[Ffmpeg-devel] [PATCH] Use ff_eval for AVOption parsing

[Panagiotis Issaris]

Hi,

Op dinsdag 26 september 2006 16:43, schreef M?ns Rullg?rd:
>[...]
> > Is it okay to commit this one? It does cause some extra output...
> >
> > ../ffmpeg_g -y -flags +bitexact -dct fastint -idct simple -y -qscale 10 -f
> > pgmyuv -i vsynth1/%02d.pgm -an -vcodec msmpeg4v2 ./data/a-msmpeg4v2.avi
> > FFmpeg version SVN-rUNKNOWN, Copyright (c) 2000-2004 Fabrice Bellard
> >   configuration:  --enable-gpl --enable-x264 --enable-pthreads
> >   libavutil version: 49.0.1
> >   libavcodec version: 51.15.0
> >   libavformat version: 50.5.0
> >   built on Sep 26 2006 16:07:52, gcc: 4.0.3 (Ubuntu 4.0.3-1ubuntu5)
> > Parser: missing ( in "bitexact"
> > Parser: missing ( in "fastint"
> > Parser: missing ( in "simple"
> 
> That looks rather bad.  Are you sure this is working?
Yes, it works alright, but it is annoying. The reason it is displaying these 
messages, is that ff_eval does not understand what these are and complains 
about it. The avoptions parsing code parses these, as they are of type 
FF_OPT_TYPE_INT, as "auto", "fastint", etc are shorthands for 0, 1, etc.

If on the commandline the parameter "-dct simple" is specified, this results in
a call to: av_set_string(x, "dct", "simple")
As it is an AVOption of type FF_OPT_TYPE_INT, the value will be parsed as if it
was a number (which it could have been). The parser then depends (and has 
always depended) on the failing of this parsing to use the value ("simple") as
the name of an avoption (you can see this at line 187 of libavcodec/opt.c).

The thing I'm changing is the replacement of strtod() with ff_eval() so more
complex expressions can be parsed. The strtod() function does _not_ output 
anything if it can't parse the string it has been given. ff_eval() does, which
is why these messages are appearing.

With friendly regards,
Takis