Ripping is the process of copying audio or video content to a hard disk, typically from removable media. The word is used to refer to all forms of media. Despite the name, neither the media nor the data in it is damaged after extraction.
Digital audio extraction is a more formal phrase applied to the ripping of audio CDs. Ripping is distinct from simple file copying, in which the source audio/video is not formatted for ease of use in a computer filesystem. For example, the hierarchy of files making up the audio/video data on a DVD-Video disc can be encoded into a single AVI file. In addition, the copied data are often compressed with appropriate codecs. Ripping is often used to shift formats, and to edit, duplicate or back up media content. Media files released on the Internet may describe the source of the rip in their names, e.g.
A CD ripper, CD grabber or CD extractor is a piece of software designed to extract or "rip" raw digital audio (in format commonly called CDDA) from a compact disc to a file or other output. Some all-in-one ripping programs can simplify the entire process by ripping and burning the audio to disc in one step, possibly re-encoding the audio on-the-fly in the process.
On the whole, it is legal for an individual in the United States to make a copy of media he/she owns for his/her own personal use. For instance, making a copy of a personally-owned audio CD for transfer to an MP3 player for that person's personal use would be legal.
In the case where media contents are protected using some effective copy protection scheme, the Digital Millennium Copyright Act makes it illegal to circumvent that copy protection scheme. This law makes it illegal to rip most commercial DVDs as they are typically protected by CSS encryption.
There are also legal restrictions on what may be done with rips. As made clear above, ripping unencrypted media for personal use is legal. However, it is often the case that ripped music and videos are not ripped solely for personal use but are distributed to others. Unless this distribution is covered by the limited fair use exceptions to copyright law, then this constitutes an offense under U.S. copyright law as distribution is one of the exclusive rights granted to copyright holders. This is regardless of whether the distribution is commercial or free of charge.
Recording industry representatives have claimed (in the context of Atlantic v. Howell) that ripping itself may be regarded as copyright infringement. However, there is no legal precedent for this and, even within the industry, this is the minority view. In oral arguments before the Supreme Court in MGM Studios, Inc. v. Grokster, Ltd., Don Verrilli, representing MGM stated: "And let me clarify something I think is unclear from the amicus briefs. The record companies, my clients, have said, for some time now, and it's been on their Website for some time now, that it's perfectly lawful to take a CD that you've purchased, upload it onto your computer, put it onto your iPod. There is a very, very significant lawful commercial use for that device, going forward."
In countries such as Spain, anyone is allowed to make a private copy of a copyrighted material for oneself, and the source copy does not even have to be legal. Making copies for other people, however, is forbidden if done for profit. This is also true for Sweden.
In the United Kingdom, making a private copy of copyrighted media without the copyright owner's consent is illegal: this includes ripping music from a CD to a computer or digital music player. The UK government has made proposals to allow people to make copies of music for personal use.. According to one survey, 55% of British consumers believed ripping a CD to be legal, and 59% admitted to doing it..
CD audio has two major design constraints that make it difficult to obtain accurate copies in the form of a standard digital file. First, the system is designed to provide audio in real time in order to ensure continuous playback without gaps. For this reason, it does not provide a reliable stream of data from the disc to the computer.
Secondly, the designers felt that it would be preferable for major scratches in the disc to be covered up rather than resulting in total failure. Normally, an error correction system such as Reed Solomon would provide either a perfect copy of the original error-free data, or no result at all. However, CD audio's Cross-interleaved Reed-Solomon coding includes an extra facility that interpolates across uncorrectable errors. This means that the data read from an audio CD may not in fact be a faithful reproduction of the original.
Another practical factor in obtaining faithful copies of the music data is that different CD drives have widely varying quality for reading audio. Some drives such as Plextor are thought to deliver extremely accurate copies while others may do little or no error correction and even misreport error correction information.
There is specialized software that will attempt to correct errors, and also attempt to report if errors could not be corrected. They use a variety of techniques, such as making use of error correction information, knowledge of the peculiarities of different drives, and ripping multiple times and comparing the results. All of these programs are still susceptible to some degree to poor CD drives.
Over the years a variety of companies that offer ripping services to consumers have entered into the market. Services utilize quality equipment and processes to ensure an accurate extraction of audio. Some services offer commercial disc resurfacing to remove scratches that can cause some of the audio extraction anomalies inherent in the audio CD format.