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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 | +--------------+-----------------------------------------------------+ |