文件？是软件吗？
avi->rmvb：brp, hpp, erp, rpp……都可以
rmvb->avi：vdm(avs开启real档), eo video
avi->mpeg：tmpgenc, eo video
mpeg->avi：vdm, eo video
rmvb->mpeg：tmpgenc(要装real alternative), eo video
mpeg->rmvb：brp, hpp, erp, rpp……都可以
剪切的话，avi和mpeg可以用vdm，rmvb用real media editor
