Optical Disc Playback and Copying Problems

When attempting to play or copy optical discs, there are three areas of potential problems. One area of problems is international optical disc playback (audio CDs do not have this problem), another area is laser or disc damage, and the last area is copy protection.

International Playback Problem #1 : TV Formats

Although the different TV formats were already covered in the TV Broadcast Formats article, here is a quick recap. Take a look at the modified map below from Paul Schlyter’s Analog TV Broadcast Systems article [1]:

Thankfully, there are universal DVD and BD players that can play back both 50Hz and 59.94Hz encoded DVDs and BDs such as those sold from Oppo Digital.

International Playback Problem #2 : Region Codes

Even if you get a universal DVD or BD player that can play back 50Hz and 59.94Hz DVDs and BDs, there is still something else you have to worry about, which is region codes. Here is another map from Paul Schlyter’s Analog TV Broadcast Systems article [1]:

The map above shows the different DVD regions. By looking at this map, you can see that if you are an American traveling abroad, the only other “safe” country to buy a DVD from is Canada. Any DVD bought in any other country besides Canada will most likely not work in an American DVD player.

BD also uses regions, and these regions are pictured below [2]:

The green-blue region is Region A, the orange region is Region B, and the red region is Region C [2].

Finally, a DVD or BD does not have to use region coding. DVDs and BDs marked as all-region will play back in any DVD or BD player, provided the DVD or BD player is universal [3]. If the player is not universal, you will still be limited to 50Hz or 59.94Hz countries depending on where you live.

Laser or Disc Damage

The whole reason that optical discs are called optical is because they are read by a laser. CDs are read by an infrared laser, DVDs are read by a red laser, and BDs are read by a blue laser [4 page 4].

Since optical discs are read by lasers, two things must happen for an optical disc to be read correctly. First, the laser in the disc drive must be working correctly. Second, and most important, the disc itself must be in good condition. Should either one of these conditions not be met, you will get read errors, meaning part or even all of disc will be unreadable.

If you encounter laser or disc damage, the best thing to try first is to see if the disc can be read in another drive. If that doesn’t work, another possible option is to use the “Recover” option in a computer program such as CDCheck. Optical disc recovery takes extra steps to try to copy files that are not normally taken. However, if you get so many read errors that you end up having to resort to some sort of recovery option, many of the files you recover will likely have problems, with audio files missing most of their audio being a good example. The last option would be to try some sort of optical disc repair product.

Copying audio CDs makes for an interesting demonstration of laser or disc damage. When digital audio is stored on a CD in the audio CD format, the same precautionary measures are not taken when storing files on a CD in the data format. Although this creates more storage space on an audio CD, it also makes audio CDs more vulnerable to read errors than data CDs. To deal with this, CD players are designed to estimate the proper sound during read errors if needed [5]. Although this helps to prevents clicks and pops in the audio, it can also make it tricky to know whether or not a copy of an audio CD is really an exact duplicate of the original. Luckily, there are computer programs designed to help you verify whether or not you have an exact copy of an audio CD [6].

Copy Protection Basics

Technology designed to prevent copying is known as copy protection, which sometimes referred to as content protection. Copy protection generally falls into two categories: copy protection designed to prevent direct disc-to-disc copies, and copy protection designed to prevent copying over audio/video (AV) connections. Unfortunately, optical disc copy protection can cause playback problems.

Disc-to-Disc Copy Protection

Some audio CDs use copy protection, but copy protection is not a part of the official CD format. Therefore, while copy-protected CDs will usually play fine in stand-alone CD players, they may not play back properly in computers [7]. By contrast, because the DVD and BD formats were designed from the beginning with copy protection [8], copy-protected DVDs and BDs usually play just as well in a computer as they do in a stand-alone player.

Analog AV Connection Copy Protection

For analog AV connections, the most common copy protection is Analog Copy Protection (ACP). ACP affects only video [9], was created by Macrovision Corporation, and was first deployed in 1985 on the VHS version of the film The Cotton Club [10]. Since ACP was created by Macrovision Corporation, it is sometimes referred to simply as Macrovision. However, Macrovision Corporation changed its name to Macrovision Solutions Corporation on May 2, 2008 [11] and to Rovi Corporation on July 16, 2009 [12], so it is more accurate to use the term ACP.

From a playback perspective, the major problem with ACP is that it can prevent proper playback in the following situations [13 pages 4-5]:

if you have an optical disc player or TV subscription box connected to a VCR and then to your TV rather than connecting the optical disc player or TV subscription box directly to your TV
if you are connecting an optical disc player or TV subscription box to a TV/VCR combination product

If you are running your video signal through a VCR because your TV is an old TV with only a cable input, then trying another VCR you have at your house or buying a device called an "RF modulator" are workarounds to this problem.

Digital AV Connection Copy Protection

For digital AV connections, the major copy protection scheme used is High-bandwidth Digital Content Protection (HDCP). Most video recording products today do not have a digital video input, so one might assume that HDCP does not play much of a role in today's electronics. This, however, is far, far, from the case. This is because HDCP is designed not only to prevent unauthorized RECORDING of digital video but also to prevent unauthorized DISPLAY of video. What this effectively means is that if your display does not have HDCP-certified digital video inputs, you will not be able to use those digital video inputs for watching content in High-Definition (HD) from an HDCP-certified source device [14]. In extreme circumstances, you may not get a picture at all [15]. Using an analog connection, buying HDCP-certified devices, or using an HDFury or Monoprice HDMI-to-analog adapter can fix this problem.

Sources

1. Paul Schlyter. Analog TV Broadcast Systems. Jan. 6, 2001.

8. BD Key Characteristics. Blu-ray Disc Association.