Rick

在普通计算机上，MD5碰撞的时间也是很快的

Hi c1982: I found a project called [filetype](https://github.com/h2non/filetype) which **infer the binary file type based on the magic numbers signature** in [image.go](https://github.com/h2non/filetype/blob/master/matchers/image.go), there're many image type matcher, maybe we can...

remove ffmpeg absolute path

1

Hi slaveofcode: when we use `exec.Command("ffmpeg", "-i", "inputfile", "-vcodec", "copy", "-acodec", "copy", "outputfile")`, we don't need to specified the absolute path of ffmpeg, just use "ffmpeg", is works fine, in...