[FFmpeg-devel] [PATCHv2 1/5] avcodec: add side_data type for updated metadata

[Reimar Döffinger]

On Sat, Oct 26, 2013 at 01:58:07PM +0200, wm4 wrote:
> On Fri, 25 Oct 2013 22:18:04 -0400
> Ben Boeckel <mathstuf at gmail.com> wrote:
> 
> > This type is intended to be used to allow codecs to pass updated
> > metadata to applications.
> > 
> > Signed-off-by: Ben Boeckel <mathstuf at gmail.com>
> > ---
> >  libavcodec/avcodec.h | 6 ++++++
> >  1 file changed, 6 insertions(+)
> > 
> > diff --git a/libavcodec/avcodec.h b/libavcodec/avcodec.h
> > index b64331d..f78475e 100644
> > --- a/libavcodec/avcodec.h
> > +++ b/libavcodec/avcodec.h
> > @@ -1012,6 +1012,12 @@ enum AVPacketSideDataType {
> >       * follow the timestamp specifier of a WebVTT cue.
> >       */
> >      AV_PKT_DATA_WEBVTT_SETTINGS,
> > +
> > +    /**
> > +     * A list of zero terminated key/value strings. There is no end marker for
> > +     * the list, so it is required to rely on the side data size to stop.
> > +     */
> > +    AV_PKT_DATA_METADATA_UPDATE,
> >  };
> >  
> >  /**
> 
> Looks ok, but I think the comment should also say that it updates
> AVStream.metadata.

Actually I'd kind of appreciate some documentation on what its purpose
is.
I mean, if it's just to signal that the .metadata entry was updated, I
would guess you could put that e.g. as a flag into the context/packet?
I mostly wonder what the basic design idea/philosophy is for doing it
that way, and I think that kind of information will be useful to have
in the comment, otherwise users will just get incredibly confused when
there are multiple ways to get metadata with no good explanation why
there is more than one and they can't decide which to support...