October 22 '12 - 12:16 pm

Find Truncated Tracks

So there’s this problem with iTunes Match whereby a downloaded file is unable to be played all the way through. My friend Kirk McElhearn describes the problem in great detail here. Essentially, the iTunes Match file is downloaded but some kind of corruption in the file prevents audio data from being read/played all the way through to the end even though all the data is very likely extant. If a truncated track and associated file are deleted it can be re-downloaded intact successfully. But it is difficult to hunt these tracks down since the reported duration, start, finish, size and time values of the tracks are correct and there is otherwise nothing detectably unusual about them.

The only way to discover if a track is truncated is to play it and hear it end abruptly. Since it appears that less than half the audio data of these tracks is playable, I found that by starting to play the track after positioning the cursor very close to the end of the track in the iTunes LED window the next track would play immediately if the clicked-on track was truncated.

So I’ve written a script, Find Truncated Tracks, that automates this process for a playlist of tracks and copies the varmints to a discrete playlist for later recycling. Find Truncated Tracks will go through the tracks in the current playlist starting with a single selected track. It will position the play head at ten seconds from the end of the track. Then, it will play the track and immediately check the player position. If the track is truncated, the player position will be the last playable second of the track which will be much sooner than the ten-seconds-from-the-end play position at which the track was just set to start. Thus detected, this truncated track will be copied to a new playlist named “_Truncated Tracks”. And so on for each track in the playlist from the selected starting track.

Unfortunately, it’s not terrifically fast. Each track must be played in real time so that the script can detect if it can play all the way through. Fortunately, a track only needs to play for a fraction of a second to get its current player position. But still, the script’s not going to finish up instantaneously. Average running times at my house were about three minutes per thousand tracks.

Play counts are not affected.

You may run into a dialog that will popup for unauthorized purchased tracks (if you have any of those). AppleScript can’t prevent this, so that may put the kibosh on unattended use. Otherwise, just let it run and go out for a sandwich.

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