Check if file is a media file in C#

Question

I need a method that could tell me if a file is image, audio or video file. Can I do this with C#?

Answer 1

It depends how robust you want it to be.

The simplest way to do it is to check the extension, like this:

static string[] mediaExtensions = {
    ".PNG", ".JPG", ".JPEG", ".BMP", ".GIF", //etc
    ".WAV", ".MID", ".MIDI", ".WMA", ".MP3", ".OGG", ".RMA", //etc
    ".AVI", ".MP4", ".DIVX", ".WMV", //etc
};

static bool IsMediaFile(string path) {
    return -1 != Array.IndexOf(mediaExtensions, Path.GetExtension(path).ToUpperInvariant());
}

EDIT: For those who really want LINQ, here it is:

return mediaExtensions.Contains(Path.GetExtension(path), StringComparer.OrdinalIgnoreCase);

Note that a file's extension is not a reliable indicator of its content; anyone can rename a file and change its extension.

If you don't have the extension, or if you don't trust it, you can read the beginning of the file and see if it matches file signatures for common media formats.

Answer 2

Method 1: Easiest - File name parsing. If the filename matches a known list of media file types (i.e. jpg gif wmv avi mp4 etc), then it matches a video, audio, or image file. This is not as robust since I can easily name a text file with the extension .avi or .jpg, but that does not necessarily make it a media file.

Method 2: Harder - Parse file header. For example, at CodeProject there is a C# RIFF Parser or this CodeProject article on Extracting IPTC header information from JPEG images

You'll end up ultimately having to use a combination of both methods. Most of what you are asking is already built into the .NET framework.

Answer 3

Yes you can but unless you are using a component to do it you'll need to write code to at least load the headers of those files in order to check if they are not corrupted. If the files are stored in a reliable way, you can maybe just check its file extension

foreach(string file in Directory.GetFiles("c:\\MyDir\\")
{
   if(file.EndsWith("jpg", false, null))
      //treat as image file
   else if(file.EndsWith("avi", false, null))
      //treats as avi video
   //and so on
}

Answer 4

This code verifies whether a file is a media file. mediaExtensions an array of well-known media filename extensions. The combination of path.Substring and path.IndexOf methods extract the file extension. Then the Array.IndexOf tells whether the extracted extension matches any elements of the mediaExtensions array. If not, Array.IndexOf returns -1 (not found), causing IsMediaFile to return false. Otherwise, Array.IndexOf returns the array index of the matching extesion, meaning a media file extension was found and IsMediaFile returns true.

Private Shared Function IsMediaFile(ByVal path As String) As Boolean
    Try
        Dim mediaExtensions As String() = {".PNG", ".JPG", ".JPEG", ".BMP", ".GIF", ".WAV", ".MID", ".MIDI", ".WMA", ".MP3", ".OGG", ".RMA", ".AVI", ".MP4", ".DIVX", ".WMV"}
        Return -1 <> Array.IndexOf(mediaExtensions, path.Substring(path.IndexOf("."), path.Length - path.IndexOf(".")).ToUpper)
    Catch ex As Exception
        Throw ex
    End Try
End Function

Answer 5

public static class CheckContentImage
{
    public const int ImageMinimumBytes = 512;

    public static bool IsImage(this IFormFile postedFile)
    {

        if (postedFile==null)
        {
            return false;
        }

        //-------------------------------------------
        //  Check the image mime types
        //-------------------------------------------
        if (postedFile.ContentType.ToLower() != "image/jpg" &&
                    postedFile.ContentType.ToLower() != "image/jpeg" &&
                    postedFile.ContentType.ToLower() != "image/pjpeg" &&
                    postedFile.ContentType.ToLower() != "image/gif" &&
                    postedFile.ContentType.ToLower() != "image/x-png" &&
                    postedFile.ContentType.ToLower() != "image/png")
        {
            return false;
        }

        //-------------------------------------------
        //  Check the image extension
        //-------------------------------------------
        if (Path.GetExtension(postedFile.FileName).ToLower() != ".jpg"
            && Path.GetExtension(postedFile.FileName).ToLower() != ".png"
            && Path.GetExtension(postedFile.FileName).ToLower() != ".gif"
            && Path.GetExtension(postedFile.FileName).ToLower() != ".jpeg")
        {
            return false;
        }

        //-------------------------------------------
        //  Attempt to read the file and check the first bytes
        //-------------------------------------------
        try
        {
            if (!postedFile.OpenReadStream().CanRead)
            {
                return false;
            }

            if (postedFile.Length < ImageMinimumBytes)
            {
                return false;
            }

            byte[] buffer = new byte[512];
            postedFile.OpenReadStream().Read(buffer, 0, 512);
            string content = System.Text.Encoding.UTF8.GetString(buffer);
            if (Regex.IsMatch(content, @"<script|<html|<head|<title|<body|<pre|<table|<a\s+href|<img|<plaintext|<cross\-domain\-policy",
                RegexOptions.IgnoreCase | RegexOptions.CultureInvariant | RegexOptions.Multiline))
            {
                return false;
            }
        }
        catch (Exception)
        {
            return false;
        }

        //-------------------------------------------
        //  Try to instantiate new Bitmap, if .NET will throw exception
        //  we can assume that it's not a valid image
        //-------------------------------------------

        try
        {
           
        }
        catch (Exception)
        {
            return false;
        }

        return true;
    }
}

Answer 6

You can always check for the file extension.