  |   64   |  64  |  64    |   64     |   64    |
  26 +--------------+-----------+-----------+----------+--------+------+--------+------+--------+----------+---------+
  27 | bframes      |    4      |     4     |    4     |   4    |  4   |    4   |  4   |   8    |    8     |    8    |
  28 +--------------+-----------+-----------+----------+--------+------+--------+------+--------+----------+---------+
  29 | b-adapt      |    0      |     0     |    0     |   0    |  2   |    2   |  2   |   2    |    2     |    2    |
  30 +--------------+-----------+-----------+----------+--------+------+--------+------+--------+----------+---------+
  31 | rc-lookahead |   10      |    10     |   15     |  15    |  15  |   20   |  25  |   30   |   40     |   60    |
  32 +--------------+-----------+-----------+----------+--------+------+--------+------+--------+----------+---------+
  33 | scenecut     |    0      |    40     |   40     |  40    |  40  |   40   |  40  |   40   |   40     |   40    |
  34 +--------------+-----------+-----------+----------+--------+------+--------+------+--------+----------+---------+
  35 | refs         |    1      |     1     |    1     |   1    |  3   |    3   |  3   |   3    |    5     |    5    |
  36 +--------------+-----------+-----------+----------+--------+------+--------+------+--------+----------+---------+
  37 | me           |   dia     |   hex     |   hex    |  hex   | hex  |   hex  | star |  star  |   star   |   star  |
  38 +--------------+-----------+-----------+----------+--------+------+--------+------+--------+----------+---------+
  39 | merange      |   25      |    44     |   57     |  57    |  57  |   57   | 57   |  57    |   57     |   92    |
  40 +--------------+-----------+-----------+----------+--------+------+--------+------+--------+----------+---------+
  41 | subme        |    0      |     1     |    1     |   2    |  2   |    2   |  3   |   3    |    4     |    5    |
  42 +--------------+-----------+-----------+----------+--------+------+--------+------+--------+----------+---------+
  43 | rect         |    0      |     0     |    0     |   0    |  0   |    0   |  1   |   1    |    1     |    1    |
  44 +--------------+-----------+-----------+----------+--------+------+--------+------+--------+----------+---------+
  45 | amp          |    0      |     0     |    0     |   0    |  0   |    0   |  0   |   1    |    1     |    1    |
  46 +--------------+-----------+-----------+----------+--------+------+--------+------+--------+----------+---------+
  47 | max-merge    |    2      |     2     |    2     |   2    |  2   |    2   |  3   |   3    |    4     |    5    |
  48 +--------------+-----------+-----------+----------+--------+------+--------+------+--------+----------+---------+
  49 | early-skip   |    1      |     1     |    1     |   1    |  0   |    0   |  0   |   0    |    0     |    0    |
  50 +--------------+-----------+-----------+----------+--------+------+--------+------+--------+----------+---------+
  51 | fast-intra   |    1      |     1     |    1     |   1    |  1   |    0   |  0   |   0    |    0     |    0    |
  52 +--------------+-----------+-----------+----------+--------+------+--------+------+--------+----------+---------+
  53 | b-intra      |    0      |     0     |    0     |   0    |  0   |    0   |  0   |   1    |    1     |    1    |
  54 +--------------+-----------+-----------+----------+--------+------+--------+------+--------+----------+---------+
  55 | sao          |    0      |     0     |    1     |   1    |  1   |    1   |  1   |   1    |    1     |    1    |
  56 +--------------+-----------+-----------+----------+--------+------+--------+------+--------+----------+---------+
  57 | signhide     |    0      |     1     |    1     |   1    |  1   |    1   |  1   |   1    |    1     |    1    |
  58 +--------------+-----------+-----------+----------+--------+------+--------+------+--------+----------+---------+
  59 | weightp      |    0      |     0     |    1     |   1    |  1   |    1   |  1   |   1    |    1     |    1    |
  60 +--------------+-----------+-----------+----------+--------+------+--------+------+--------+----------+---------+
  61 | weightb      |    0      |     0     |    0     |   0    |  0   |    0   |  0   |   1    |    1     |    1    |
  62 +--------------+-----------+-----------+----------+--------+------+--------+------+--------+----------+---------+
  63 | aq-mode      |    0      |     0     |    2     |   2    |  2   |    2   |  2   |   2    |    2     |    2    |
  64 +--------------+-----------+-----------+----------+--------+------+--------+------+--------+----------+---------+
  65 | cuTree       |    0      |     0     |    0     |   0    |  1   |    1   |  1   |   1    |    1     |    1    |
  66 +--------------+-----------+-----------+----------+--------+------+--------+------+--------+----------+---------+
  67 | rdLevel      |    2      |     2     |    2     |   2    |  2   |    3   |  4   |   6    |    6     |    6    |
  68 +--------------+-----------+-----------+----------+--------+------+--------+------+--------+----------+---------+
  69 | lft          |    0      |     1     |    1     |   1    |  1   |    1   |  1   |   1    |    1     |    1    |
  70 +--------------+-----------+-----------+----------+--------+------+--------+------+--------+----------+---------+
  71 | tu-intra     |    1      |     1     |    1     |   1    |  1   |    1   |  1   |   2    |    3     |    4    |
  72 +--------------+-----------+-----------+----------+--------+------+--------+------+--------+----------+---------+
  73 | tu-inter     |    1      |     1     |    1     |   1    |  1   |    1   |  1   |   2    |    3     |    4    |
  74 +--------------+-----------+-----------+----------+--------+------+--------+------+--------+----------+---------+
  75
  76 Placebo mode enables transform-skip prediction evaluation.
  77
  78 Tuning
  79 ======
  80
  81 There are a few :option:`--tune` options available, which are applied
  82 after the preset.
  83
  84 .. Note::
  85
  86         The *psnr* and *ssim* tune options disable all optimizations that
  87         sacrafice metric scores for perceived visual quality (also known as
  88         psycho-visual optimizations). By default x265 always tunes for
  89         highest perceived visual quality but if one intends to measure an
  90         encode using PSNR or SSIM for the purpose of benchmarking, we highly
  91         recommend you configure x265 to tune for that particular metric.
  92
  93 +--------------+-----------------------------------------------------+
  94 | --tune       | effect                                              |
  95 +==============+=====================================================+
  96 | psnr         | disables adaptive quant, psy-rd, and cutree         |
  97 +--------------+-----------------------------------------------------+
  98 | ssim         | enables adaptive quant auto-mode, disables psy-rd   |
  99 +--------------+-----------------------------------------------------+
 100 | fastdecode   | no loop filters, no weighted pred, no intra in B    |
 101 +--------------+-----------------------------------------------------+
 102 | zerolatency  | no lookahead, no B frames, no cutree                |
 103 +--------------+-----------------------------------------------------+