[FFmpeg-user] formula for transcoding to ogv, shrinking an mkv

[Carl Eugen Hoyos]

James Miller <gajs-f0el <at> dea.spamcon.org> writes:

> > If you have a target filesize, don't use a constant
> > quantiser, but specify a bit-rate (calculated by you)
> > and use 2-pass encoding.
> 
> Thank you for your response, which I am trying to interpret. According to 
> some research I've done in that effort, the -crf option in my formula is 
> probably what you're referring to as a "constant quantizer"; is that 
> correct? I've also gathered that, instead of using this, I should use the 
> -b option followed by some numerals in order to get a certain bit-rate. 
> Correct? Can you recommend any basic documentation on 2-pass encoding?

The MEncoder documentation is old and therefore by 
definition a bit out-dated but it contains many 
information to basic strategies:
http://www.mplayerhq.hu/DOCS/HTML/en/menc-feat-dvd-mpeg4.html#menc-feat-dvd-mpeg4-2pass

> > Please note that for all questions on this mailing
> > list, you should add complete, uncut console output
> > together with your command line.
> 
> Hmmm. I'm a little puzzled by this stipulation. When I run my command in 
> the console, I get several lines that give specifics about the 
> characteristics of the file being processed and about what ffmpeg is 
> preparing to perform on it. That, on successful attempts (like the one I 
> posted about), is followed by a sort of progress meter that runs until the 
> transcoding is finished. Are you saying I should copy and paste all that 
> into any query I make to this list?

Yes.
(This is of course a little simplified and there 
probably are situations where it is unneeded but 
it is a good idea to always post it.)

Carl Eugen