--deadzone-inter --deadzone-intra 主要影响高频噪声，降低这两个值可
以某种程度上改善x264抹去细节的毛病
“deadzone controls the level of high prequency noise that is simply
dropped before encoding. High deadzone means you get rid of
expensive data to remove. Generally people modify the deadzone by
reducing it because they are aiming to increase grain retention.”
threads就是线程数，双核开3好像是最快
