[FFmpeg-devel] [PATCH] avfilter: Handle =help to show Filter options documentation

[Michael Niedermayer]

On Sat, Mar 30, 2013 at 02:26:22AM +0100, Stefano Sabatini wrote:
> On date Saturday 2013-03-30 01:56:08 +0100, Michael Niedermayer encoded:
> > On Sat, Mar 30, 2013 at 01:27:07AM +0100, Stefano Sabatini wrote:
> > > On date Friday 2013-03-29 17:53:57 +0100, Clément Bœsch encoded:
> > > > On Fri, Mar 29, 2013 at 05:26:19PM +0100, Michael Niedermayer wrote:
> > > > > Signed-off-by: Michael Niedermayer <michaelni at gmx.at>
> > > > > ---
> > > > >  libavfilter/avfilter.c |   14 +++++++++++++-
> > > > >  libavfilter/avfilter.h |    1 +
> > > > >  2 files changed, 14 insertions(+), 1 deletion(-)
> > > > > 
> > > > 
> > > > As said on IRC, I would prefer something like:
> > > > 
> > > >  ./ffmpeg -help filters
> > > >  ./ffmpeg -help filter=curves
> > > > 
> > > > Same with all the tools, supporting codecs, formats, etc.
> > > > 
> > > > And as a default message for -h and -help, an extended version of the "Getting
> > > > help" from ffmpeg.c, and without any option displayed unless you explicit
> > > > "full" or some module.
> > > 
> > > +1.
> > > 
> > > Also the patch is adding a special case on argument parsing (the
> > > "help" string is special) which I tend to dislike. For example we
> > > could have: "drawtext=help" to draw "help".
> > 
> > the patch interfers in no way with "drawtext=help" if thats valid for
> > drawtext
> > 
> 
> > it only prints the help text once the filter failed, which implicates
> > that "help" was not valid for the filter
> 
> This adds ad-hoc (tendentially impredictable) behavior, for a marginal
> gain.
> 
> Per component help looks more like an application level feature,
> rather than an ad-hoc feature in the library (and working only for
> filters).
> 
> > Also you can put the help text anywhere else or nowhere it makes no
> > difference, The user looked at -vf filter=help he will not see it
> > when its elsewhere.
> 
> I don't think I understand this paragraph.
> 
> > "-help filter=curves" may or may not solve some issue it does not
> > solve the issue that a random user doesnt know the curves command line
> > options because he also doesnt know the help command line options
> 
> But why the user should know that -vf filter=help will show help,
> instead of setting the arguments for the filter as it could be
> reasonably expected?

its what the user actually tried who asked for it IIRC, its what i
would try probably
its what some other applications support
try qemu for a list of cpus its
-cpu '?'
or
mplayer -vo help

[...]
-- 
Michael     GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB

DNS cache poisoning attacks, popular search engine, Google internet authority
dont be evil, please
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