[vlc-devel] Re: [RFC] playlist current playing item for JS API

[Clément Stenac]

Jean-Paul Saman wrote:
> Zorglub,
>
> I need your comments on attached patch. The idea is to let a JS 
> programmer get information (incl. meta information like: media length, 
> index, name) on the current playing item.
>
> The patch currently expose playlist_item_t to the control api that we 
> use in the browser plugins. I don't know if this is supposed to be 
> done, so please comment on this.
>
Having this kind of info is suer needed, but I'm opposed to exposing the 
playlist_item_t structure. playlist_item_t is an internal structure that 
we should not tie to our public API. Moreover, exposing playlist_item_t 
means that you will also need to expose a huge number of internal 
structures (starting with input_item_t, then vlc_meta_t, 
input_category_t, es_format_t, vlc_mutex_t, libvlc_t, ...).

What I wanted to do but did not complete was one of the two following 
solutions:

* only expose to the client an abstract structure identifying the item. 
The client then only uses API functions to retrieve the fields, like:
   char* libvlc_playlist_get_item_uri(libvlc_instance_t*, libvlc_itemid_t)
* copy the required information to an external, stable structure and 
pass that to the client, like
   libvlc_itemdescr_t* libvlc_playlist_get_iteminfo(libvlc_instance_t*, 
libvlc_itemid_t)

I think I prefer the first solution, which can be efficient if 
implemented with a cache. I think it's better because we can add new 
libvlc_playlist_get_item_* functions without breaking both API and ABI 
in a backwards-incompatible way.

Clément

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