11-22-2008
We will be using 3 tools: transcode, mplayer's mencoder and ffmpeg - all commandline tools. Anybody who has been keeping track of this journal should by now be aware that if I can, I avoid GUI point-n-click apps like the plague. Lastly, this mini howto is by no means exhaustive.
Basics
mencoder
-ovc codec for video output
-oac codec for audio output
-o outfile.avi
mencoder infile.avi -ovc lavc -oac lavc -o outfile.avi
transcode
-i input_filename.mpg
-y codec for audio/video output
-o output_filename.avi
transcode -i infile.mpg -o outfile.avi -y divx
ffmpeg
ffmpeg -i myfile.avi -target vcd /tmp/vcd.mpg
Video CD
ffmpeg -i infile.avi -target ntsc-vcd outfile.mpg
Flash Videos
ffmpeg -i infile.mpg -ab 256 outfile.flv
*note:
Use the “-ab” switch to control the sound quality. 64 is okay for home vidoes. For music you want something higher like 256.
XviD
First, something about video bitrates.
Crummy youtube-like video is around 80-150.
VCD quality is around 400-500.
DVD quality is approx 800.
Default bitrate for mencoder is 687kbps.
mencoder infile.avi -ovc xvid -oac mp3lame -xvidencopts bitrate=687 -o outfile.avi
*notes:
If you want the outfile to have an estimated size (like 700mb), set a negative bitrate and replace the bitrate value with the expected size of the outfile like:
-bitrate=-700000 - will give you a ~700mb avi file.
Two-pass encodings will give a nicer video but will take longer to convert:
mencoder infile.wmv -ofps 23.976 -oac mp3lame -lameopts abr:br=92 -ovc xvid -xvidencopts pass=2:bitrate=150 -o audiofix-150bit-xvid.avi
Audio quality can be set via the -lameopts switch if you're using mp3lame (-oac mp3lame) for the audio format:
mencoder infile.avi -ovc xvid -oac mp3lame -lameopts abr:br=256 -xvidencopts bitrate=800 -o outfile.avi
Microsoft media files (*.wmv, *.asf, *.wmx)
Just follow the howto for Xvid and replace the infile.avi with any M$.wmv file you have. There's an issue regarding some players (Xine) not being able to play wmv->xvid files converted using mencoder. Just use the -ofps 23.976 switch for that.
DivX
transcode -i infile.mpg -o outfile.avi -y divx
DVD
ffmpeg -i infile.avi -target ntsc-dvd dvd.mpg
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