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Frequently Asked Questions about CD, DVD and Storage
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- What is a CD-ROM?
- What is a CD-ROM drive?
- What is ATA/IDE?
- What is EIDE?
- What is ATAPI?
- Define data transfer rate
- Define access time
- What is digital servo?
- How do you measure CD-ROM drive performance?
- How does a drive's speed affect its performance?
- What is DVD?
- What are the advantages of DVD-ROM over CD-ROM?
- What is a CD-R/RW drive?
- What are CLV and CAV?
- What is AGC?
- How can I record RealAudio, MIDI, and MP3 on CD?
- What's Video CD and how can I make my own Video CD?
- What is the difference between the procedures of playing VCD and DVD?
- How to play a DVD-Video disc?
- What are the Phase-1 and Phase-2 of RPC (Regional Playback Control)?
- How can I set the DVD Region Code?
- What is the software decoder (PowerDVD) which related to some certain VGA cards and minimum system requirement?
- Is DVD-RAM a standard specification?
- What is UDF specification? Does DVD-RAM adopt UDF?
- What are DVD-RAM Type 1 & Type 2 Cartridges?
- What is the Sustained Data Transfer Rate of DVD-ROM and DVD-RAM?
- What is a CD-ROM?
CD-ROM is short for Compact Disc-Read Only Memory, which is a type of optical disk capable of storing large amounts of data - up to 680MB per disc. A single CD-ROM has the storage capacity of 470 floppy disks, enough memory to store about 340,000 pages of text.
CD-ROMs require a special machine to record the data, and once recorded, they cannot be erased and filled with new data. To read a CD, you need a CD-ROM drive. Almost all CD-ROMs conform to a standard size and format, so it is usually possible to load any type of CD into any ROM drive. In addition, most CD-ROM drives are capable of playing audio CDs, which share the same technology.
CD-ROMs are particularly well-suited to information that requires large storage capacity. This includes color graphics, sound, and especially video. In recent years, as the prices of CD-ROM drives have decreased, the tools for creating new CD-ROM titles have improved, and the CD-ROM industry has been expanding rapidly. To date, the most popular CD-ROM titles have been computer games and multimedia reference works.
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- What is a CD-ROM drive?
A CD-ROM drive is a device that can read information from a Compact disc. CD-ROM drives can be either internal, in which case they fit in a drive bay, or external, in which case they are usually connect to the computer ? parallel port or SCSI port. Parallel CD-ROM drives are easier to install, but they have several disadvantages. They are somewhat more expensive than internal drives; they use up the parallel port, which means that you can? use that port for another device such as a printer; and the parallel port itself may not be fast enough to handle all the data pouring through it. SCSI CD-ROM needs an extra SCSI controller board to have it connected. Typically, SCSI controller boards are more expensive than IDE ports.
There are a number of features by which CD-ROM drives are classified, the most important of which is the speed. CD-ROM drives are generally classified as single-speed, double-speed (2X), triple-speed (3X), quadruple-speed (4X), hex-speed (6X) or odo-speed (8X), deca-speed (10x), or triple quad-speed (12x). Within these groups, however, there is some variation. Two more precise measurements are the drive? access time and data transfer rate. The seek time, also called the access time, measures how long, on average, it takes the drive to access a particular piece of information on a disc. The data transfer rate measures how much data can be read and sent to the computer in a second.
Aside from speed, another feature by which CD-ROM drives are classified is compatibility with existing standards. If you plan to run CD-ROMs in a Windows environment, you need a drive that conforms to MPC II standard. If you want to view photographs stored on CD-ROM, make sure your drive conforms to the format of a Kodak PhotoCD.
Finally, you should consider how the drive connects to your computer. Most CD-ROMs connect via a SCSI bus. If your computer does not already contain such an interface, you will need to install one. Other CD-ROMs connect to an IDE or Enhanced IDE interface, which is usually the interface used by the hard disk drive.
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- What is ATA/IDE?
ATA (Advanced Technology Attachment) and IDE (Integrated Drive Electronics) both refer to disk drive designs that integrate the controller into the drive to reduce the interface cost and to ease firmware implementation.
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- What is EIDE?
EIDE, short for Enhanced IDE, is a new version of the IDE mass storage device interface standard developed by Western Digital Corporation*. It supports transfer rates of between 11.1 and 13.3 megabytes per second, about three to four times faster than the old IDE standard. In addition, it can support mass storage devices of up to 8.4 gigabytes per device, whereas the old standard was limited to 528MB. Because of its lower cost, enhanced IDE is expected to replace SCSI in many areas.
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- What is ATAPI?
AT Attachment Packet Interface (ATAPI) is a standard for devices such as CD-ROM drives and tape drives, which specifies an interface that is compatible with ordinary ATA (IDE) port. The advantages of using ATAPI hardware are low cost and compatibility with an installed IDE adapter.
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- Define data transfer rate
Data transfer rate is the speed with which data can be transmitted from one device to another. Data rates are often measured in megabits (million bits) or megabytes (million bytes) per second.
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- Define access time
Access time is the time a program or device takes to locate a single piece of information and make it available to the computer for processing. The access time for disk drives refers to the time it actually takes for the read/write head to locate a sector on the disk. This is an average time since it depends on how far away the head is from the desired data. Disk access times are measured in milliseconds (thousandths of a second), often abbreviated as ms. A drive with lower access time indicates a that it is a higher performance model.
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- What is digital servo?
This function automatically adjusts the gain/offset to ensure data reading accuracy and reliability. In contrast to the analog servo, which needs manual adjustment in the factory prior to its shipment, the digital servo requires no adjustment during manufacturing, guaranteeing high quality (complies with ISO 9001) and lower costs.
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- How do you measure CD-ROM drive performance?
The performance of a CD-ROM drive is dependent on two factors: data transfer rate and access time. Data transfer rate refers to the amount of data that a CD-ROM drive can send to a PC in a certain period of time. For example, a CD-ROM with 900 KB/sec transfer rate can read 900K (921,600) bytes of data and transmit it to a PC in one second. (Note that the transfer rate might alter depending on the power of the PC system.) Access time is the time required for a CD-ROM drive to find the desired data on a disc. A shorter access time indicates better performance. When talking about access time, the term "one third stroke" is often used. Stroke refers to the distance from the innermost track to the outer most track of a CD-ROM disk. One third stroke access time is the time it takes for a laser pickup to read data by moving 1/3 stroke over the CD-ROM disk.
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- How does a drive's speed affect its performance?
A CD-ROM's speed is measured in terms of its data transfer rate. The data transfer rate for a CD-ROM drive is measured in terms of bytes per second and measures the speed at which the drive can transmit data to the system? memory and CPU for processing. The higher the data transfer rate and the shorter the access time, the better the performance of a drive.
Older single speed drives could transfer data at 150K bytes/second, the same speed as a standard audio drive; but at this speed, images were jumpy and sound output had pops and cracks in it when the drive was used to read a video file such as a Video-CD clip. New multi-speed drives (20X, 24X, 32X) significantly improve a system's performance when handling image files. Today's PCs can handle more in the way of live video clips and animation, and Windows 95 offers direct support for multimedia; however, to take advantage of these new developments you should use a high-performance multi-speed drive like AOpen 20X, 24x and 32x speed drive, model CD-920E/CD-924E/CD932E or higher.
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- What is DVD?
DVD, short for Digital Versatile Disk, is the newest standard for optical storage, which specifies a disk that is the same size as a standard CD but is able to hold much more information. DVD was developed by an industry consortium of electronics companies led by Toshiba and Philips and it is anticipated the new standard will usher in a new era of growth for multimedia, interactive applications on the PC.
For PC applications, DVD will be used the same way the CD-ROM is used today. The main attraction for PC users is the larger capacity of the DVD disk. The capacity will be 17 gig on a double sided dual layer disk, 8 gig on a single sided dual layer, and 8.4 gig on a CD-R which will only be single layer but could be double or single sided. The PC will also be able to play DVD-Audio and DVD-Video, two standards developed primarily for home electronics devices. New ROM drives, called DVD-ROM, will be arriving on the market to accommodate the new disk format.
Advances in digital video and audio standards are coinciding with the development of the DVD to create unprecedented multimedia storage capacities. For instance, MPEG-2 video and audio compression will be used to compress still images such as scanned or pictures as well as full motion video. This compression will allow much greater storage than you could attain using a hard drive; for instance, a single-layer, single-sided DVD has enough capacity to hold two hours and 13 minutes of video. Some DVD-ROM drives will have a built-in MPEG-2 chip, and some others will use an MPEG-2 chip installed in the PC.
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- What are the advantages of DVD-ROM over CD-ROM?
DVD-ROM drives offer several advantages over CD-ROM drives, especially in the area of storage capacity:
- Greater capacity: With 4.7 gigabytes of storage capacity on a single layer and 8.4 gigabytes on a dual-layer disc, DVD-ROM offers more than 12 times the capacity of CD-ROM. When information is stored on both sides of the disk a single disk can hold up to 17 gigabytes, which is equal to 26 CD-ROM or 12,000 floppies.
- Faster data transfer: A basic DVD-ROM drive offers variable data transfer rate at an average rate of 1, 108 kilobytes per second.
- Flexibility: DVD will allow greater use and flexibility of Data Warehousing than ever before possible. One manufacturer has already developed a 100 disk juke box for DVD that can store 800 gig of data in a box only 2x 2
- Better Video: Because DVD-ROM has greater storage capacity and a faster data transfer rate than CD-ROM, it is possible to deliver up to full length movies on a one-sided disk using compression/decompression that yields broadcast quality video and stereo sound tracks for use in MS-DOS?/Windows?3.x. Other operating systems supply their own ATAPI CD-ROM device drivers. AOpen CD-ROM passed the Windows 95 specification and carries the "designed for Windows 95" logo.
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- What is a CD-R/RW drive?
CD-RW is a rewritable CD utilizing an innovative phase change recording material (Ag-In-Sb-Te). This breakthrough effectively increases data erasability and recording sensibility, which are two major drawbacks of conventional phase change recording material. During the write operation to a CD-RW, recording switches between the "amorphous" phase (recorded state) with lower reflectivity and the "crystal" phase (erased state) with higher reflectivity according to the temperature rising/falling through laser beam irradiation.
The CD-RW is ideal for personal uses, such as data back-up and making original CDs, because it allows a users to overwrite repeatedly. With CD-R, users can make discs for distribution, create electronic albums of digital camera images, store data that should not be revised or deleted.
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- What are CLV and CAV?
CLV stands for Constant Linear Velocity. To make the CD-ROM drive to achieve higher data transfer rate, the most common way is just simply increasing spindle motor speed. Almost all of CD-ROM makers adopt this way from their early 2X till now. For achieving constant data transfer rate, spindle motor need to run faster at inner track (500rpm for 1X) and slower at outer track (150rpm for 1X). However, when developing 12x or higher speed CD-ROM drives, the problems such as vibration, noise, disc data accessibility, reliability issue,etc. will have to be dealt with, so the way to solve this problem is to slow down the data transfer rate at inner track. CD-912E is the only drive in the market can provide actual 12X performance at both inner tracks and outer tracks.
CAV (Constant Angular Velocity), on the other hand, keeps the spindle motor running at the same speed while the CD-ROM is accessing data at inner and outer tracks. In this way, CD-ROM will have lower data transfer rate at inner track and higher transfer rate at outer track. As mentioned above on CLV design, it is getting more and more difficult to overcome those technical issues when CD-ROM's transfer rate is getting higher and higher. For example, spindle motor needs to running at 8000rpm (revolutions per minute) at inner tracks for 16X performance with CLV mode, and it's really too high for current technology as the maximum rpm of hard disk drive is only about 7200rpm. So we believe CAV is more suitable for higher speed CD-ROM design rather than CLV.
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- What is AGC?
Due to the physical nature of the CD-R disk, the electrical signal picked up from CD-R disk is weaker than normal CD-ROM disk. The "Automatic Gain Control" (AGC) feature allows the CD-ROM drive to automatically enlarge this weak signal to meet the electrical specification to dramatically improve the accessibility of CD-R disks. AOpen has implemented this AGC feature since CD-912E (12X) CD-ROM drive.
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- How can I record RealAudio, MIDI, and MP3 on CD?
The first step is to convert from whatever format the sound is in to WAV or AIFF. In some cases (e.g. MP3), many of the popular CD recording programs will do the conversion for you. If not, you will need to convert it to 44.1KHz 16-bit stereo PCM format. Once it's in WAV or (on the Mac) AIFF format, you can record it as you would audio taken from other CDs. Be sure to play it back once after you convert it to make sure that it came out okay. For more information about CD-R please refer to CD-R FAQ in the right side links.
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- What's Video CD and how can I make my own Video CD?
Video CD, or VCD, is a digital movie format. It's basically a
primitive version of DVD.
A Video CD is a kind of CD. It looks the same as a music CD or a CD-ROM, except that instead of music or software, it holds movies, using compressed MPEG-1 video. Its resolution is 352x240 (NTSC) or 352x288 (PAL), which is roughly comparable to VHS.
Compared to Video CD, DVD provides much higher resolution
(700x480), comparable to laserdisc or even better. DVD movies use MPEG-2 compression, rather than the MPEG-1 compression used by Video CDs.
A single VCD disc can only hold about 70 minutes of video, so for a typical movie, you need two discs. You can play VCDs back on a Video CD player connected to a TV, or on a fast PC with a CD-ROM drive. Some DVD players can also play VCDs.
Video CD was introduced by Philips and Sony in 1993. It never caught on in North America, but it became hugely popular in Asia, where most households didn't already have VCRs. In Asia, Video CD players are roughly as common as VCRs in North America: China alone manufactures
2 million VCD players a year.
Prior to the introduction of DVD in 1997, one reason to get VCDs was in order to watch Hong Kong movies. If you're a Hong Kong movie fan in North America (like me), and you don't live in a city with a large Chinese population, it's not so easy to find HK movies locally. But because
VCDs are so popular in Asia, almost all HK films released in the last few years are available on VCD: you can easily order them by mail for US $10-20.
The other big advantage of Video CD versus DVD is that it's
relatively easy to create your own Video CDs (e.g. from home
movies), using a CD-ROM burner. There's a lot of discussion
in the Video CD Q&A forum on this topic.
For more information about Video CD please refer to Video CD FAQ in the right side links. For more information about how to make your own Video CD, please refer to Video CD Q&A forum in the right side links.
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- What is the difference between the procedures of playing VCD and DVD?
DVD-Video features MPEG-2 video compression
technology; as to VCD, it's MPEG-1.In Windows 98/95-OSR2.0, you can play VCD with the
built-in Active Movie Control provided by Microsoft without installing any other software
or hardware. But this does not apply to playing DVD movies; you'll need some playback
applications (MPEG-2 decoder), either software or hardware.
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- How to play a DVD-Video disc?
First of all, you need an MPEG-2 decoder
specially designed for DVD-Video playback. Then some settings to configure the decoder
(either hardware or software) have to be decided, such as
1) Screen aspect ratio
2) Audio quality change
3) Language option
Secondly, the region code of your system
has to be set. You can find related information on the package of the DVD-Video disc you'd
like to play.
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- What are the Phase-1 and Phase-2 of RPC (Regional Playback Control)?
RPC (Regional Playback
Control) is required by Hollywood movie industry and defined by DVD Forum. The different
region code was recorded on DVD-Video disc for publishing in different area. Currently
there are Phase-1 and Phase-2 of RPC. And, DVD Forum requires all DVD products
should follow the RPC Phase-2 specification from year 2000. DVD-9632 drive includes both;
DVD-9624 is designed as Phase-1. When using DVD-9632 drive, you may select either Phase-1
or Phase-2 before configuring region code for your system.
For Phase-1, the region of your
system will be stored into the MPEG-2 decoder at last either hardware or software
solution. DVD-ROM drive has nothing to do. We recommend you to leave DVD-9632 drive on
Phase-1, then setup the region code by your MPEG-2 decoder.
For Phase-2, the region of your
system will be stored into the DVD-ROM drive itself at last, not MPEG-2 decoder. But this
process on Phase-2 region code setting will be irreversible, i.e., you won't be able to go
back to Phase-1 for re-setting the region code again.
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- How can I set the DVD Region Code?
To play DVD-Video titles, you have to set the region
for your system after installing MPEG-2 decoder. And the system will be fixed to one
specific region. The procedure is as follows:
1) Install your MPEG-2 decoder (either hardware or software) in your PC.
2) Insert DVD-Video disc, which has the specific region
code you want to set for your system, into DVD-ROM drive.
3) Start the application of MPEG-2 decoder. Normally, MPEG-2 decoder was fixed for specific region or requests user to setup the region for PC system.
4) Please follow up the setup procedure of MPEG-2 application. And set the correct region.
5) After all the settings above, your system will be configured for the specific region. You can start to play the DVD-Video of this region code.
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- What is the software decoder (PowerDVD) which related to some certain VGA cards and minimum system requirement?
Minimum system requirements for PowerDVD V1.5 (the latest versions are 2.0 and 2.5):
l) CPU: Intel Pentium II 266MHz or above
Intel Celeron 300A or above
AMD K6-2 300MHz or above
2) Memory: 16MB system RAM
3) Operation System: Windows 95 or Windows 98
4) Audio: ISA/PCI Audio card supporting 44.1KHz and 48KHz sampling rate
5) Video: PCI/AGP display card supporting DirectDraw 2.0 or above
6) DVD-ROM drive
The following VGA chipsets have been tested in PowerDVD V1.5 without any problem:
Nvidia Riva128,
Nvidia Riva128ZX,
Nvidia RivaTNT,
ATI 3D Rage Pro ,
ATI 3D Rage IIc ,
3DLabs PermediaII,
3DLabs PermediaIIv ,
3DLabs PermediaIIa,
3Dfx Banshee,
Intel740 ,
Matrox Millennium G200,
Matrox Mystique G200,
SiS6326 Rev. c3,
SiS6326 Rev. c5 ,
SiS6326AGP Rev. h0,
SiS6326DVD Rev.d1,
SiS6326DVD Rev.d2,
Trident 9850 ,
Trident 9750,
Trident 9880,
S3 Savage3D,
S3 Trio3D,
S3 VIRGE GX2,
S3 VIRGE DX/GX,
S3 VIRGE,
S3 Trio64V2,
Rendition V2200,
Silicon Motion Lynx3D,
Neomagic NMG4/5.
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- Is DVD-RAM a standard specification?
DVD-RAM is standardized by DVD Forum. Current DVD-RAM
drive and disc are Comfort to DVD-RAM Book (version 1.0). DVD-RAM drive is backward
compatible with CD family and forward compatible with DVD-ROM family.
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- What is UDF specification? Does DVD-RAM adopt UDF?
UDF(Universal Disk Format Specification) is standardized
by OSTA. UDF enable the file interchange among various platform and is optimized for large
contiguous files. Further more, since UDF uses the physical block size (2K for DVD-RAM
media) as its minimum storage block, it uses a media far more efficiently than FAT.
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- What are DVD-RAM Type 1 & Type 2 Cartridges?
DVD disc have 2 type cartridges. Type 1 cartridge disc
cannot be removed; Type 2 cartridge, the disc can be removed. The Type 1 cartridge is used
for double-sided DVD-RAM disc.
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- What is the Sustained Data Transfer Rate of DVD-ROM and DVD-RAM?
Pursuant to DVD-ROM Book, The Sustain Transfer Rate is
11.08 Mb/sec (1,385 KB/second).
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