我汗,知道2pass却不知道查一下two pass?
http://www.mplayerhq.hu/DOCS/HTML/en/menc-feat-x264.html
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14.5.1.3. Options pertaining to miscellaneous preferences
Two pass encoding: Above, it was suggested to always use two pass encoding, but there are still reasons for not using it. For instance, if you are capturing live TV and encoding in realtime, you are forced to use single-pass. Also, one pass is obviously faster than two passes; if you use the exact same set of options on both passes, two pass encoding is almost twice as slow.