avconv version 9.18-6:9.18-0ubuntu0.14.04.1, Copyright (c) 2000-2014 the Libav developers
  built on Mar 16 2015 13:20:58 with gcc 4.8 (Ubuntu 4.8.2-19ubuntu1)
Hyper fast Audio and Video encoder
usage: avconv [options] [[infile options] -i infile]... {[outfile options] outfile}...

Getting help:
    -h      -- print basic options
    -h long -- print more options
    -h full -- print all options (including all format and codec specific options, very long)
    See man avconv for detailed description of the options.

Print help / information / capabilities:
-L                  show license
-h topic            show help
-? topic            show help
-help topic         show help
--help topic        show help
-version            show version
-formats            show available formats
-codecs             show available codecs
-decoders           show available decoders
-encoders           show available encoders
-bsfs               show available bit stream filters
-protocols          show available protocols
-filters            show available filters
-pix_fmts           show available pixel formats
-sample_fmts        show available audio sample formats

Global options (affect whole program instead of just one file:
-loglevel loglevel  set libav* logging level
-v loglevel         set libav* logging level
-y                  overwrite output files
-stats              print progress report during encoding
-vol volume         change audio volume (256=normal)

Per-file main options:
-f fmt              force format
-c codec            codec name
-codec codec        codec name
-pre preset         preset name
-map_metadata outfile[,metadata]:infile[,metadata]  set metadata information of outfile from infile
-t duration         record or transcode "duration" seconds of audio/video
-fs limit_size      set the limit file size in bytes
-ss time_off        set the start time offset
-metadata string=string  add metadata
-target type        specify target file type ("vcd", "svcd", "dvd", "dv", "dv50", "pal-vcd", "ntsc-svcd", ...)
-frames number      set the number of frames to record
-filter filter_list  set stream filterchain

Video options:
-vframes number     set the number of video frames to record
-r rate             set frame rate (Hz value, fraction or abbreviation)
-s size             set frame size (WxH or abbreviation)
-aspect aspect      set aspect ratio (4:3, 16:9 or 1.3333, 1.7777)
-vn                 disable video
-vcodec codec       force video codec ('copy' to copy stream)
-pass n             select the pass number (1 or 2)
-vf filter list     video filters

Audio options:
-aframes number     set the number of audio frames to record
-aq quality         set audio quality (codec-specific)
-ar rate            set audio sampling rate (in Hz)
-ac channels        set number of audio channels
-an                 disable audio
-acodec codec       force audio codec ('copy' to copy stream)
-vol volume         change audio volume (256=normal)
-af filter list     audio filters

Subtitle options:
-sn                 disable subtitle
-scodec codec       force subtitle codec ('copy' to copy stream)
-stag fourcc/tag    force subtitle tag/fourcc