how to differentiate .mp4 Audio file and .mp4 Video File In ASP.Net C#

Question

当我使用文件上传功能上传.mp4扩展名的音频和视频文件时，成功控制其上传，但在创建该文件的缩略图时很难区分是音频还是视频。

Answer 1

Try identifying MIME of file. In other words content-type:

string contentType = flFile.PostedFile.ContentType;
if("video/mp4" == contentType.ToLower()){
    //its video
}else if("audio/mp4" == contentType.ToLower()){
     //its audio
}