Re: [Libcdio-devel] CD-Text API changes

[Leon Merten Lohse]

On Sun, Feb 26, 2012 at 06:23:32PM -0500, Rocky Bernstein wrote:
> Thank you very much for this write up. I really appreciate it.
> 
> Some thoughts with regards to the questions I asked and the concerns
> Nicolas raised. Your current corrected code reads all blocks whereas the
> old code read only the first block. I imagine there are a number of cases
> where the first block was good enough (or at least better than nothing). So

I would say in most cases the first block is all there is. But we cannot
really claim to fully support CD-Text if our implementation is missing
that feature.

> here, from a programming standpoint there is no change. And there are
> features such as multiple language support that the old code just couldn't
> handle. The main place that is incompatibility is in cdtext_get(). Although

This is partly correct. One the one hand we have the
libcdio_get_cdtext() method that reads the text from the disc and
returns a cdtext_t struct. The point is this struct is completely
different from the old one. On the other hand there are the cdtext_* functions, 
cdtext_get[_const] expect the track parameter now. Essentially this parameter 
moved 
from cdio_get_cdtext to cdtext_*, allowing cdtext_t to store the data of
all tracks.

> I totally understand the reason for this change, if another name were used,
> that might reduce incompatibility and confusion. Right? And the old
> (incomplete) function could be simulated by the new one by supplying a
> track parameter. Correct?

It is not that simple. We also would have to give cdtext_t a new name
and the cdtext_* functions, too.
If this was a widely used feature, I would totally agree and note them
as deprecated with the option to remove them in later releases but in
this case I would like to avoid it.

> As far as places where the that used the old libcdio cdtext code is used
> (outside of libcdio such as cd-info), I wrote some plugins for xine, and
> vlc. The xine plugin I don't think was ever mainstream. Googling around for
> CD-Text on vlc seems to show this was broken, so perhaps I will investigate
> and update the code. There is also a libcdio-based plugin for gstreamer.
> These are largely the uses I know of. If there are others, of course I'd
> like to know about.

If one of them is still in use, I offer to adapt it. Most of it is
search & replace. How broken is the VLC one? Can it be fixed in
reasonable time. Would be nice to actually have a working example of
multilanguage CD-text.

> 
> Nicolas: your thoughts here with respect to Leon's changes?