Why won't iTunes sync my music to iDevices? Difficulty level: Aneurysm.

• Why won't my music sync and play properly?! I have been struggling with this since iOS 5? 6? Feels like forever - I am so beyond frustrated. So much so that I am ready to just stop using music on my iPhone and iPad completely. Which was the reason I got an iPhone in the first place. History: I've been using iTunes with iPods, iPhones and iPads since 2005. So I know how syncing is *supposed* to work. This didn't used to be a problem! I have a mixed library of about 30gig of music, accumulated across many years. I have a smart playlist which randomly picks about 10g of music. I would like to sync this to my iDevices. I have a personal iPhone 5, a work iPhone 5S, a third gen iPad and a latest gen iPad mini. I have a single iTunes library and a single iTunes/iCloud account. All are logged into the same account and I have only ever used the devices on a single account. THE PROBLEM: no matter how I sync, about 30% of music either -doesn't play (iPhone or iPad will either quickly skip to next song or just silently stall at 00:00) -OR will play partway through and then abruptly skip to next -OR sound garbled like an old tape cassette being chewed. This does not happen when played in iTunes on my laptop. The music is not corrupted, nor is the library. This happens with both iTunes purchased AAC and other-sourced MP3s. This has happened with devices restored from backup and new devices. This happens with iPhones and iPads, both new and used. The only device this has not happened with is my work phone - because I've never synced it with iTunes. THINGS I HAVE TRIED: -Syncing over wifi -tethered syncing -Manually managing -Syncing to "empty" my music, then resyncing -deleting suspect songs from library and redownloading from itunes, then resyncing -as above, but on iPhone/iPad (this often results in duplicates and/or "ghost" tracks which aren't actually there) -restoring from backup -rebuilding playlist -turning iCloud on/off -converting MP3 tracks to AAC -downloading past purchases to phone via iCloud and then syncing -nearly every "solution" I've been able to google THINGS I DON'T WANT TO DO: -abandon iDevices -streaming services Please, please, please help. I'm at the end of my tether. My iPad mini is new, and I had hoped that it would Just Work as it's supposed to. But I've spent all day with duplicate tracks, ghost tracks, incorrect syncing, and frayed nerves. I dream of being able to just sync a single random playlist over wifi at night so I can go to work in the morning with some new tunes and a smile. If the hivemind can't solve this, then all hope is truly lost.

• Answer:

  Usually when I see problems like this it's because the decoder on iOS supports a different subset of decoding options than the desktop machine. In other words, you need to narrow down which tracks are problematic, and re-encode them with iTunes. If you have any codecs on the host machine which might be taking over, you'll need to disable them when you do this re-encode. This was especially apparent on video recently, when there were Quicktime Components like XVID and DIVX which were silently taking over MPEG-4 or H.264 encoding, and generating files which iOS didn't like at all. The same thing applies to music files though - if your encoder (in the past, perhaps) generated marginally compliant files, iOS will have more problems with them than your desktop machine because you can install a wide variety of codecs on desktop operating systems, but not on iOS.