Question

I have a C# application and I would like to be able to read in a WMV file and then write out a WMV file with reduced resolution/quality.

Are there any built-in libraries for C# that can do this? Do I need the Windows Media Format SDK?
Does anyone have experience with this?

Can I use something like FFmpeg for this?

Answer 1

You will have to decode and re-encode ( = transcode) the file to do this. By doing so you will inherently reduce quality since you are working off an already compressed base.

One way to do it if you need a high degree of control is is with a DirectShow wrapper for C#, i.e. DirectShow.NET. then you just need to define a simple transcoding graph.

Actually the simplest way to do this is with Expression Encoder (the successor to Windows Media Encoder) which has a simple managed API and should do the job with much less effort than integrating DirectShow.

There’s a summary article here. A simple transcoding job looks like this (sample from article, only presets changed):

      MediaItem src = new MediaItem
          (@"C:\WMdownloads\AdrenalineRush.wmv");
      Job job = new Job();
      job.MediaItems.Add(src);
      job.ApplyPreset(Presets.VC1WindowsMobile);
      job.OutputDirectory = @"C:\EncodedFiles";
      job.Encode();