I have an upload function where you can upload file to a ContentFolder.

The code looks something like this:

var newFile = _contentRepository.GetDefault<GenericMedia>(dest.Directory.ContentLink);
var blob = _blobFactory.CreateBlob(newFile.BinaryDataContainer, Path.GetExtension(file.FileName));

using (Stream stream = blob.OpenWrite())
{
	file.InputStream.CopyTo(stream);
}

newFile.BinaryData = blob;
_contentRepository.Save(newFile, SaveAction.Publish);

GenericMedia is a base class for media files and then i have a few specialized media types (ImageFile, VideoFile etc) with extra properties.

Instead of always creating generic media i would like to create the correct media type based on the media descriptor attribute in my media types.

    [MediaDescriptor(ExtensionString = "jpg,jpeg,jpe,ico,gif,bmp,png")]
    public class ImageFile : GenericMedia, IContentImage
    {}

Does EPiServer have a function for retrieving the correct media type based on the file extention? Im guessiong something simular is done when uploading a file in edit mode.