·The main recording formats of CD-R and CD-RW
As we all know, the recording principle of CD-RW is roughly the same as that of CD-R. The difference lies in whether the disc can be recorded. Burn repeatedly, and the file format written to the disc is exactly the same. We can think of the recording format of a disc as the file system of the disc, which has basically the same function as the hard disk file system. The commonly used CD-R/CD-RW file burning formats currently include the following.
1. ISO-9660: ISO for short, was formulated by the International Organization for Standardization in 1985. It is currently the only universal optical disc file system. It is supported by any type of computer and all burning software. If you want all CD-ROM drives to read burned discs, you must use ISO-9660 or a compatible file system.
2. Rock Ridge: ISO-9660 file system for UNIX systems, supporting uppercase and lowercase file names, symbol characters and long file names. Since it is compatible with ISO-9660, even if the operating system does not support Rock Ridge, you can still view it through ISO-9660.
3. HFS: The full name is Hybrid File System (Hybrid File System). It is the optical disk file system used by Apple’s MAC machines. It does not support other operating systems such as DOS and Windows 9x/NT. .
4. Joliet: Microsoft’s customized optical disc file system, which is also an extension of ISO-9660. It supports Windows 9x/NT and DOS. Under Windows 9x/NT, the file name can display 64 characters. , and can use Chinese.
5. UDF: UDF is the English abbreviation of Universal Disc Format, a universal optical disc file system developed by the International Organization for Standardization in 1996. It uses standard packet writing technology (PW, Packet Writing) to simplify the use of the recorder. The UDF file system allows users to use the CD-RW recorder as if it were a hard disk.
6. Overburn: supports burning discs exceeding the standard 640MB, up to 1GB, but the burned discs have poor compatibility.
·Compatibility of CD-R and CD-RW recording formats
CD-R discs have the same size as ordinary CD discs, and the way they record data is the same as ordinary CD discs. Like CD-ROM discs, the laser reflection is also used to read data. Its laser reflectivity is 65, which is slightly lower than the 70 of CD-ROM discs, so it has strong compatibility.
Due to the use of phase change technology, CD-RW discs have a much lower laser reflectivity than ordinary CD discs. Therefore, when CD-RW was first launched, CD-RW discs could not be read in ordinary CD-ROM drives. However, with the emergence of MultiRead technology, this problem was quickly solved. Nowadays, using MultiRead technology has become a necessary means for CD-ROM optical drives. Any optical drive that uses MultiRead technology can read CD-RW discs. CD-ROM drives launched after the end of 1997 all use MultiRead technology. Due to the early development of technology, CD-R/CD-RW drives now have various mature and advanced functions of CD-ROM drives, and are well compatible with various CD-ROM discs and CD-R/CD- RW platter. These discs can be read in CD-R/CD-RW drives with no problem.
·Main DVD recording formats
Optical storage products are constantly developing in the direction of rewritable and large-capacity, and DVD discs have a large capacity, which is undoubtedly the next step after CD- Another ideal choice after R and CD-RW. Because of this, foreign manufacturers are currently vigorously developing rewritable DVD technology. At present, there are mainly four mainstream recording formats for DVD discs.
1. DVD-R (DVD Recordable) format
The data in the DVD-R format cannot be modified after being written, so it is also called write-once DVD burning. Format. The burning principle of DVD-R discs is similar to that of CD-R. It uses laser to write data on the dye layer, which can be read by DVD-ROM drive and can also be played in DVD-Video player. There are currently two DVD-R formats: DVD-R(G) and DVD-R(A). The difference lies in the wavelength of the laser during recording. DVD-R(G) uses a 650nm laser, while DVD-R(A) uses a 635nm wavelength laser. DVD-R(G) is mainly used for home and office users to record discontinuous archive files, and uses copy prevention technology. It is a unified standard established by the DVD Forum in 2000. DVD-R(A) was first proposed by Pioneer in 1998.
2. DVD-RAM (DVD Random Acess Meory) format
DVD-RAM is a rewritable DVD developed by a group headed by Japan's Hitachi, Panasonic, and Toshiba. It is supported by the DVD Forum (an industry group that defines and supports the DVD format) and is mainly divided into two types: computer-specific and home appliance-specific. Its recording principle is the same as that of CD-RW, and it also uses phase change technology. DVD-RAM recorders are somewhat similar to MO drives. DVD-RAM discs have a clip-on protective shell, so DVD-ROM drives and DVD players on the market cannot read them. The biggest advantage of DVD-RAM discs is that they can be rewritten more than 100,000 times, ranking first among all rewritable recording media. The standard DVD-RAM disk capacity established in early 1998 is only 2.6GB for a single layer and 5.2GB for a double layer. It was not until 1999 that the single-layer capacity was changed to 4.7GB, and in 2000 the double-layer capacity was also changed to 9.4GB. However, DVD-RAM has many shortcomings. DVD-RAM discs are fragile and difficult to maintain data integrity. They cannot be used on DVD players or DVD-ROM drives.
3. DVD-RW (DVD Rerecordable) format
The DVD-RW specification is led by Pioneer. The DVD Forum formulated version 1.0 of the specification in November 1999, and in 2000 Version 1.1 specifications will be completed in the middle of the year. DVD-RW products are positioned as consumer electronics products and mainly provide functions similar to the VHS video tapes of the past, allowing consumers to record high-definition audio-visual multimedia materials. However, the functionality of DVD-RW has also been applied to computers, with Apple and Compaq using DVD-RW drives as mass storage devices. The advantage of DVD-RW is its good compatibility. It is the earliest developed repetitive recording medium and can be used to store video, audio and other data, and most DVD-ROM drives can read DVD-RW discs well. . The original DVD-RW recorder cannot burn CD-R and CD-RW discs, but recently there are DVD-RW optical drives that support these recording formats. The disadvantage is that the burning speed is slower.
4. DVD RW (DVD ReWritable) format
DVD RW specifications are led by the DVD Alliance and are not official specifications of the DVD Forum. Microsoft has made it clear that in the next generation DVD RW is supported in the operating system. DVD RW products are also positioned in the fields of consumer electronics and computer storage products. DVD RW is an extension of the DVD standard. Compared with other DVD recording formats, its compatibility is the highest among several existing recording formats. DVD RW discs use phase change materials, and their reflectivity is the same as that of double-layer read-only DVD discs. Therefore, DVD RW eliminates the problem of DVD-ROM drives having difficulty reading data. The DVD RW drive has comprehensive functions and fast writing speed. It can read DVD-R/DVD-RW discs, but cannot burn DVD-RAM/DVD-RW discs. DVD RW provides about 1,000 copy times, which can help you complete video, audio and data storage. One disadvantage of DVD RW is that it cannot burn write-once DVD-R discs, but the DVD Alliance promises to release DVD R, a write-once disc dedicated to DVD RW recorders, this year.
·Compatibility of DVD recording format
Whether the DVD recording format is compatible with various DVD drives is the key to its survival. When a laser irradiates a disc of a certain burning format, the DVD-ROM drive reads the data through the reflected light from the disc. If the reflectivity is too low, the disc will be considered a "non-compliant" disc.
Among the above-mentioned DVD recording formats, the reflectivity of DVD-R/DVD-R discs that can only be written once is the same as that of ordinary DVD-ROM discs, so it is well compatible with all kinds of DVD discs. kind of DVD drive. The reflectivity of DVD-RW/DVD RW discs that can be written repeatedly is lower than the first layer of DVD-ROM discs. Some DVD-ROM discs have a double-layer recording surface. The so-called first layer refers to the layer on the surface. However, recent DVD-ROM drives can recognize even DVD-RW/DVD RW discs with low reflectivity. In addition, because the writing specifications of DVD-RAM discs are different from other optical discs, optical drives that do not support DVD-RAM discs cannot read them. By the way, DVD R/DVD RW discs sometimes cannot be recognized properly unless more than 1GB of data and images are burned on them.
Both DVD-RW and DVD-RAM recorders are backward compatible with DVD-R discs, that is, they can burn and read DVD-R discs, while DVD RW recorders can only use dedicated one-time DVD R and DVD RW discs cannot be burned or read, and special burning software is required when writing. DVD-RW and DVD RW drives cannot burn DVD-RAM format discs, and DVD-RAM cannot burn DVD-RW and DVD RW format discs.
In terms of formatting, the formatting time of a DVD-RAM disc is very short, less than 1 minute. Formatted DVD-RAM discs can be written and erased without special software, and are cheap, but are only available for computers with relevant drives. The formatting of DVD-RW discs is very long and takes up to an hour and a half. Although it takes about an hour to format a DVD RW disc, it can be used in 1 minute because it can be formatted in the background from the middle.
In terms of data writing time, a DVD-RAM drive takes 1 hour to store 4.7 GB of data on a DVD-RAM disc, a DVD-RW drive writes data about the same time as a DVD-RAM, and a DVD RW drive It only takes 25 minutes. Because DVD-RAM and DVD-RW drives only provide 1× burning speed, the speed is generally 2.77MB/s, while DVD RW can provide 2.4× burning speed, which can provide 11~26MB/s writing speed. .
Reference material: http://www.mydot.org/index.php?action=showamp;id=1640