[FFmpeg-cvslog] Merge commit '85770f2a2651497861ed938efcd0df3696ff5e45'

[Peter Ross]

On Sun, May 01, 2011 at 02:04:58AM +0200, Stefano Sabatini wrote:
> On date Sunday 2011-05-01 01:01:30 +0200, Stefano Sabatini wrote:
> > On date Sunday 2011-05-01 00:27:06 +0200, Michael Niedermayer wrote:
> > > ffmpeg | branch: master | Michael Niedermayer <michaelni at gmx.at> | Sun May  1 00:21:56 2011 +0200| [ffb5a0d533498102c31aa131bc91a4cce868b0a8] | committer: Michael Niedermayer
> > > 
> > > Merge commit '85770f2a2651497861ed938efcd0df3696ff5e45'
> > > 
> > > * commit '85770f2a2651497861ed938efcd0df3696ff5e45':
> > >   AVOptions: make default_val a union, as proposed in AVOption2.
> > >   Move ff_dynarray_add to lavu and make it public.
> > >   lavf: remove duplicate assignment in avformat_alloc_context.
> > >   lavf: use designated initializers for AVClasses.
> > >   options: simplify av_find_opt by using av_next_option.
> > > 
> > > Merged-by: Michael Niedermayer <michaelni at gmx.at>
> > > 
> > > > http://git.videolan.org/gitweb.cgi/ffmpeg.git/?a=commit;h=ffb5a0d533498102c31aa131bc91a4cce868b0a8
> > > ---
> > 
> > Why did you remove .i64 and .q from the default_val union?
> > 
> > For the rational it is more safe/logical not assume sizeof(double) >=
> > sizeof(int64_t), for the second it may be convenient to express a
> > default by using a rational rather than its double representation, for
> > documentation/convenience purposes.
> 
> String default value setting doesn't work, that's because
> av_set_string3() doesn't accept NULL values for val, so for example:
> 
> av_set_string3(obj, name, NULL, 1, NULL);
> 
> will always return AVERROR(EINVAL).
> 
> Here there is a problem since you can't represent a NULL value string
> with a string safely, you could set "" but that's not the very same
> thing.

But you could define a valid string that FFmpeg treats always as NULL.

e.g.

avcodec/string.h
extern const char * av_null_string;

avutil/string.c
const char *av_null_string = "(null)";

av_set_string(..)

    if (str == av_null_string)

        behave this way

-- Peter
(A907 E02F A6E5 0CD2 34CD 20D2 6760 79C5 AC40 DD6B)
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