[FFmpeg-devel] [PATCH] Move stream_options to avformat

Michael Niedermayer michaelni at gmx.at
Sun Jan 25 03:08:16 CET 2015


On Sun, Jan 25, 2015 at 02:31:33AM +0100, wm4 wrote:
> On Sun, 25 Jan 2015 02:28:01 +0100
> Michael Niedermayer <michaelni at gmx.at> wrote:
> 
> > On Sun, Jan 25, 2015 at 02:16:58AM +0100, wm4 wrote:
> > > On Sun, 25 Jan 2015 01:56:30 +0100
> > > Michael Niedermayer <michaelni at gmx.at> wrote:
> > > 
> > > > TODO: APIChanges/version bump
> > > > 
> > > > Signed-off-by: Michael Niedermayer <michaelni at gmx.at>
> > > > ---
> > > >  ffmpeg.c               |   30 ++++--------------------------
> > > >  libavformat/avformat.h |    6 ++++++
> > > >  libavformat/options.c  |   30 ++++++++++++++++++++++++++++++
> > > >  3 files changed, 40 insertions(+), 26 deletions(-)
> > > > 
> > > > diff --git a/ffmpeg.c b/ffmpeg.c
> > > > index b836448..af576c7 100644
> > > > --- a/ffmpeg.c
> > > > +++ b/ffmpeg.c
> > > > @@ -2970,32 +2970,10 @@ static int transcode_init(void)
> > > >          }
> > > >  
> > > >          if (ost->disposition) {
> > > > -            static const AVOption opts[] = {
> > > > -                { "disposition"         , NULL, 0, AV_OPT_TYPE_FLAGS, { .i64 = 0 }, INT64_MIN, INT64_MAX, .unit = "flags" },
> > > > -                { "default"             , NULL, 0, AV_OPT_TYPE_CONST, { .i64 = AV_DISPOSITION_DEFAULT           },    .unit = "flags" },
> > > > -                { "dub"                 , NULL, 0, AV_OPT_TYPE_CONST, { .i64 = AV_DISPOSITION_DUB               },    .unit = "flags" },
> > > > -                { "original"            , NULL, 0, AV_OPT_TYPE_CONST, { .i64 = AV_DISPOSITION_ORIGINAL          },    .unit = "flags" },
> > > > -                { "comment"             , NULL, 0, AV_OPT_TYPE_CONST, { .i64 = AV_DISPOSITION_COMMENT           },    .unit = "flags" },
> > > > -                { "lyrics"              , NULL, 0, AV_OPT_TYPE_CONST, { .i64 = AV_DISPOSITION_LYRICS            },    .unit = "flags" },
> > > > -                { "karaoke"             , NULL, 0, AV_OPT_TYPE_CONST, { .i64 = AV_DISPOSITION_KARAOKE           },    .unit = "flags" },
> > > > -                { "forced"              , NULL, 0, AV_OPT_TYPE_CONST, { .i64 = AV_DISPOSITION_FORCED            },    .unit = "flags" },
> > > > -                { "hearing_impaired"    , NULL, 0, AV_OPT_TYPE_CONST, { .i64 = AV_DISPOSITION_HEARING_IMPAIRED  },    .unit = "flags" },
> > > > -                { "visual_impaired"     , NULL, 0, AV_OPT_TYPE_CONST, { .i64 = AV_DISPOSITION_VISUAL_IMPAIRED   },    .unit = "flags" },
> > > > -                { "clean_effects"       , NULL, 0, AV_OPT_TYPE_CONST, { .i64 = AV_DISPOSITION_CLEAN_EFFECTS     },    .unit = "flags" },
> > > > -                { "captions"            , NULL, 0, AV_OPT_TYPE_CONST, { .i64 = AV_DISPOSITION_CAPTIONS          },    .unit = "flags" },
> > > > -                { "descriptions"        , NULL, 0, AV_OPT_TYPE_CONST, { .i64 = AV_DISPOSITION_DESCRIPTIONS      },    .unit = "flags" },
> > > > -                { "metadata"            , NULL, 0, AV_OPT_TYPE_CONST, { .i64 = AV_DISPOSITION_METADATA          },    .unit = "flags" },
> > > > -                { NULL },
> > > > -            };
> > > > -            static const AVClass class = {
> > > > -                .class_name = "",
> > > > -                .item_name  = av_default_item_name,
> > > > -                .option     = opts,
> > > > -                .version    = LIBAVUTIL_VERSION_INT,
> > > > -            };
> > > > -            const AVClass *pclass = &class;
> > > > -
> > > > -            ret = av_opt_eval_flags(&pclass, &opts[0], ost->disposition, &ost->st->disposition);
> > > > +            const AVClass *pclass = avstream_get_class();
> > > > +            const AVOption *o = av_opt_find(&pclass, "disposition", NULL, 0, 0);
> > > > +
> > > > +            ret = av_opt_eval_flags(&pclass, o, ost->disposition, &ost->st->disposition);
> > > >              if (ret < 0)
> > > >                  goto dump_format;
> > > >          }
> > > > diff --git a/libavformat/avformat.h b/libavformat/avformat.h
> > > > index db72c18..e6cd301 100644
> > > > --- a/libavformat/avformat.h
> > > > +++ b/libavformat/avformat.h
> > > > @@ -1895,6 +1895,12 @@ void avformat_free_context(AVFormatContext *s);
> > > >  const AVClass *avformat_get_class(void);
> > > >  
> > > >  /**
> > > > + * Get the AVClass for AVStream. It can be used in combination with
> > > > + * AV_OPT_SEARCH_FAKE_OBJ for examining options.
> > > > + */
> > > > +const AVClass *avstream_get_class(void);
> > > > +
> > > > +/**
> > > >   * Add a new stream to a media file.
> > > >   *
> > > >   * When demuxing, it is called by the demuxer in read_header(). If the
> > > > diff --git a/libavformat/options.c b/libavformat/options.c
> > > > index 5044043..d10226d 100644
> > > > --- a/libavformat/options.c
> > > > +++ b/libavformat/options.c
> > > > @@ -130,3 +130,33 @@ const AVClass *avformat_get_class(void)
> > > >  {
> > > >      return &av_format_context_class;
> > > >  }
> > > > +
> > > > +static const AVOption stream_options[] = {
> > > > +    { "disposition"         , NULL, 0, AV_OPT_TYPE_FLAGS, { .i64 = 0 }, INT64_MIN, INT64_MAX, .unit = "flags" },
> > > > +    { "default"             , NULL, 0, AV_OPT_TYPE_CONST, { .i64 = AV_DISPOSITION_DEFAULT           },    .unit = "flags" },
> > > > +    { "dub"                 , NULL, 0, AV_OPT_TYPE_CONST, { .i64 = AV_DISPOSITION_DUB               },    .unit = "flags" },
> > > > +    { "original"            , NULL, 0, AV_OPT_TYPE_CONST, { .i64 = AV_DISPOSITION_ORIGINAL          },    .unit = "flags" },
> > > > +    { "comment"             , NULL, 0, AV_OPT_TYPE_CONST, { .i64 = AV_DISPOSITION_COMMENT           },    .unit = "flags" },
> > > > +    { "lyrics"              , NULL, 0, AV_OPT_TYPE_CONST, { .i64 = AV_DISPOSITION_LYRICS            },    .unit = "flags" },
> > > > +    { "karaoke"             , NULL, 0, AV_OPT_TYPE_CONST, { .i64 = AV_DISPOSITION_KARAOKE           },    .unit = "flags" },
> > > > +    { "forced"              , NULL, 0, AV_OPT_TYPE_CONST, { .i64 = AV_DISPOSITION_FORCED            },    .unit = "flags" },
> > > > +    { "hearing_impaired"    , NULL, 0, AV_OPT_TYPE_CONST, { .i64 = AV_DISPOSITION_HEARING_IMPAIRED  },    .unit = "flags" },
> > > > +    { "visual_impaired"     , NULL, 0, AV_OPT_TYPE_CONST, { .i64 = AV_DISPOSITION_VISUAL_IMPAIRED   },    .unit = "flags" },
> > > > +    { "clean_effects"       , NULL, 0, AV_OPT_TYPE_CONST, { .i64 = AV_DISPOSITION_CLEAN_EFFECTS     },    .unit = "flags" },
> > > > +    { "captions"            , NULL, 0, AV_OPT_TYPE_CONST, { .i64 = AV_DISPOSITION_CAPTIONS          },    .unit = "flags" },
> > > > +    { "descriptions"        , NULL, 0, AV_OPT_TYPE_CONST, { .i64 = AV_DISPOSITION_DESCRIPTIONS      },    .unit = "flags" },
> > > > +    { "metadata"            , NULL, 0, AV_OPT_TYPE_CONST, { .i64 = AV_DISPOSITION_METADATA          },    .unit = "flags" },
> > > > +    { NULL },
> > > > +};
> > > > +
> > > > +static const AVClass av_stream_class = {
> > > > +    .class_name     = "AVStream",
> > > > +    .item_name      = av_default_item_name,
> > > > +    .option         = stream_options,
> > > > +    .version        = LIBAVUTIL_VERSION_INT,
> > > > +};
> > > > +
> > > > +const AVClass *avstream_get_class(void)
> > > > +{
> > > > +    return &av_stream_class;
> > > > +}
> > > > \ No newline at end of file
> > > 
> > > As an experienced API user, I don't have the slightest clue what I'd do
> > > with this API, or where to find information about it.
> > 
> > the primary goal is to remove duplicated disposition type tables,
> > which needs one of the tables to be public first
> > 
> > [...]
> 
> And this is the most awkward way you could find to do this?

No, i could certainly find a more akward way, if people prefer

this is just the way that would be a big step towards consistent
and simple access to the structs
All public structs use AVClass and AVOptions to allow applications
to extract/enumerate fields except a few like AVStream
this patch would add these AVClass & AVOption for AVStream, its
indeed not populated for all fields and AVStream doesnt have a
AVClass as its first field due to ABI. But its a step toward it

Would people prefer that each field in AVStream has a custom and
different way to access it, as long as it looks simpler when looked
at in isolation ?

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

I am the wisest man alive, for I know one thing, and that is that I know
nothing. -- Socrates
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