Make fake input/decoder smarter

[Idsa]

Is there any way to make fake input or decoder smarter? I'm writing fake input to file using mp4v encoder and it's size is too large. What I really need is just to record one picture (I even do not change it during recording). Ideally I want one frame to be recorded with some duration. Can I achieve it using VLC?

For now I see only one possibility to reduce file size - to play with mp4v encoder options. But what I have found looks more like workaround, not a pure solution.