VCD: Movie and Television Primary Disc

DVD: High Definition Movie and Television Disc

EVD: High Definition Digital Movie and Television

MPEG4: Compressed High Density Movie and Television Disc

MP3: Compressed Pure Music

DVD has the characteristics of High Density, High Picture Quality, High Sound Quality, High Compatibility and high reliability and other characteristics.　High Density: DVD discs and CD discs are both 120mm in diameter, but CD discs have a capacity of 680MB and can only hold 74 minutes of VHS quality motion video images, while single-sided single-layer DVD recording layers have a capacity of 4.7GB, and are capable of holding an entire movie of 133 minutes and 20 seconds if played at an average data rate of 4.69Mbps, which is close to that needed for broadcast-quality television images. Double-sided dual-layer discs have a capacity of up to 17GB and can hold up to four movies on a single disc. This requires the use of more advanced technological means to increase the information recording density in DVDs, thus increasing the capacity of the disc. The following table lists several technical means used to increase the recording density of optical disks. Technical means CD/VCD DVD Mirror numerical aperture NA 0.45 0.6 Error correction code redundancy 31% 15.4% Channel code modulation 8/17 modulation 8/16 modulation Laser wavelength λ 780nm 650nm/635nm Spot diameter 1.74μm 1.08μm Channel spacing 1.6μm 0.74μm Minimum length of pit 0.83μm 0.4μm Pit width 0.6μm 0.4μm Capacity 650MB 4.7GB High picture quality: DVD adopts the internationally recognized moving image compression standard MPEG-2 (ISO/IEC13818), and its system stream transmission data rate is variable (1-10.7Mbps); at this stage, DVD-Video products use MPEG-2. Video products use MP@ML (i.e., NTSC TV 720 pixels/line x 576 lines/frame, 30 frames/sec; PAL TV 720 pixels/line x 488 lines/frame, 25 frames/sec, with a maximum data rate of 15 Mbps), which is one of the 11 MPEG-2 specifications, and achieves the broadcasting-level TV image quality (which has a horizontal resolution of 500 lines or more). To achieve higher definition picture quality, the corresponding advanced specification in MPEG-2 is also available.The system stream of a DVD consists of the main video stream (MPEG-2/MPEG-1 compressed stream), the sub-image streams (up to 32 streams can be recorded and played back for 32 types of textual movie dialog and (up to 32 streams for 32 kinds of text movie dialogues and karaoke subtitle display) and audio stream (up to 8 streams, supporting 8 kinds of language sound) and so on. The maximum data rate of the whole system stream is up to 10.08 Mbps. DVD also has new features such as multiple endings (to enjoy the development of different storylines), multiple angles (to view the image from 9 angles), Zoom, and parental control (to cut off the images that are not suitable for children to watch). There are 3 ways to choose the aspect ratio of the screen: Panorama Scan, 4:3 Normal Screen and 16:9 Wide Screen. PCM Dolby AC-3 Audio Sampling Frequency 48KHz/96KHz 48KHz 48KHz 48KHz Sampling Precision 16/20/24bit Compressed Data Compressed Data Data Rate 768Kbps ～ 32Kbps Minimum Main Stream: 64Kbps Minimum 2.304Mbps 48Kbps Max. 384Kbps One audio stream 1 5.1 Number of channels in 7.1 Maximum number of audio streams 2 to 8 Maximum 8 Maximum 8 High-quality: DVDs have 8 (7.1) independent audio streams, enough for digital surround 3D hi-fi sound. The DVD standard specifies that for NTSC television systems (e.g., in the United States and Japan), the use of Dolby AC-3 and/or linear PCM audio systems is mandatory; for PAL television systems (e.g., in Europe and China), the use of MPEG audio formats and/or linear PCM audio systems is mandatory. Table III gives the technical parameters of the three kinds of audio systems. 1992, the United States Dolby Laboratories released the AC-3 digital surround sound system to six completely independent channels (left, right, center, left surround, right surround and subwoofer, referred to as the 5.1 channel) and the full-band (～ 20KHz) high-precision lifelike soundstage, resulting in very good clinical digital surround High fidelity sound effect.　High compatibility: DVD player, DVD player and DVD-ROM/R/RAM can play CD discs; DVD player and DVD-ROM/R/RAM can play back VCD disks; DVD-ROM/R/RAM can also read CD DVD-ROM/R/RAM can also read CD-ROM disks.　High reliability: DVD adopts RS-PC (Reed Solomon Product Code) error correction coding and 8/16 signal modulation to ensure reliable data reading. Error Correction Code (ECC) block length of 16 record sector length (38688 bytes), corresponding to the length of 82.5344mm on the optical path; if the original BER is 10-3, after error correction, the BER can be less than 10-20, much lower than the BER required by the computer 10-12. In order to effectively prevent the software from being copied, in the United States, the Motion Picture Association of America (Motion Picture Association of America) actively participated in July 1996 with Toshiba, Sony and other 12 home appliances and computer companies on the copyright of the DVD software and anti-piracy to reach a unanimous agreement In October 1996, by the parties composed of the In October 1996, the DVD Technology Consortium announced that the DVD software and hardware used by the messy code technology and according to the six major regional codes of the regional distribution of software measures to realize the software copyright protection and reliable use.