[Flac-dev] libflac++ reading vorbis metadata

[Josh Coalson]

--- Emil Nowak <emil5 at go2.pl> wrote:
> On 2006-03-09 (Thu) ,at 23:20:50 Josh Coalson wrote:
> 
> > the vorbiscomments are not in the streaminfo.  you want to do:
> > 
> > FLAC::Metadata::VorbisComment tags;
> > if (FLAC::Metadata::get_tags("somefile.flac", tags)) {
> >    FLAC::Metadata::VorbisComment::Entry entry =
> >       tags->get_comment(tags->get_num_comments-1); //e.g. last tag
> >    // do something with it...
> > }  	
> > 
> > Josh
> Oki, thanks it works. However I still have some questions about all
> the
> libflac++. If this is impossible to read vorbis info from StreamInfo
> why there
> is constructor for VorbisComment which takes StreamInfo as the only
> argument?

c++ constructors cannot return values so the only thing it
could do is throw an exception or make you have to call an
invariant checker method after construction, neither of
which I like.

the path that allowed a vorbiscomment into a streaminfo at compile
time was implicit conversion to ::FLAC__StreamMetadata which is
unfortunately necessary for the 'wrapper' behavior around libFLAC
to work smoothly.

even in the beginning I would rather have written libFLAC in C++
but went with C for maximum portability.

> And why the get_num_comments() on this object returns number > 0, if
> there are no comments?

it was reading into bogus memory.

> And BTW: Documentation for libflac++ on official site is generated
> from some
> old sources, or wrongly generated - You don't have all doxygened
> informations
> that is available in headers. 
> Anyway even with this improved documentation (which I have locally)
> It's hard
> to get all needed information, many methods are not described, many
> datatypes
> are not linked here. I was even using grep on headers, to get some
> information. And there are so many footnotes like "read C
> documentation first"
> that I decided, to do everything in C. It seems to be impossible to
> use
> flac++ without learning ordinary libflac.

yeah, I need to fill in more of the libFLAC++ docs.  but it
really does work as a trivial wrapper around libFLAC and it's
not practical to duplicate all the docs, that's why there are
pointers into the underlying libFLAC docs for explanation.

Josh


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