Usage of buttons
Opens song explorer.
Shows the list of songs that are in current list ( Album / Folder )
Changes the playback potsition to the head of the song.
Rewinds the track. Speed of the rewind could be changed in preferences.
Plays music.
Fast forwards the track. Speed of the fast forward could be changed in preferences.
Changes the track to next track
Changes a temporary mak( green mark
）to normal mark（ yellow mark 
）.Temporary mark is created every time you seeked by touching seek bar. Please change to normal mark if you want to save the position.
Changes the playback position to the position of previous mark. Temporary mark is ignored when the button pressed( This behavior could be changed by preferences).
Adds mark at the current playback position.
Removes mark that is at current playback position. ( If mark is at current playback position, Adding mark button is changed to this button )
Changes the playback position to the position of next mark. Temporary mark is ignored when the button pressed( This behavior could be changed by preferences).
Shows the speed and pitch control dialog. Upper text in the button ( x1.00 ) means the speed. Lower text in the button ( P:1±0 ) means the pitch. To show pitch control view, swipe left in the speed settings dialog.
Switches repeat mode. When
is shown, player playes same song repeatedly. When 
is shown, player plays whole album / folder / playlist repeatedly. 
Switches mark loop mode. In mark loop mode, player plays the range between previous mark and next mark repeatedly.
Switches single track play mode. In single track play mode, player stops after playing the track. In mark loop mode, player stops after playing the range.