[MEncoder-users] x264encopts equivalent for some x264 parameters ?

[Corey Hickey]

Pierre Catello wrote:
>> > I can't find in the doc how to use in MEncoder the equivalent of this
>> x264
>> > mode :
>> > --crf -q x (x belonging to [0..1])
>>
>> -x264encopts crf=x
>>
>> That sort of information is in the man page.
> 
> What you are are saying is that "x264 --crf 18 -q 0.75" is equivalent to
> "MEncoder -x264encopts crf=0.75"

No, that x264 command is invalid because -q requires an integer argument.

$ x264 --crf 18 -q 0.75 -o test.264 stream.yuv 852x362
x264 [error]: invalid argument: qp = 0.75

Actually, I was careless and didn't quite parse your original question 
properly. What you had written before (--crf -q x) is actually a syntax 
error, though, so I'm still not quite sure what you mean.

$ x264 --crf -q 1 -o test.264 stream.yuv 852x362
x264 [error]: invalid argument: crf = -q

...because --crf requires a numeric argument, and x264 parses '-q' as 
that argument.

"--crf x" and "-q x" specify two different and mutually exclusive modes 
of operation. If you specify them both on the same line, the latter 
takes precedence and the former is ignored (according to a quick test I 
just did).

If you don't understand the difference between --crf and -q, ask and 
I'll explain. --But first read the descriptions of crf and qp in the 
mplayer man page.

> Isn't qcomp the equivalent of -q ?

No; unless I'm gravely mistaken, qcomp is the equivalent of --qcomp.

x264        mencoder (-x264encopts ...)
----------------------------------------
-q x        qp=x
--crf x     crf=x
--qcomp x   qcomp=x

> BTW, RTFM -style comments are useless, and worse, misleading.

That depends; for a complicated program with lots of documentation in 
several different places, pointing out a specific document (as I did) 
can be quite helpful. If you need further help, you have to ask a 
question that indicates you've read the relevant part of the 
documentation and still don't understand. There's nothing wrong with not 
understanding documentation--the material is complex.

-Corey