James's Weblog

A lot of audio players like to combine Play and Pause buttons. If a song is playing, pressing the Play button again pauses the track; if a song is paused, pressing the Play button resumes playing. It makes sense and reduces the number of buttons, right?

Winamp does not take this approach, and I commend its developers for it.

On the surface, combining these two buttons seems like a great idea. However, let’s suppose you want to replay the current track. Maybe you’re not paying attention and suddenly realize that the song you’re listening to is a favorite that you haven’t heard in a while, or maybe you’re just in the mood to listen to a particular song over and over.

In Winamp’s separate button design, if a song is playing, pressing the Play button again re-plays the current track. In the combined button design, pressing the Previous Track button typically returns to the track’s beginning. Seems like a sound design so far.

Now let’s suppose you want to skip to the previous track. In the separate button design, the Previous Track button always selects the previous track. In the combined button design, however, the Previous Track button only sometimes selects the previous track, since it’s also used to restart the current track. Typically the button skips to the previous track only if it’s already at the beginning to another track—the “beginning” defined as some arbitrary number of seconds.

Thus, overloading the Play button with pausing functions means we need to overload the Previous Track button too. Furthermore, overloading the Previous Track button requires introducing either time-dependent behavior or button modality. That’s a significant increase in interface complexity to save a single button. (The Previous Track and Next Track buttons typically have another behavior too; they seek within tracks when the buttons are held down.)

Increasing interface complexity increases error rates. My car stereo uses the combined button approach, and it makes it difficult for me to navigate backwards through CD tracks when I want to find a particular track. I need to listen for a few seconds to determine which track is which, and depending on how long I wait to listen, I sometimes need to press the Previous Track button once and sometimes twice. This is even more problematic when I’m driving and not looking at the track number.

Makers of software-based audio players have nothing to lose by providing separate buttons; virtual buttons have no monetary cost. Makers of car stereos should provide separate buttons because it’s a little safer.

(Although I prefer separate buttons, if space is at a premium, a respectable compromise might be to combine the Pause and Stop buttons instead. If pressed briefly, pause; if held down, stop. If the Stop button has been done away with too, then perhaps holding down the Play button can replay the current track.)