CD-DA, that is, music CDs, commonly known as CD records, is the most widely used CD and one of the most pirated CDs. In order to protect copyright, record companies have adopted anti-copy technology to prevent piracy. International federation of the phonographic industry (IFPI) held high the banner of protecting the intellectual property rights of music and launched a worldwide struggle against piracy. IFPI also specially designed two sets of logos for anti-copy discs. The icon is composed of two black and white circles and triangles, which contrast the two characters "C" and highlight the theme of "Copy Control".
Anti-copy technology has been used for music CDs for a long time, but in the past, due to technical reasons, the effect was not satisfactory. At present, CCCD adopts the "Cactus Data Shield" (CDS) technology of Israeli security company Midbar.
there are three versions of CDs: CDS-1, CDS-2 and CDS-3.
CDS-1
can be used in a standard music player, but it is forbidden to be used on a PC. Nor can it be used on portable playback devices, unless special CDs made for the portable playback devices are bundled together.
CDS-2
This is the most widely used CDS technology at present. CD-ROM can be used in a standard music player. Music files are allowed to be played on a PC through a dedicated player attached to the CD-ROM, but copying files to the hard disk of the PC is prohibited.
CDS-3
CDS-3 is jointly developed by Midbar and Macrovision, and released by the latter. CDS-3 solves the contradiction between copy prevention and CD universality. From the point of view of preventing copying, obstacles are still set up for the music section that conforms to the red book in the CD. However, music can be played through Microsoft media player on PC. Users can copy music files to Windows Media Library to play without the original CD. Music files cannot be played if they are distributed on the Internet or sent by Email. The compressed files and supporting programs of CCCD CD only use 5~1% of the capacity of the CD, and 67 minutes of music can still be put in a 74-minute CD. Support and protect multimedia CD content, including: music, movies, pictures, text and so on. Consumers do not need to attach additional devices. Compatible with all "SCMS", "watermark" and "fingerprint technology".
CDS technology is strictly confidential. Record companies must get permission to publish CCCD, and even optical disc companies that make the master must get permission to produce it. And getting a license to use CDS technology must pay a lot of money.
now let's analyze CCCD from a technical point of view. Strictly speaking, CCCD is not a CD-DA in redbook format. The following figure shows the CCCD track structure made by CDS-2 technology.
the CD has two Sessions, and the first session stores 15 songs, which is completely made according to the CD-DA format. Some people have worried about whether CCCD will affect the sound quality. In fact, this kind of worry is completely unnecessary, because CCCD's processing of music resources is completely carried out according to CD-DA mode. The second section is similar to a data disc, which has a directory structure. PLAYER.EXE is the special player for this CD. Comparing the track structure of CCCD with the track structure of a typical CD format optical disc, we can see that it is a CD-Extra optical disc rather than a CD-DA. However, it is different from CD-Extra. The standard CD-Extra disc can display all files in two sections of the computer, but CCCD is not. In fact, the secret is in the second section! The standard CD player reads the first section first, so it can play all the songs in this CD normally. The PC reads the last section, the second section. The CDS technology is to disguise the music file in the first section as the control symbol of the CD, so that the computer can't find the music file. Therefore, only the directory of the second section can be seen on the PC to achieve the purpose of copy prevention.
the current CCCD adopts CDS-2 technology, which can be played on PC. Although the CD can't be recognized by Windows Media Player, it can still be played normally by using its own playback software. The specific usage method is as follows:
Insert the CD into the optical drive. If the optical drive is set to play automatically, a player will appear on the desktop (Note: CCCD of different programs may have different shapes, but the functions are the same. See the picture below) and start playing the first music (song) automatically.
if the CD-ROM drive is not set to play automatically, or if it is not played automatically, run the player.exe program in the root directory of the CD-ROM or play it.
There are three buttons on the right side of this player. The button labeled "PL" below can open the track menu of this CD.
at this time, the player automatically plays the first song of the CD. If you want to listen to other songs, just use the mouse to select them and double-click them.