Subtitle options:
-s size set frame size (WxH or abbreviation)
-sn disable subtitle
-scodec codec force subtitle codec ('copy' to copy stream)
-stag fourcc/tag force subtitle tag/fourcc
-fix_sub_duration fix subtitles duration
-canvas_size size set canvas size (WxH or abbreviation)
-spre preset set the subtitle options to the indicated preset
字幕选项:
-s尺寸集框架尺寸(WxH或缩写)
-禁用字幕
-scodec编解码器强制字幕编解码器(“复制”到复制流)
-stag fourcc/tag force副标题tag/fourcc
-固定字幕持续时间固定字幕持续时间
-画布大小设置画布大小(WxH或缩写)
-spre preset将字幕选项设置为指定的预设