Free software source video encoding with Ogg Theora and Vorbis
Note
ffmpeg2theora is discontinued commandline converter for creating Ogg Theora video files. The better current alternative for this purpose, if you still want to create Ogg Theora files for some reason, would be ffmpeg, see my followup article. Further, the free modern choice for web video is VP9 video with Opus audio in a Webm container. Ogg Theora isn’t very modern. ffmpeg2theora has not been updated since 2016.
The free software software Theora video codec, can together with the Vorbis audio codec and the Ogg container format produce very small files with good quality.
![Theora logo](/images/theorafish.png)
Most high-performance video codecs are encumbered with patents. Not so long ago, a new version of the Theora video codec was released with improved performance. I tested it with version 0.25 of ffmpeg2theora, which creates files with Vorbis sound and Theora video.
The mpg
file was produced with
mplayer dvd://1 -dumpstream -dumpfile movie.mpg
Converting to avi
format was done with:
mencoder -profile hqmovie -o movie.avi movie.mpg
This profile is covered further down on this page. The ogv
file was
created with the command:
ffmpeg2theora --sync --aspect 16:9 --croptop 8, --cropbottom 8 -v 7 -c2 movie.mpg
The difference in size between the avi
and the ogv
file is impressive,
especially since I cannot see much difference in quality. The only snag is
that mencoder seems to do a better job of creating a better sounding stereo
sound from e.g. a AC3 stream. Therefore I tend to do a quick resample of only
the sound with:
mencoder -ovc copy -oac mp3lame -idx -o movie-int.avi movie.mpg
Filename | Format | Remarks | Size |
---|---|---|---|
movie.mpg | MPEG2+AC3 | as ripped | 6478 MiB |
movie-int.avi | MPEG2+MP3 | sound resampled to MP3 | 5806 MiB |
movie.avi | H.264 +MP3 | by mencoder (from original MPG) | 4481 MiB |
movie.ogv | Theora/Vorbis | by ffmpeg2theora (from original MPG) | 1999 MiB |
movie2.ogv | Theora/Vorbis | by ffmpeg2theora (from resampled AVI) | 1750 MiB |
I cannot see or hear much of a difference between the H.264+MP3 encoded movie
and the one encoded with Theora+Vorbis. The H.264 avi
file made by
mencoder is 70% of the size of the original mpg
file. The ogv
files
are 30% of the size of their original mpg
files, and are in my eyes of
equal quality to the H.264 encodd AVI files. And since Ogg/Theora is not
encumbered with patents like H.264, it makes me think that theora+vorbis is a
better choice for encoding video now. I’ve encoded other movies as well, and
constantly find that the size of the theora+vorbis encoded film is around
30-40% of the size of a H.264+MP3 encoding.
For feature films, file size in this OGV format range from 1051 MiB for a 97 minute standard format movie, via 1750 MiB for a 147 minute widescreen movie to 2988 MiB for a 207 minute black/white movie.
For comments, please send me an e-mail.