/usr/share/avconv/libvpx-720p50_60.avpreset is in libav-tools 4:0.8.17-0ubuntu0.12.04.2.
This file is owned by root:root, with mode 0o644.
The actual contents of the file can be viewed below.
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 | g=120
lag-in-frames=25
deadline=good
cpu-used=0
profile=0
qmax=51
qmin=11
slices=4
b=2M
#ignored unless using -pass 2
maxrate=24M
minrate=100k
auto-alt-ref=1
arnr-maxframes=7
arnr-strength=5
arnr-type=centered
|