In the history of optical storage media there have been and there are different optical disc formats with different data writing/reading speeds.
Original CD-ROM drives could read data at about 150 kB/s, 1ÃÂ constant angular velocity (CAV), the same speed of compact disc players without buffering. As faster drives were released, the write speeds and read speeds for optical discs were multiplied by manufacturers, far exceeding the drive speeds originally released onto the market. In order to market increasing drive speeds, manufacturers used the symbol nÃÂ, whereby n is the multiple of the original speed. For example, writing to a CD at 8ÃÂ will be twice as fast as writing onto a disc at 4ÃÂ.
There are two main types of disc speed, which are the angular and linear velocities. If the disc spins at a constant angular velocity, the linear velocity is 2.4 times higher at the outer edge.
Modern compact discs support a writing speed of 52ÃÂ and higher, with some modern DVDs supporting speeds of up to 24ÃÂ. Writing a DVD at 1ÃÂ () is approximately 9 times faster than writing a CD at 1ÃÂ (). However, the actual speeds depend on the type of data being written to the disc.
For Blu-ray discs, 1ÃÂ speed is defined as 36 megabits per second (Mbit/s), which is equal to 4.5 megabytes per second (MB/s). However, as the minimum required data transfer rate for Blu-ray movie discs is 54 Mbit/s, the minimum speed for a Blu-ray drive intended for commercial movie playback should be 2ÃÂ. The fastest Blu-ray speed is 16ÃÂ. For CDs, the 1ÃÂ writing speed is equivalent to the 1ÃÂ reading speed, which in turn represents the speed at which a piece of media can be read in its entirety, 74 minutes. Those 74 minutes come from the maximum playtime that the Red Book (audio CD standard) specifies for a digital audio CD (CD-DA); although now, most recordable CDs can hold 80 minutes worth of data. The DVD and Blu-ray discs hold a higher capacity of data, so reading or writing those discs in the same 74-minute time-frame requires a higher data transfer rate. Drive speed can be limited intentionally to reduce noise from the drive or slow down ripping, such as the firmware component Riplock.
Since their introduction on various optical storage media from the fifth to the sixth generation (1994âÂÂ2005), video games typically did not require installation on non-optical storage, as the reading speeds of optical drives were sufficient for direct data access from discs. However, with the advent of seventh generation video games, the increasing size of data and the demand for higher-quality texture mapping highlighted a growing disparity between design and graphics requirements and the technological limitations of optical storage's reading speeds and transfer rates.
PlayStation 3 video games were stored on single-layer 25 GB Blu-ray discs. However, like most early Blu-Ray devices the console's optical drive operated at a speed of 2à(9 MB/s). In contrast, the Xbox 360 utilized dual-layer DVDs with a formatted capacity of 7.3/8.3 GB (XDG2/3 format, respectively), and its optical drive ran at a 12àspeed multiplier (16.5 MB/s maximum). This meant that the Xbox 360 could deliver data transfer rates up to approximately 85% faster than the PlayStation 3. The slower transfer rate of the PlayStation 3 often prompted multi-platform developers to require a mandatory installation of a portion of the gameâÂÂs content onto the console's hard disk drive (HDD) to mitigate issues like longer loading times. The Xbox 360 (and, later, the PlayStation 3) allowed users to install games completely on the hard drive, which could enhance loading times; however, this feature was not mandatory. Optical discs were still necessary to launch games. During the seventh generation of gaming, it was uncommon for titles to fill the entire 25 GB capacity of a single-layer Blu-ray disc. Likewise, very few titles required multiple DVDs on the Xbox 360.
Starting with the eighth generation of video game consoles, the demand for full 1080p high-definition video and higher quality textures necessitated a greater data transfer rate. Contemporary Blu-ray optical drives, which operated at a reading speed of 6ÃÂ (approximately 27 MB/s) quickly became inadequate for these requirements. As a result, consoles like the PlayStation 4 required video games to be fully installed on the hard drive, enabling a higher data transfer rate. Similar to the Xbox 360, optical discs were still necessary to launch the games.
Almost all modern CD/DVD-burning software supports a selection of speeds at which the writable disc can be written. However, the option a user chooses only defines the theoretical maximum of disc burning process. There are other factors that influence the time taken for a disc to be written to:
A higher writing speed results in a faster disc burn, but the optical quality may be lower (i.e. the disc is less reflective). If the reflectivity is too low for the disc to be read accurately, some parts may be skipped or it may result in unwanted audio artifacts such as squeaking and clicking sounds. For optimal results, it is suggested that a disc be burnt at its rated speed.