[FFmpeg-user] Which parameter for WEBM VP8/Vorbis quality depending on resolution?

[Timm Ganske]

Using my smartphone I sometimes do videos. It is very convenient that they can be played directly in Firefox. Currently I am using ffmpeg2theora to create Theora videos, but I want to change to webm (VP8/vorbis) because it uses less space for same quality resp. better quality for same space. The videos are in different resolutions, and sometimes I crop them. I want to have the bitrate adopting to what is reasonable for the resolution. If I set a fixed bitrate let us say 800 kb/s, it is too much for low resolutions (some are below 320x240) and not enough for high resolutions (my S3 is capable of Full HD). But I want to convert them using a single command line for all of them.

Is there a parameter for ffmpeg which lets me choose -video-quality (low, reasonable, good, excellent) which depends on the resolution? If not, is it possible to support such an option in the future? Or do I need some script which analyzes the video and sets the bitrate accordingly?