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

[Stefano Sabatini]

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?
-- 
FFmpeg = Faithful & Forgiving Meaningless Problematic Ecstatic Gigant