title: Resize to a specific width and height using ffmpeg
body: <p>I need to generate thumbnails for videos, automatically. I cannot predict the format of the video, but I need the thumbnail to be 220x120 pixels, always. Using <code>-s 220x120</code> produces a weird stretch, just like <code>-vf "scale=220:120"</code>. I'd like the stretching to be uniform, either cutting away top and bottom if the video is too high or adding black borders.</p>