Hi! First of all, I may say that everything I will mention here is from reading the code. The only docs I have found on this are:
1. http://www.musicpd.org/doc/developer/ Which gives coding guidelines 2. http://www.musicpd.org/doc/api/html/ Which just documents a part of the code, nothing directly regarding the plugins 3. http://www.musicpd.org/doc/user/ch05.html Which is much more complete (for the user). Having the docs into account, the code I read, and a conversation I had with cirrus (irc) yesterday, I want to ask, first of all, if there is any other docs I have missed. Then, what regards the mpd plugins. Some definitions I have learnt, if you can confirm or correct them, I would much appreciate it: - Archive plugin: It is in charge of getting input streams from compressed blocks - Database plugin: Is in charge of saving and gathering the Library, made up of: song meta, song uri, playlists and directories. It is also used for searching in the Database - Filter plugin: It is to transform PCM data - Input plugin: It converts from URIs to real PCM data - Mixer plugin: It controls the output volume - Output plugin: It controls the output device and the data it is passed to it - Playlist plugin: It converts from playlist uri to internal mpd playlist format, and is able to use that format to gather songs I haven't understood much about the DatabasePlugin. What is to Visit()? I thought it was to search, but I was told Visit() would only sometimes be equivalent. I have tried reading the code but is not too clear to me. > /** > * Visit the selected entities. > */ > virtual bool Visit(const DatabaseSelection &selection, > VisitDirectory visit_directory, > VisitSong visit_song, > VisitPlaylist visit_playlist, > GError **error_r) const = 0; The definition of Visit() is this (the others are calling this). The DatabaseSelection is defined like this: > struct DatabaseSelection { > const char *uri; > bool recursive; > const SongFilter *filter; > > DatabaseSelection(const char *_uri, bool _recursive, > const SongFilter *_filter=nullptr) > :uri(_uri), recursive(_recursive), filter(_filter) { > assert(uri != NULL); > } > > gcc_pure > bool Match(const song &song) const; > }; So If I want to search in that DatabasePlugin, I may create a SongFilter, with it, create a DatabaseSelection struct, and then I still have to fill up the Visit* args. Those Visit* arguments are defined as: > typedef std::function<bool(const Directory &, GError **)> VisitDirectory; > typedef std::function<bool(struct song &, GError **)> VisitSong; > typedef std::function<bool(const PlaylistInfo &, const Directory &, > GError **)> VisitPlaylist; > > typedef std::function<bool(const char *, GError **)> VisitString; Which for me mean: - VisitDirectory: A directory to search on - VisitSong: I don't understand this arg, because DatabasSelection already has what to search for - VisitPlaylist: I don't understand this - VisitString: Neither understand I promise I have tried hard trying to understand mpd's internals, but got stuck here. Really stuck. Any clarifications you make I would much appreciate them, Cheers, Javier Domingo Cansino Research & Development Junior Engineer Fon Labs Workgroup, Getxo - Spain. ------------------------------------------------------------------------------ This SF.net email is sponsored by Windows: Build for Windows Store. http://p.sf.net/sfu/windows-dev2dev _______________________________________________ Musicpd-dev-team mailing list Musicpd-dev-team@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/musicpd-dev-team
