Swscale enabled ffmpeg breaks I422->* chroma conversions
If swscale is disabled in ffmpeg, we use the old img_convert functions which can for instance do I422->RV32 chroma conversions. With swscale enabled it uses the new conversions defined in ffmpeg/libswscale/* which unfortunately don't include I422. Thus video feeds like "http://lv.raad.tartu.ee:10201/mjpg/video.mjpg?resolution=320x240" don't work if the vout wants RV32 video (ie xvideo, x11, ...).