On 16 September 2013 19:58, Russell Coker <russell@coker.com.au> wrote:
avconv -i foo.mkv -strict experimental -b:v 400k -c:v libx264 -b:a 80 -c:a libmp3lame -ac 1 -s 1280x720 foo-s3.mp4
I'm experimenting with avconv settings to convert movie files for watching on a mobile phone. Above is my latest experiment for converting a movie to watch on a Galaxy S3. The "-strict experimental" seems to be required to create mp4 files with the version of avconv in Debian/Unstable. The video bitrate of 400k and audio bitrate of 80k are arbitrary, I'm going to test them out and see if they are ok, as usual it's a trade-off between quality and space. The "-ac 1" sets it to a single audio channel which works well for the built-in speaker in a phone, and for a movie there isn't so much benefit in sterio (for my music video collection I use sterio because it's worth it when using headphones).
Apart from tweaking the bitrates is there anything else I can do to give a better result?
Set libx264 to use a high profile instead of standard. Use a higher-quality-but-slower encoding preset for it. (There should be a bunch of those in /usr/share somewhere, at least there are on Ubuntu with the Medibuntu versions of avconv installed)
avconv -i foo.mkv -strict experimental -s 1280x720 foo-s3.mp4
As an aside avconv doesn't seem to work with basic commands such as the above when a mkv file is the input, but specifying video and audio encoding options separately fixes it.
That might be because Matroska is a container specification, not an encoder specification? Perhaps avconv isn't sure what path to take to make an mp4. ALthough you'd hope it would introspect the streams inside the mkv to determine that. T