How to check when MPD changes track?

dmz · 2009-07-07 03:31:23

I want to log every time when MPD changes song, but I can't find out how. Anyone got any ideas?

BurntSushi · 2009-07-07 04:45:10

A hackish way might be to run a simple shell script to check the output of an mpd client (like mpc). If you're fine with assuming every song will be at least x seconds long, you could setup a simple while loop that sleeps x seconds, and checks if the output of mpc (or some other client) has changed since the last check (and make sure that it is playing a song). You could even change the sleep time dynamically based on how much time the song has left to play, if you're really concerned about CPU usage.

I'm not sure if there's anyway you could setup an event to fire within mpd, though.

Last edited by BurntSushi (2009-07-07 04:45:56)

dmz · 2009-07-07 05:03:46

Yeah I thought in the same way too... That's a damn ugly hack though. Maybe there's some other way...

koper · 2009-07-07 13:40:51

here is the code in C that prints out name of the song when mpd changes it.

#include <unistd.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <libmpd.h>
#include <debug_printf.h>
#define RED "\x1b[31;01m"
#define DARKRED "\x1b[31;06m"
#define RESET "\x1b[0m"
#define GREEN "\x1b[32;06m"
#define YELLOW "\x1b[33;06m"

void status_changed(MpdObj *mi, ChangedStatusType what)
{
        if(what&MPD_CST_SONGID)
        {
                mpd_Song *song = mpd_playlist_get_current_song(mi);
                if(song)
                {
                        printf(GREEN"Song:"RESET" %s - %s\n", song->artist, song->title);
                }
        }

}

int main()
{

        int run = 1, iport = 6600;
        char *hostname = getenv("MPD_HOST");
        char *port = getenv("MPD_PORT");
        char *password = getenv("MPD_PASSWORD");
        MpdObj *obj = NULL;


        if(!hostname) {
                hostname = "localhost";
        }
        if(port){
                iport = atoi(port);
        }

        obj = mpd_new(hostname, iport,password);

        mpd_signal_connect_status_changed(obj,(StatusChangedCallback)status_changed, NULL);
        mpd_set_connection_timeout(obj, 10);

        if(!mpd_connect(obj))
        {
                mpd_send_password(obj);
                do{
                       

                        mpd_status_update(obj);
                }while(!usleep(100000) &&  run);
        }
        return 1;
}

to compile it:

gcc source_code -o output_file -lmpd -I/usr/include/libmpd-1.0/libmpd/

the code it's actually a modified example from libmpd site:
https://svn.musicpd.org/MOVED/libmpd/tr … testcase.c

Last edited by koper (2009-07-07 13:45:55)

Rasi · 2009-07-07 15:55:12

does this use mpds idle protocol? because it should. Its the only way of getting information without polling.

dmz · 2009-07-07 17:57:20

Thanks koper!

GogglesGuy · 2009-07-07 19:22:38

koper wrote:

here is the code in C that prints out name of the song when mpd changes it.

#include <unistd.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <libmpd.h>
#include <debug_printf.h>
#define RED "\x1b[31;01m"
#define DARKRED "\x1b[31;06m"
#define RESET "\x1b[0m"
#define GREEN "\x1b[32;06m"
#define YELLOW "\x1b[33;06m"

void status_changed(MpdObj *mi, ChangedStatusType what)
{
        if(what&MPD_CST_SONGID)
        {
                mpd_Song *song = mpd_playlist_get_current_song(mi);
                if(song)
                {
                        printf(GREEN"Song:"RESET" %s - %s\n", song->artist, song->title);
                }
        }

}

int main()
{

        int run = 1, iport = 6600;
        char *hostname = getenv("MPD_HOST");
        char *port = getenv("MPD_PORT");
        char *password = getenv("MPD_PASSWORD");
        MpdObj *obj = NULL;


        if(!hostname) {
                hostname = "localhost";
        }
        if(port){
                iport = atoi(port);
        }

        obj = mpd_new(hostname, iport,password);

        mpd_signal_connect_status_changed(obj,(StatusChangedCallback)status_changed, NULL);
        mpd_set_connection_timeout(obj, 10);

        if(!mpd_connect(obj))
        {
                mpd_send_password(obj);
                do{
                       

                        mpd_status_update(obj);
                }while(!usleep(100000) &&  run);
        }
        return 1;
}

to compile it:

gcc source_code -o output_file -lmpd -I/usr/include/libmpd-1.0/libmpd/

the code it's actually a modified example from libmpd site:
https://svn.musicpd.org/MOVED/libmpd/tr … testcase.c

So this wakes up every 0.1 seconds....? there goes your battery life...

Rasi · 2009-07-08 11:03:35

mpc 0.16 supports the idle event.

#!/bin/bash
while : ; do
        mpc idle
        mpc current
done

This will show the word "player" on each time play/pause/stop/next/prev have succeeded.

Other printouts are "mixer (volume change) "output" (output device enabled/disabled) "options" (e.g. playback mode changed). "update" (database updating)

The above script in action:

carnager@freebox ~/mpc % ./mpc.sh
player
Pearl Jam - Gone
player ---> PAUSE EVENT
Pearl Jam - Gone
player ---> NEXT EVENT
Pearl Jam - Better Man

Last edited by Rasi (2009-07-08 21:18:26)

msdark · 2009-07-08 13:29:14

(Sorry for my english)

i was wrote a C program to show notifications when mpd change the playin song .. now the code is out of date, but maybe the code will help you

http://aur.archlinux.org/packages.php?ID=19986

The idea was very simple... the binary check for the state of mpd using the same algorithm of lastfmsubmitd

I hope this can help you

fflarex · 2009-07-08 14:58:33

@Rasi: While you're using the updated mpc, you should probably use 'mpc current' instead of piping it to head.

Rasi · 2009-07-08 21:18:12

fflarex wrote:

@Rasi: While you're using the updated mpc, you should probably use 'mpc current' instead of piping it to head.

ah cool.. didnt know that

Arch Linux

#1 2009-07-07 03:31:23

How to check when MPD changes track?

#2 2009-07-07 04:45:10

Re: How to check when MPD changes track?

#3 2009-07-07 05:03:46

Re: How to check when MPD changes track?

#4 2009-07-07 13:40:51

Re: How to check when MPD changes track?

#5 2009-07-07 15:55:12

Re: How to check when MPD changes track?

#6 2009-07-07 17:57:20

Re: How to check when MPD changes track?

#7 2009-07-07 19:22:38

Re: How to check when MPD changes track?

#8 2009-07-08 11:03:35

Re: How to check when MPD changes track?

#9 2009-07-08 13:29:14

Re: How to check when MPD changes track?

#10 2009-07-08 14:58:33

Re: How to check when MPD changes track?

#11 2009-07-08 21:18:12

Re: How to check when MPD changes track?

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