Multimedia documentation

Documents how to do some multimedia tasks

Convert wma to ogg

You need to dump the wma file into an uncompressed format (wav):

$ mplayer -ao pcm:file=/tmp/out.wav $wma_file

Then encode it into ogg:

$ oggenc -o ${wma_file%.wma}.ogg /tmp/out.wav

Convert ogg to mp3

Same as previous section for the dumping part, but use:

$ lame /tmp/out.wav ${ogg_file%.ogg}.mp3

for the encoding part.

Ripping a DVD

Download Handbrake (command line tool should be enough), and dvdbackup

Rip the dvd into a temporary directory (here the current directory):

dvdbackup -i /dev/dvd -o . -M

Then list the titles:

handbrake -i ~/tmp/where_was_ripped -t 0

Do the rip:

handbrake -i ~/tmp/where_was_ripped -t 1 -o $outfile.mkv  \
    --size 700 --two-pass --audio 1

Ripping an audio CD

There is a script called abcde that will do this very well. Download and install it and insert the CD you want to rip. The configuration is made using a configuration file: $HOME/.abcde.conf. Mine just contains:


Since I wanted to use FLAC instead of the default, Ogg Vorbis. The manpage documents all the configuration file options.

Once you are done configuring abcde, just cd to the directory where you want to rip and run:

$ abcde

The script will automatically download the disc's metadata (artist, album and song names, genre...), ask you to confirm them and then rip and encode the music.

Merging two avi files

To merge two avi file that have the same format (because e.g they are splitted into two CDs):

mencoder -oac copy -ovc copy file1.avi file2.avi -o output.avi

If mencoder tells you the two files do not have the same format, then the simplest method I have seen is to use avimerge, from transcode:

avimerge -o output.avi -i file1.avi file2.avi

If you see messages like:

No audiodata left for track 0->0 (6078000.00=6078000.00)

And you see that audio is out of sync, you could use the -c flag. See the manpage for more information.

Merging two mkv files

To merge two mkv files, you should use mkvmerge from MKVToolnix:

$ mkvmerge --append-mode track -o full.mkv file1.mkv '+file2.mkv'

Playing with subtitles

If you want to edit the subtitles or re-time them, the one utility I found useful is Subtitles, and its associated command line utility subs . As an example, to shift the times in a .srt file 60 seconds later, one can just do:

$ subs -b 60

Sound settings in mplayer

Use 0 and 9 to respectively increase or decrease the volume while mplayer is playing. You can use -softvol-max to adjust the maximum volume. The argument that is taken is the maximum amplification level (in percent). For example:

$ mplayer -softvol-max 2000 somefile.avi

will allow an amplification of 20 times, at the cost of some lost quality and granularity.

Extract the audio content of a video file

To get only the audio track of a video file, use mplayer's -dumpaudio:

$ mplayer -dumpaudio $videofile -dumpfile $audiofile

Since this is not always very stable, here is an alternative method using ffmpeg:

$ ffmpeg -i $videofile $audiofile

Where $audiofile should have the extension you want, e.g mp3.

Extract images from a video file

To extract images from a video file, use mplayer's -vo option:

$ mplayer -ss $interval -vo $format -frames $nframes -nosound $file


  • $interval is the number of seconds to wait between two frames. Can be a decimal number, like 0.01.
  • $format is the picture format to use. Can be for example jpeg, png, gif...
  • $nframes is the number of frames to take
  • $file is the path to your file.


$mplayer -ss 0.01 -vo jpeg -frames 5 -nosound mvi_1234.avi

will dump the first five frames of the movie mvi_1234.avi encoding them in the JPEG format, waiting 0.01 seconds between each frame.

Renaming an audio file based on ID3 tags

You can use the id3 tool to edit / read and rename file according to their ID3 tags. One command I often use to rename all files to a $track-$title.mp3 format is:

$ id3 -f '%#n-%t.mp3' *.mp3