What is the Difference Between CDs and DVDs?

(Digital Video Disc) Abbreviation, also known as high-density digital video disc. It is a newer generation product than VCD. DVD uses MPEG-2 technology and AC-3 standard to compress and encode video and audio signals. It can record images for 135 minutes. The difference with VCD is that its image resolution can reach 720 lines. ^[1]

The full name of DVD when it was born was "Digital Video Disc",

Lossless link technology

Encountered while burning

As an external data storage device, the hard disk is always exchanged with the host through the interface. Therefore, the quality of the interface technology plays a vital role in the speed of data transmission. ^[6]

Optical storage is external and built-in, built-in is installed inside the computer host, external-type

DVD burning speed

According to current standards, the DVD burning process is 1 (single-speed) or real-time (1.32MB / Sec transfer rate), which means that it takes up to 50 minutes to write a 3.95GB disc and 4.7GB. It takes even more than an hour for the CD-ROM. Let s compare it. It takes 72 minutes to fill a CD-R disc at the original rate of 0.15MB (IX) per second, using the fastest 8x speed device. (1.17MB / Sec) in just 9 minutes. For CD-R, 8x speed is usually considered as the practical limitation of single-head, single-speed recording.

Similarly, from a technical challenge point of view, 2x DVD-R recording technology is roughly equivalent to 8x CD-R. Inside the VDD Forum, there are different opinions that VDD-R will encounter a speed obstacle, making its future growth unable to extend to some discerning industries, such as the publishing and copying industries that are in high demand. This is mainly due to the fact that VDD-R depends on dye-based media, and dyes have limitations in light sensitivity. To overcome the problem of light sensitivity, it is necessary to use a complex recording strategy, and breaking the speed limitation of the recorder to modulate the recording pulse makes the recording strategy more complicated. Recognizing the limitations of this dye, some companies accepted a long-term perspective in their DVD-R media development projects and began to look for alternative dyes.

Disk At Once

Disk At Once method, generally abbreviated as DAO. Write-once

Disc diameter: 120 mm

Disc thickness: 0.6 mm / face

Laser wavelength: 635-650 nm

Numerical aperture: 0.6

Track pitch: 0.74 m

Minimum pit length: 0.4 m

Error correction code length: RS-PC

Modify the signal modulation mode: 8-16

Utilization rate of disc surface: 86.6 square centimeters

Bytes per sector: 2048-2060 bytes / sector

format

In order to protect intellectual property rights, the DVD Alliance divides the world into regions 1-6 by geographical area. Before loading the disc, please check the area code on the disc packaging. If it does not match the region code of the player, it may not be playable. Some discs and video discs have more than 1 district support (or all district support)

Surface layer capacity

Read Only Standard Definition

DVD-Video / DVD-ROM 1 1 4.7GB (DVD-5)

DVD-Video / DVD-ROM 1 2 8.5GB (

DVD-Video uses the Content Scrambling System method for data protection, but this solution

At the time when the DVD standard was formulated, copyright protection was placed in an important position, so only the area code restrictions and other anti-theft technologies designed by the first and second generation players in the early stage appeared, which undoubtedly hindered the DVD. With the further development of product technology, under the circumstance of increasing global copyright awareness, the copyright protection technology of DVD players and DVD-ROM drives, such as area code restrictions, has begun to be lifted. The copyright protection technologies often adopted on DVD include the following:

1. Copy-proof CSS encryption

CSS encryption (Content Scrambling System, content

There are two ways to achieve a doubled DVD, one is analog, and the other is digital.

Analog scale DVD, color component (component video) output signal, requires digital-to-analog converter

High-quality MPEG2 format DVD files are burned on 650MB CD-R discs with ordinary recorders and can be viewed on computer DVD drives and ordinary home DVD players. Files burned this way are called mini DVDs. ^[11]

The purpose of previous maintenance is to perform routine maintenance on the equipment, check the operating status of each channel, test indicators, and archive maintenance logs. With the application and development of various new technologies in the audio system, the meaning of maintenance has undergone a qualitative change. It is no longer the traditional concept of ensuring the normal operation of the system. The system's monitoring and adjustment, according to the system log and maintenance log, improve the system's operating status and provide a scientific basis for the improvement of the system. ^[12]

A faulty backgammon DVD player. The fault phenomenon is that the function keys on the panel are normal during playback. Sometimes it is normal and sometimes malfunctions when using the remote control.

First, check the remote control problem

The first thing we think about is whether the remote control battery has power. Take a new one. Assuming there is still a problem, then the battery problem that can be ruled out can be tested as follows.

2. Detection of transmitting and receiving circuits:

1. The purchase remote control uses a multimeter DC 50ma block connected in series in the battery circuit. The remote control is measured: the power consumption current during transmission is about 10ma, which is basically normal. It is suspected that the remote control caused the components of the printed circuit board to desolder or crystal due to the drop. The frequency offset makes the DVD player sometimes unable to receive the remote control signal and becomes ineffective. Turn on the remote control and check that there are no soldering or loosening of the solder joints of the circuit board components. After the crystal oscillator in the remote control is tested, the test machine is invalid. It is determined that the fault is not in the remote control transmitter but in the remote control receiving circuit.

2. Open the control panel of the DVD player. See that the camera uses a miniature integrated infrared receiver. Use a multimeter to measure that the + 5V power supply of the infrared receiver is normal. While pressing the remote control, measure the signal output pin of the infrared receiver and find that there is a jump voltage, but the CPU has not executed the remote control instruction. The reason for the failure of the remote control analysis may be that the output signal of the infrared receiver is abnormal, the CPU cannot identify it, or the CPU itself is faulty and cannot identify the signal output by the infrared receiver.

Third, replace the remote control with a new infrared receiver

The component infrared receiver's output signal is abnormal. Maintenance suggestions: Replace with a new infrared receiver.