audio_file_player offers a simple way to play audio files through an action server interface and a topic interface.

By default it uses sox's play to play the audio files (as it plays more file types than for example aplay). You may need to install:

sudo apt-get install sox libsox-fmt-all

You can find an example mp3 file in this package in the folder assets, called tada.mp3.

Launch the node:

roslaunch audio_file_player audio_file_player.launch

Try the topic interface:

rostopic pub /audio_file_player/play std_msgs/String `rospack find audio_file_player`/assets/tada.mp3

Try the actionlib interface:

rosrun actionlib axclient.py /audio_file_player

If you want to use your own command for playing the files (or even use this node for some other purpose) just modify the launch file to use the command and flags that you want:

<launch>
    <node pkg="audio_file_player" name="audio_file_player" type="play_file_server.py" output="screen">
        <!-- Parameters to change the player to use other commands, flags and the rate (Hz) at which
        the feedback is published, this is equivalent to the default configuration -->
        <param name="command" value="play"/>
        <param name="flags" value=""/>
        <param name="feedback_rate" value="10"/>
    </node>
</launch>

You have a tiny node to get and set the volume via a std_msgs/Int8 topic (values 0-100 representing the percentage of volume) in the scripts folder with it's launch file:

roslaunch audio_file_player volume_manager.launch

By default the topics are:

    /volume_manager/get_volume
    /volume_manager/set_volume