mencoder 1166685654_19.wmv -o test.flv -of lavf -oac mp3lame -lameopts abr:br=56 -srate 22050 -ovc lavc -lavcopts vcodec=flv:vbitrate=500:mbd=2:mv0:trell:v4mv:cbp:last_pred=3 -lavfopts  i_certify_that_my_video_stream_does_not_use_b_frames

 

Stupid video tricks with mplayer and mencoder

For people out there as lazy as I am (and by lazy, I mean "will spend four hours searching forums via google to find someone else who wanted to accomplish something tricky with one command line, and asked smarter people rather than dig through documentation to come up with the solution") I'm putting together a short list of simple but (imho) interesting things to do with mplayer and mencoder because I have had to do them at one point or another, and why should you suffer the pain of broken google links and forced forum registrations?
First, get mplayer. I'm not going into the esoterics of how to set it up for your system, I use windows and cygwin, and the latest windows binary with the all codecs package works for me.
And now, in no particular order...

• Converting a video file of arbitrary format to a sequence of images
  • Jpeg
    mplayer -nosound -vo jpeg inputfile
    
  • Png
    mplayer -nosound -vo png:z=n inputfile*where n is a number from 0-9 for compression quality (9 = best compression, but slowest)
    I always try and use png because they're usually better quality. If you're just grabbing stills for email or the web, use jpeg.
• Creating a flash video (.flv) file for web streaming
  • From a video source
    mencoder inputfile -ffourcc FLV1 -of lavf -ovc lavc -lavcopts vcodec=flv:acodec=mp3:abitrate=56 -srate 22050 -o outputfile
  • From a sequence of images
    mencoder mf://*.png -mf w=360:h=240:fps=12:type=png -of lavf -ffourcc FLV1 -ovc lavc -lavcopts vcodec=flv:acodec=mp3:abitrate=56 -srate 22050 -o outputfileObviously, replace the width, height, and frames per second above with the w/h/fps of your video. If you're using jpegs, use '*.jpeg' and 'type=jpeg' instead of png above. If you don't have any audio, use this:
    mencoder mf://*.png -mf w=360:h=240:fps=12:type=png -of lavf -ffourcc FLV1 -ovc lavc -lavcopts vcodec=flv -o outputfile
    
• Creating a flash player for your streaming .flv file
  • Jeroen's Free Flash Video Player
    I really shouldn't have to say anything else about this great offering, the documentation in the zip file and his web page tell you everything you need to know. Basically once you have a .flv file, you want to embed it in flash (.swf) or, better yet, stream it off a server to avoid the lengthy download. Most users out there are able to view flash, and developers who post video in other formats (asf, quicktime, or whatever) have problems with some percentage of browsers, depending on their audience. Using flash avoids this issue, and using flv lets you stream the video without the expense of a dedicated streaming server. But coding a player from scratch is a pain in the ass, and although I attempted a compile of Ming for windows to try and use Klaus's method I realized (again, being lazy) there was an even easier way. Steal Jeroen's terrific code, point it at your .flv and you're done! He even gives you the .fla file if you want to mess with the flash application and integrate it with your own. The controls and UI are clean, and it's free for non-commercial use (donation for commercial purposes).

 

• Official documentation:
• http://www1.mplayerhq.hu/MPlayer/DOCS/HTML/en/mencoder.html
  Note: The actual program man page differs from, and has additional information not included in, the
  online docs. It's a good idea to refer to the man page. You can find the mencoder one here:
  Mencoder man page
  This is a nice Wiki with some tips and help on Mencoder:
  http://en.gentoo-wiki.com/wiki/HOWTO_Mencoder_Introduction_Guide
  Critically, the docs include a magic incantation that seems to generate a working flash video file:

• mencoder \videos\soph1.wmv -o soph4.flv -of lavf -oac mp3lame -lameopts abr:br=56

  -ovc lavc -lavcopts vcodec=flv:vbitrate=500:mbd=2:mv0:trell:v4mv:cbp:last_pred=3 -srate 22050
• I'm still trying to work out what all these options do, but the output does seem to work.
  The 'srate' is the audio sampling rate. This is important because Flash video only supports these audio sampling rates:
• 11025
• 22050
• 44100

 

• Usage

• General format is:
• mencoder <input file> -o <output file> -ovc <video codec> [.. video options] -oac <audio codec> [..audio options] -of <output format coder> [...output format options..]
• The biggest trick I've noticed with mencoder is that you can defer down to libavcodec for everything, in which case the mencoder options take values which basically say: "just defer to libavcodec".
  Examples:
  -of lavf Use libavformat to determine output file format (otherwise you get avi by default)
  -oac lavc Use libavcodec to do the audio encoding
  -ovc lavc Activate libavcodec for video encoding
  "lavf" refers to audio/video file format (eg. .mov, .3gp, .avi., .mp4) as opposed to "lavc", which refers to codec.

 

• Options

• -vf Add a chain of video filters. These can include "scale" (see below) for scaling the image. Also "harddup" will generate "hard" duplicate frames. See audio sync below for why this is important.
• -oac Set the output audio codec
  values: copy, pcm, mp3lame (use Lame mp3 encoder), lavc (use libavcodec)
  Use '-nosound' to disable processing the audio stream.
• -of Set the output container format
  Use -of help to get a list of container formats
• −ovc Set the output video codec
  Use -ovc help to get the list of codecs. Use 'lavc' to defer down to the libavcodec library from ffmpeg. Then you need to specify the actual codec to use with the -lavcopts argument (see below).
  copy no encoding, just copy
  lavc use the libavcodec library (best quality says the app)
  vfw use the Video For Windows codecs. I haven't had much luck with this.
  What's tricky with mencoder is that you set the output codec, but then each
  codec takes its own set of options.
  You specify options to the codec with this syntax:
• -<name of codec>opts option1:option2=value:option3,...
• −lavcopts
• acodec=value I guess this overrides -oac and uses the libavcodec for audio encoding.
  Values include: mp2, mp3, ac3
• abitrate=<value>
• vcodec=<value>
  Check the manual. Flash (Sorenson) is "flv".
• mpeg1video
• mpeg2video
• msmpeg4v2
• mpeg4
• You can also specify format options. So to use libavcodec for generating the
  container format, use:
  -of lavf -lavfopts <...options>
  Where options include:
• format=mpg|asf|avi|swf|flv|mov|mp4
  Here is a complete example:
• mencoder /videos/dexp.mpg -o dell.avi -ovc lavc -oac lavc -lavcopts acodec=mp3:vcodec=msmpeg4v2 -of lavf -lavfopts format=avi
• This says:
• Input file is /videos/dexp.mpg
• Output file is dell.avi
• -ovc lavc : Use libavcodec as the video codec
• -oac lavc : Use libavcodec as the audio codec
• -lavcopts ... : Set the libavcodec options
• acodec=mp3 - Use mp3 for audio encoding
• vcodec=msmpeg4v2 - Use msmpeg4v2 codec for video encoding
• -of lavf : Use libavformat for building the output container
• -lavfopts format=avi : Use avi container format
• Setting output frame size
• Use:
• -vf scale=<width>:<height>
• like:
  -vf scale=320:240
  Add ",harddup" to force real copies of duplicate frames.
• Fixing Audio Sync Problems