Keith Folsom's Blog

I found and fixed a fairly nasty bug in Just Playlists, so I’m releasing a new version, even though the last one hasn’t been out long.

If you were on the playlist chooser screen, clicked on a playlist, and then happened to rotate your phone during the load, the save data for the last playlist you were using could have been corrupted, so that the next time you loaded it, it would have forgotten where you were and would ask if you wanted to shuffle it.  Also, if you exited and re-ran the program, it may have started without a playlist loaded, just like the first time you ran the program after installing it.  I’ve corrected both problems.

While I was at it, I also added a clickable link to this blog in the “About…” dialog box.

I’ve managed to shorten the time it takes to load the artwork and tag information as tracks change during continuous playback.  Most of the time, the track starts to play at almost the same time as the information loads on the screen and the seekbar resets to 0.  If you’re running other things on your phone or memory is short, it could affect the time things take to happen.  But, overall, it should work a lot better.

I also found a good way to enable long text lines to crawl across the screen, rather than just using ellipses to indicate some of the text has run off the screen.  I’ve implemented this wherever I could that made sense to me.

Beyond this, I found a few more bugs that could cause crashes or strange program behavior.  My favorite one was when my phone crashed and, after it restarted, Just Playlists thought that my playlist files had changed and started offering me the option to shuffle them.  As it turns out, sometimes the version of Android I have running on my phone seems to get confused about the time zone and sets file modification dates improperly.  Thus, Just Playlists sees the file as changed because of the new timestamp and offers to reload them from scratch.  To avoid this, I now store the playlist files’ MD5 checksums and only consider a file to have been changed if this changes.  Thus, the actual content of the file must change and not just its last modified timestamp.

As I stated in a previous post, the next enhancement to the program will be a playlist creator/editor.  This will probably be a bit of work, so the next update might not be for a while, unless I find or hear about a major bug in the current version.  I hope I can also roll out the playlist editor in increments, adding features over time.

Time for a new version of Just Playlists.  In this version, the “Show Database” option menu item is active.  It shows the contents of the program’s database, which is where information is saved about each playlist you’ve used.  There is one entry per playlist, with a variety of data saved that allows the program to start playing a playlist from where you left off the last time you used it.  You can delete an entry by long-clicking on it.  The only entry you can’t delete is the top one—which is the currently-loaded playlist.  Entries are sorted in descending order by the date they were last loaded.  The currently-loaded playlist’s entry is the first and the playlist you haven’t loaded in the longest time is at the bottom.  Deleting a playlist entry doesn’t delete the playlist file from your microSD card.  Thus, deleting any entry for a playlist is pretty much the same as setting it up to reload from scratch—after deleting the entry, the next time you load the playlist, you’ll be asked if you want to shuffle it or not and a new database entry will be created.

The only time may want to delete a playlist entry is if you have deleted the playlist M3U file from your microSD card.  Once you’ve done this, you’ll see that the database entry for that playlist will say “File not found” in yellow text for the “File mod time” database field of the entry.  There is no modification time because the file no longer exists.  Leaving the database entry in the database doesn’t hurt anything, but it’s nice not to have unused stuff cluttering up the database.  If you have a huge number of unused entries, it could slow down the program a bit, so this is another reason you may want to delete “orphaned” entries.

The new preference I’ve added allows you to tell the program not to display its icon in the notification bar when it isn’t actively playing a song.  This is how the default Android music player works.  I prefer having the notification icon showing whenever the program is running—just so I can get back to it from any screen.  If it bugs you to have it showing, unchecking the option in the “Preferences” screen will take care of it.

For the next version of the program, I’m going to see if I can speed up the load time of the album artwork and track information when the next track starts playing during a regular playback session.  Right now, it can take a second or more for the info to load after the new track starts playing.  After that, I’ll take a look at creating a built-in playlist creator/editor for the program.  I haven’t considered this a high priority, since it seems to me creating complex playlists is going to be cumbersome on the phone compared to doing it on a computer and then uploading.  But for quick, small playlists, it could be handy.

Though I don’t have the “Show Database” feature ready yet, I improved a couple things and fixed some bugs that make a release worth it.  The bugs may have caused crashes when you rapidly changed between playlists or used the “Show Playlist” menu item.  As to the improvements, first, if you use the “Show Playlist” menu item to see the contents of the current playlist, the current track will be highlighted in green text.  In 1.4.1, the track won’t be updated if you have the playlist screen open when the next song begins to play.  In 1.4.2, it will.  If you leave the playlist screen open, the currently-playing track will always be in green and at the top of the screen.

The other improvement is sort of a bug fix.  It’s actually more of a workaround for a problem with Android’s Java implementation.  When using Just Playlists, you may have had the track’s artwork not show up even though you have artwork embedded in the file.  This shouldn’t happen any longer—unless the artwork really isn’t there.

For the curious, here are the gory details.  I use Java’s getCanonicalPath() method to turn the track name read in from an M3U playlist file into a fully-qualified file path with all relative references resolved.  This is used as a lookup key for ID3 tag information in Android’s database of scanned media information.  But, there seems to be a bug in Android’s Java implementation such that every so often, the method will throw a NoSuchElementException.  This isn’t supposed to happen.  According to Google’s issue tracker, this is a known problem in Android 2.0 and will be fixed in a future release.  So, it may not be happening any longer in Android 2.0.1 and 2.1.  I’ve also seen it in version 1.6.  I’ve added a try/catch block that handles this exception and uses the un-resolved track name from the M3U file if need be.  The key derived from this isn’t guaranteed to be unique in the media database, but it most likely will be and so will retrieve the proper ID3 tag info—including the artwork for the track.

It’s time for another upgrade to the program.  Besides a few more small tweaks and fixes here and there, I’ve added a “Show Playlist” menu item to the main screen options menu (the one that appears when you press the “Menu” button”).  This will show the contents of the current playlist, in the current play order.  That is, if you chose to shuffle the list, it will be shown shuffled, with the currently playing track highlighted in green text.  The tracks are numbered in the order they’ll be played.  You can touch any track to start playing it.  And, if you touch and hold a track, a pop-up context menu will appear, with the ID3 tag information as the menu header.  The track information displayed in the list isn’t from the ID3 tags of the track files.  It’s taken from the playlist filename itself, with the track file’s name sans extension shown first, the directory it is in next, and the next directory level up shown after that.  I use this info instead of the tag info because it loads faster.  It’s also nice to be able to see the file names if you’re like me and name in “artist/album/tracknumber – trackname” fashion.  If you need to see the tag info for a track, just touch and hold for the pop-up info.

You’ll also notice a “Show Database” menu item.  Right now, it doesn’t do anything but display a “Coming Soon” informational message.  For the next release, this item will bring up a display of all the saved information for each playlist you’ve played.  It will also allow you to delete any of the saved entries.  This is particularly handy for cleaning out old entries for which there are no longer playlist files on your microSD card.  The entries don’t take much space in the program’s internal database, so if you never use this feature, it’s not a big deal and won’t affect Just Playlist’s performance.  But this gives you control of a previously-hidden part of the program, which is almost always a good thing.

I’ve added a couple things to Just Playlists.  I debated holding off on releasing them until I get some more substantial work done on the program, but these are fairly useful additions.

First, I renamed the “Touch” item in the options menu to “Reload”.  Now, rather than just updating the current playlist for later reloading, you can choose to reload the playlist immediately.  For Just Playlists, a “reload” means reading the playlist in from the microSD card as if this is the first time the program has seen it.  You will be given the option to shuffle the playlist, and the saved track position will be deleted.  Also, the idea of touching a file is a Unix-y thing that may confuse a lot of people.

The second addition is context menus in the playlist load screen.  This means you can press and hold on a playlist name and see a pop-up menu.  This menu allows you to choose to either load the playlist to where you left off last time you used it, or you can choose to reload the playlist from scratch, without using the saved position information from the last time you used the playlist.  The load option is identical to simply touching the playlist name, which works the same as previously.

One last change was made due to feedback from a program user (thanks Eric!).  The music file names in your playlist files can now use either forward slashes or back slashes between each element in the filename’s path.  In the past, you could only use forward slashes.  This may be helpful if you export M3U playlists out of Windows Media Player, which uses back slashes.

I’ve upgraded Just Playlists—up to version 1.2.0 now.  I did some behind-the-scenes stuff to make it behave better, but the major thing is the addition of the ability to enable control of the player via your Bluetooth headset’s music control buttons.  The technical parlance for this is that you can now take advantage of Bluetooth’s AVRCP (Audio/Video Remote Control Profile).  If you have a Bluetooth headset that allows you to listen to music, it probably also has buttons for play/pause, next track, and previous track.  If you go into the preferences for Just Playlists, you can choose to enable these controls for use with the program.  The default is disabled.

It’s important to understand a little bit more about how Android handles Bluetooth headset buttons.  If you don’t have any other music player on your phone, the default Android music player program will receive headset button pushes, starting up if you push the play button and so on.  Other music playing programs that you download from the Market that can use Bluetooth headset controls should have a preference setting to enable/disable their ability to receive these button pushes.  Thus, if you enable another program to receive them, the default music program should no longer respond when you push a headset music control button.  If you enable more than one program to use the controls, you may have the wrong program respond to a button push.  Thus, I’d recommend only enabling one program at a time to receive these button pushes—and disable all of them if you want the default music player to respond.

If you enable Just Playlists to respond to button pushes, it won’t start playing when you push a button unless it is already running.  I decided I don’t like a music program starting up on its own if I accidently hit one of the control buttons.  Once you’ve explicitly started Just Playlists, it will respond.

Once again, my only Android hardware is a G1, so if you use the Bluetooth control stuff on another type of phone and it doesn’t work as described, let me know.

I’ve finished work on the second iteration of Just Playlists—version 1.1.2.  Here’s a summary of the improvements and fixes:

• Added a “Preferences” menu item, which opens a standard Android preferences screen.  Look here for new features that can be enabled and disabled.
• The current track’s position index in the playlist and the total number of tracks in the playlist can be displayed next to the playlist name on the main screen.  The default is not to show this.
• Choose to have a playlist stop playing when the last song is reached or loop back and start over at the first track in the playlist.  The previous version repeated.  The default in the new version is to stop.
• Fixed various crashes and inconsistent program behavior when the screen was rotated during loading of playlists while transitioning between screens.
• When the program starts, the loading progress message box will appear.
• If the last playlist to be loaded before the program is closed is changed, you’ll be given to opportunity to shuffle it when the program starts and re-loads this playlist.

I’ll continue adding the other features I mentioned in my previous post about the program, as well as a few other things that I think will be useful.  My first priority will be to fix any other bugs I find and to clean up the code as I find better ways to do things under Android.  The next new features will probably be the ability to look at the music tracks in the current playlist and Bluetooth headset control.