The default for frame_skip_threshold is 0, which thus disables the libvpx
frame dropping.
Originally committed as revision 23522 to svn://svn.ffmpeg.org/ffmpeg/trunk
This mode emits no keyframes at all, despite its name.
Patch by James Zern, jzern at google dot com
Originally committed as revision 23521 to svn://svn.ffmpeg.org/ffmpeg/trunk