MPD Query

So I mentioned in another post that I use mpd and ncmpcpp to listen to music. The positive thing about this is that I can just close ncmpcpp when I don’t need it anymore and the music will continue playing, since mpd is responsible for the sound which is running completely in the background. Now sadly I have no indicator about what song is playing right now.

So I looked if anybody made a patch for dwm to display the current song, but everything I found didn’t really work for me. And I didn’t want a bash script to be running in the background. So I found a few people suggesting to make a simple C program to query the current song.

Now this is easier said than done, since I have no idea how to use mpd and C. The first thing I did was download the source code of mpd and copied the include directory into my project folder. So now I can write a program utilizing code from mpd. Now for the tricky part: Getting my program to connect to mpd and get the song name and some other information. I had some example code which showed how to connect and get the play time of the current song, so that helped a little bit, but getting the song name doesn’t work the same way.

For experienced people this task probably would be a thing of ten minutes but I not only had to deal with how mpd worked I also had to figure out how C works. And most time that was me writing like three lines of code, compiling it and fining out it compiled fine but crashed when running. So here’s what I have done so far:

Created a Makefile where the include directory is:

VERSION = 3.02
CC      = /usr/bin/gcc

mpdq: mpdq.c
$(CC) -o mpdq -lmpdclient mpdq.c

So this way compiling is just the command ‚make‘. Next up is writing the actual code which started by me finding out how the main method looks in C and then moving onto actually fiddling with mpd. To work with mpd I needed these two headers:

#include <mpd/client.h>
#include <mpd/stats.h>

When those are included and the compiler doesn’t complain about not finding them you should be able to access the necessary methods to connect and query information from mpd:

struct mpd_connection  *connection = mpd_connection_new(NULL, 0, 0);

This will open a connection to the local mpd and return the pointer to the connection if it succeeded. The three arguments are only needed if the connection is to another computer. After that we want to get the current song and from that we can read most Song tags:

// Get current song as a struct
struct song = mpd_run_current_song(connection);
// Read name and artist
char *song_name   = (char *) mpd_song_get_tag(song, MPD_TAG_TITLE, 0);
char *artist_name = (char *) mpd_song_get_tag(song, MPD_TAG_ARTIST, 0);

And that is technically everything important to read information from mpd. The only other things I did were putting this in a loop, adding a command to make it appear in the dwm bar, differentiating between paused/playing and  cleaning up when closing. That’s all I have done up until now. I’ll see if I can get some controls like pause/play into the dwm bar but for now this’ll suffice.

Here’s the source code and here’s a binary build. Just give it the run flag with chmod a+x and when running it should display the current song in the top left corner (Provided you use dwm and a song is playing in mpd :P).


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