What is MEncoder?
Mencoder is a companion program to the MPlayer media player that can be used to encode or transform any audio or video stream that MPlayer can read. See the RestrictedFormats wiki page for instructions for enabling non-free formats in MPlayer and gmplayer. For more information visit the MPlayer web site.
Filters include cropping, scaling, vertical flipping, horizontal mirroring, expanding to create letterboxes, rotating, brightness/contrast, changing the aspect ratio of the video's pixels, colorspace conversion, hue/saturation, color-specific gamma correction, filters for reducing the visibiltiy of compression artifacts caused by MPEG compression (deblocking, deringing), automatic brightness/contrast enhancement (autolevel), sharpness/blur, denoising filters, and several different ways of deinterlacing. Certain filters capable of reversing telecine that do not work well with MPlayer can be used as well.
How To Use MEncoder
First, ensure that the mencoder package is installed with all appropriate dependencies. This does NOT work:
sudo apt-get install mencoder #obsolete
so you probably have to compile it from source or figure out what package has replaced it, if any. You may also consider finding and install the w32codecs package, if you will be working with proprietary formats, such as wmv.
To use mencoder, you must specify at least an input file, an output file, an audio encoder and a video encoder. As a general framework, you can use the following to convert a video from any type that mplayer can read, to an avi file using mp3 audio encoding.
mencoder <input_movie> -oac mp3lame -ovc lavc -o output_movie.avi
To see a list of audio encoders supported on your installation, run
mencoder -oac help
To use an audio encoder, specify it as in the example above with -oac <audio_encoder>.
Similarly for video encoders, search with
mencoder -ovc help