Quick Tip: Suffering Individual Disc Playback Freezes? Clean The Disc!

When you try to play your latest, smash hit, movie disc, does your player "freeze up" part way through?  Does this always seem to happen just as the movie gets to the GOOD part?  Does it then ignore all your desperate efforts to get it playing again?

And are your friends and family now judging you; given all the money you've spent on your Home Theater system, only to have THIS happen?

Is that your problem, Bunky?

Well take heart old chum!  Your problem may have an easy fix:  Clean The Disc!

Optical Digital disc players have come a LONG way from the days of the first CD players.  I've been at this long enough to recall a time when playing a CD required EVERYONE in the room to sit down quietly and remain motionless.  No, not to hear the music better, but because ANY vibration in the room would cause the optical disc player to SKIP!

What's changed is the optical drives in newer players have gotten a LOT smarter about Error Correction and Disc Read Error Recovery.  Nevertheless, the tolerances involved in correct playback of these discs are very tight indeed.  And never more so than with the new, UHD (4K) movie discs!

Curiously, the things you'd THINK would cause most of the problems generally do NOT cause problems (or perhaps, only relatively minor playback glitches) in modern players.  Common, visible scratches?  No problem.  A complete set of fingerprints, along with a partial palm print?  Not hard enough!

(With rental discs, such fingerprints can even provide a fun, historical record of who's played the disc before you -- if you are of an, umm, forensic turn of mind!)

OK, if your kids leave peanut butter and jelly on the disc's playing surface, that WILL probably screw things up.  But the reality is, the Error Correction and Disc Read Error Recovery software built into modern disc players really does work surprisingly well in the face of the most common problems.

The first line of defense -- the automatic, data Error Correction in the optical drive -- uses clues built into the disc's authoring format, and is designed to play through common problems; reconstructing "correct" data on the fly, DESPITE such problems.  So in most cases you'll never even know correction is happening.  For example, the most common cases of fingerprints on the playing surface will NOT cause playback problems.  Error Correction is THAT good!

What DOES give the player fits is problems on the disc's playing surface which span a longer, continuous run of playing time.  That would include scratches that run AROUND the disc in a circular shape -- rather than straight out from the center towards the edge or more at an angle.  And it also includes any sort of "film" over the playing surface.

Such issues produce data read errors which go BEYOND what the automatic data Error Correction can handle.  And so the player reverts to its next line of defense:  Disc Read Error Recovery.  This simply means the player pauses normal playback and starts scanning forward trying to find the next portion of the disc it CAN read.  If the issue causing the problem on the disc spans a significant range of playing time, Disc Read Error Recovery can take a while!  The player likely encounters multiple portions it can ALMOST read, but then has to give up and keep scanning.

Note that the player is not playing the disc "normally" while this is happening.  So the normal playback navigation functions in the player can not work -- things like Fast Forward or Chapter Forward will be blocked.  If the player has a display showing the timecode of playback, that too will likely appear frozen, or will advance only in jumps.  This is all happening at a very low level in the player's firmware, which means other portions of the "user interface" are also blocked.

All this is what gives the appearance the player has Crashed -- i.e., has become unresponsive. If you are patient long enough, the player will either find a place to start playback again, or it will reach the end of the disc and just Stop the disc.  That is, the player, most likely, is NOT really Crashed; just very tied up at the moment.  However, this is cold comfort when you still can't watch the remaining part of your movie!

There's not much you can do about a disc that's been scratched in a way which triggers Disc Read Error Recovery.  But if you've got a "film" on the playing surface, that IS something you can correct!

TECHNICAL NOTE:  There's been a substantial increase in unplayable disc reports over the past couple years related to UHD (4K) discs.  Partly this is due to the fact the tolerances for this new disc format are even tighter than for prior discs.  But in addition, it has become clear some of these discs are getting into retail still with a "film" over the playing surface which should have been removed during the last steps of manufacture.  This is, evidently, the non-stick coating which keeps a stack of these discs from sticking together in the manufacturing equipment.  This is a uniform, almost completely transparent film -- which means it is NOT VISIBLE to the naked eye.  Since it covers the entire playing surface, it causes real problems whenever the player first encounters a read error at the limits of what automatic data Error Correction can handle.  That's because Disc Read Error Recovery -- the next line of defense -- can ALMOST read large swathes of the rest of the disc!  Meaning it keeps trying -- and trying.  And again, this extended effort to find a portion that CAN be played is what makes the player appear to be Crashed.  Fortunately, it is EASY to remove this leftover manufacturing film -- see the Clean The Disc steps below.

First let's do some Differential Diagnosis.  * "House" theme music starts to play *

The sort of problem I'm discussing in this post refers to issues with INDIVIDUAL discs.  If you are having problems with LOTS of your discs, then there is something else going on.

The "something else" is most often that a bit of lint, or an oily film, has blocked the lens of the laser which reads the disc.  The fix for this is to Clean The Lens.  For lint, that can often be done by opening the tray and spritzing with a can of clean compressed air (i.e., the type sold in camera stores for cleaning camera lenses) into the player towards the top of the lens assembly.  If you've got an oily film on the lens (as from tobacco smoke, cooking smoke, scented candles, or artificial fireplace logs), the correct solution is to open the player to access the lens assembly and gently clean the lens with a Q-tip dampened with some rubbing alcohol.  (If you are not of a temperament to open up your electronics for such stuff, a repair shop can do this for you.)

The lens assembly in the optical drive is underneath where the disc sits, and points upwards towards the playing surface of the disc.  There are actually TWO lenses in the assembly for modern Blu-ray and UHD disc players.  One is for the Blue laser which is used for playing Blu-ray and UHD discs, and the other is for the Red laser which is used for playing SD-DVD, CD, SACD, and DVD-Audio discs.  Indeed a key symptom indicating a dirty lens problem would be the player has problems with multiple Blu-ray discs, but plays SD-DVD discs just fine (indicating the Blue laser lens is dirty), or vice versa (indicating the Red laser lens is dirty).

Again, dirty lens problems would be your initial diagnosis if LOTS of your discs are having playback problems.

Next, there ARE such things as "manufacturing flaws" in commercial discs.  That is, if a disc won't play, it may be part of a "bad batch" of discs.  Movie studios use multiple disc production facilities to make their discs.  Often more than one production line for any given title.  And sometimes a run of discs from one production line will just be flawed.  These flaws are usually *NOT* visible to the naked eye:  For example, if the center hole of the disc is slightly OFF center, or if the the disc thickness is out of tolerance, or if the process for putting the data on the disc was slightly out of calibration.  Such "bad batch" production runs are more common than you'd imagine, despite the quality checks during manufacture.

Frequently, but not always, you can find reports on-line indicating a bad batch is out there for some popular disc.  But the simpler approach is this:  If you have a problem with an individual disc which is *NOT* easily cured by the Clean The Disc approach described below, just ASSUME it is from a bad batch.  Take it back to where you got it and exchange it.  If for some reason you can't do that, it is often the case the Studio will swap out a disc for you if asked.  Finding Contact info for Customer Service at most Studios is pretty easy on-line.

Clean The Disc

Just in case it isn't obvious to you, the "playing surface" of your optical disc is the shiny side of the disc.  The side which does NOT have the advertising label on it!  The side which faces DOWN when you play the disc.  In the world of SD-DVD discs, you may also encounter discs which are shiny on BOTH sides -- i.e., no label on either side.  (Flip the disc to play the alternate side.)  In such cases, the side facing DOWN when you have the playback problem is the side you need to clean.

WARNING!  * "House" theme music starts to play agin *  First Do No Harm!  You can damage the playing surface of the disc if you are cavalier in cleaning it.  Blu-ray and UHD discs have a tougher playing surface -- less subject to scratching -- than SD-DVD, CD, and other music discs.  However even these newer types of discs can still be scratched.  And again, the most problematic scratches are ones that run in a circular path around the center hole -- more so than scratches which run radially between the center hole and the edge of the disc.  So the rules for cleaning are:

  1. Wash your hands first.  Dirt on your hands can be abrasive.
  2. Be gentle.  If the stuff you are trying to remove does not come off with gentle rubbing then the disc is likely beyond repair.
  3. Do not use abrasive material to wipe the disc.  Best is a "micro-fiber" cloth or a clean, cotton towel.  Do not use paper towels as the wood fibers in the "paper" can be abrasive.
  4. Do not use "solvents".  Wipe with a dry cloth, or clean with warm tap water and some dish soap.
  5. Always wipe in a RADIAL direction -- back and forth between the center hole and the edge, shifting your wiping location to cover all the way around the disc.  Do NOT wipe in a CIRCULAR direction AROUND the center hole.  This really only matters if you leave a scratch behind -- i.e., circular wiping is not automatically going to ruin your disc!  But if you DO leave a scratch behind, circular scratches are far more problematic than radial scratches, so play it safe!

If your problem is from that manufacturing "film" mistakenly left on a brand new UHD disc, as described above, simply wiping the disc with a dry, micro-fiber cloth may be all that's required.

In a more stubborn case -- such as also wanting to remove oily fingerprints -- or peanut butter and jelly -- let hot tap water run across the playing surface of the disc for a bit BEFORE you do any wiping.  The idea is to sluice off any particles which might scratch the disc before you start to wipe.  Then clean with warm tap water and dish soap -- wiping as described above.

Then put the disc on a clean, dry cotton towel -- with the playing surface facing up -- and pat dry the playing surface with another clean cotton towel or micro-fiber cloth.  Turn over and do the same with the label surface.  Turn the playing surface face up again and let it sit for a minute or so to further air dry before putting the disc back into the player.

While you are waiting, examine the playing surface by angling it under a strong light to look for scratches or any other cruft still left on the surface.  Scratches may give you a clue where playback problems might still crop up.  But again, automatic data Error Correction usually handles scratches so well you'll never even notice.  If there is still cruft on the playing surface, try another cleaning pass.

That's it!

Again, if you continue to have problems DESPITE having done a Clean The Disc pass, then the odds are you have a disc from a bad batch.  Try to exchange it.  Although it is possible there's a firmware flaw in your player which keeps a specific disc title from playing properly, it is much more likely the disc itself has a manufacturing flaw.

And of course, be careful how you handle your discs, so you don't mess up the playing surface yourself -- or, umm, leave fingerprints behind for future stalkers to find!