I would like to use video and audio presets of avconv (former ffmpeg). Which values are valid? I could find these presets in my system:

libvpx-1080p50_60
libvpx-1080p
libvpx-360p
libvpx-720p50_60
libvpx-720p
libx264-baseline
libx264-fast
libx264-faster
libx264-faster_firstpass
libx264-fast_firstpass
libx264-ipod320
libx264-ipod640
libx264-lossless_fast
libx264-lossless_max
libx264-lossless_medium
libx264-lossless_slow
libx264-lossless_slower
libx264-lossless_ultrafast
libx264-main
libx264-medium
libx264-medium_firstpass
libx264-placebo
libx264-placebo_firstpass
libx264-slow
libx264-slower
libx264-slower_firstpass
libx264-slow_firstpass
libx264-superfast
libx264-superfast_firstpass
libx264-ultrafast
libx264-ultrafast_firstpass
libx264-veryfast
libx264-veryfast_firstpass
libx264-veryslow
libx264-veryslow_firstpass

These are all video presets. How can I find out which audio presets I have installed?