NAME
       ffmpeg - FFmpeg video converter

SYNOPSIS
       ffmpeg [[infile options][-i infile]]... {[outfile options] outfile}...

DESCRIPTION
       If no input file is given, audio/video grabbing is done.

       As a general rule, options are applied to the next specified file. Therefore, order is important, and
       you can have the same option on the command line multiple times. Each occurrence is then applied to the
       next input or output file.

       * To set the video bitrate of the output file to 64kbit/s:

               ffmpeg -i input.avi -b 64k output.avi

       * To force the frame rate of the input and output file to 24 fps:

               ffmpeg -r 24 -i input.avi output.avi

       * To force the frame rate of the output file to 24 fps:

               ffmpeg -i input.avi -r 24 output.avi

       * To force the frame rate of input file to 1 fps and the output file to 24 fps:

               ffmpeg -r 1 -i input.avi -r 24 output.avi

       The format option may be needed for raw input files.

       By default, FFmpeg tries to convert as losslessly as possible: It uses the same audio and video parame-
       ters for the outputs as the one specified for the inputs.

http://bashconsole.org/man.1.ffmpeg