[Ffmpeg-devel] Differences between mencoder and ffmpegwhenencoding using x264

Robert Swain robert.swain
Tue Feb 21 11:45:26 CET 2006

On Tuesday 21 February 2006 10:16, Erik Slagter wrote:
> On Tue, 2006-02-21 at 03:45 +0000, Robert Swain wrote:
> > I did this because qscale means nothing to me while I (and other x264
> > users to my knowledge) are much more familiar with 'qp's. 'qscale' was
> > originally used but as most x264 users (due to use of the cli or
> > mencoder) I changed it to cqp. I will take all the flak for this
> > decision.
> [ ... ]
> > As Loren said, x264 uses the subme option to control such techniques and
> > as such I tried to avoid use of *cmp.
> Hmmm, maybe an idea, if these (mpeg4-specific) parameters are used for
> h264 encoding, to either submit a warning or silently try to the
> translate the parameters into h264 semantics as much as possible?
> Currently nothing is reported and the supplid values are silently
> ignored, which is imho very wrong, because the user (me ;-)) has no clue
> what's going on!

I don't know what would be preferred in FFmpeg. The parameters that *cmp refer 
to are tuned internally in x264. The *cmp parameters can have no sensible 
affect on it currently as those such options are fixed. Sorry. :) The only 
option would be to provide some warning, I suppose.

It wouldn't be so bad if I'd documented the options though I don't know how 
many people would look at the docs for FFmpeg as it's not exactly current as 
far as I know and is the main reason I continually recommend mencoder to 
people. I would expect you to be at least aware that x264 is not an FFmpeg 
codec and so you should not expect it to work precisely in the same framework 
in terms of its parameters. I agree that usability is an issue but I think 
the x264 interface is perfectly usable and atrociously documented and I will 
look into a solution at some point. It probably won't be any time soon though 
as I have coursework deadlines imminent and then a whole shed load of exams. 
Yey for the final year of degrees. :)


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