Dvd overview
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Dvd overview



Pioneer began development of a new digital video disc format in 1991, with the goal of recording two or more hours of high-quality video on one disc, as a next-generation replacement for the LaserDisc.

In 1994, Pioneer introduced to the market an industrial model called the a Karaoke System, which could store and play back 2.1 GB of MPEG-1 data from a one-sided, 1.2 mm thick disc, using a 680 nm laser. In 1994, Pioneer also developed another digital video disc system which used an SHG blue laser. In response to Hollywood’s desire to have this kind of new system enter the market before multi-channel satellite broadcasting, Pioneer worked with Toshiba to propose a disc specification called SD, which used a red laser, at the end of 1994. Around the same time, Sony and Philips were promoting the MMCD specification. The major difference between the SD and MMCD specifications were whether the discs should use two 0.6 mm substrates bonded together, or a single 1.2 mm substrate, as an extension of the CD format. At the end of 1995, agreement was finally reached on a specification that combined the two-substrate approach of SD with the 8/16 modulation of the MMCD specification. At this point the DVD Consortium was formed, and DVD truly got started

In August 1996 the DVD Video Book was published, and the first DVD video players went on sale in November of the same year. The 3.95 GB Write-Once DVD-R Book, and the 2.6 GB rewritable DVD-RAM Book, were published in 1997. A DVD-RW Book and DVD-RAM Book, which define 4.7 GB rewritable formats, were published in 1999. A specification for 4.7 GB DVD-R was introduced in 2000. Two application specifications, the DVD Audio and the DVD Video Recording specification, were introduced in 1999. Following these specifications, DVD audio players, which provide high-quality multi-channel audio, and DVD video recorders, which allow recording to and playback of DVDs, were introduced to the market.

DVD Overview

.1 DVD History

Pioneer began development of a new digital video disc format in 1991, with the goal of recording two or more hours of high-quality video on one disc, as a next-generation replacement for the LaserDisc.

In 1994, Pioneer introduced to the market an industrial model called the Karaoke System, which could store and play back 2.1 GB of MPEG-1 data from a one-sided, 1.2 mm thick disc, using a 680 nm laser. In 1994, Pioneer also developed another digital video disc system which used an SHG blue laser. In response to Hollywood’s desire to have this kind of new system enter the market before multi-channel satellite broadcasting, Pioneer worked with Toshiba to propose a disc specification called SD, which used a red laser, at the end of 1994. Around the same time, Sony and Philips were promoting the MMCD specification. The major difference between the SD and MMCD specifications were whether the discs should use two 0.6 mm substrates bonded together, or a single 1.2 mm substrate, as an extension of the CD format. At the end of 1995, agreement was finally reached on a specification that combined the two-substrate approach of SD with the 8/16 modulation of the MMCD specification. At this point the DVD Consortium was formed, and DVD truly got started.

In August 1996 the DVD Video Book was published, and the first DVD video players went on sale in November of the same year. The 3.95 GB Write-Once DVD-R Book, and the 2.6 GB rewritable DVD-RAM Book, were published in 1997. A DVD-RW Book and DVD-RAM Book, which define 4.7 GB rewritable formats, were published in 1999. A specification for 4.7 GB DVD-R was introduced in 2000. Two application specifications, the DVD Audio and the DVD Video Recording specification, were introduced in 1999. Following these specifications, DVD audio players, which provide high-quality multi-channel audio, and DVD video recorders, which allow recording to and playback of DVDs, were introduced to the market.

1.2 Concepts and Structure of the DVD Format

A basic concept behind the DVD format is that, regardless of application, the physical format and file format should be common to all DVDs. (In the CD arena, formats differ between audio and data CDs.)

Structure of the DVD Format

The following table shows the relationship between the application format and the corresponding disc file format (as of 4/26/2001).* See Chapter 3 for more information on the UDF Bridge file format

* Video Recording is a real-time video recording format, which gives attention to editability

Read-only DVD discs have the same logical and file format, regardless of application. These formats are defined by the DVD-ROM Book. Read-only discs for computer use fall into this category.

The video format for read-only discs is defined by the DVD-Video Book. Similarly, the audio format is defined by the DVD-Audio Book; however, this specification also includes a subset of the video format.

The DVD-R format is a write-once format. Because one application of DVD-R is to test read-only disc software in the authoring process, DVD-R uses the same UDF Bridge format as read-only discs. A key feature of DVD-R is that after it has been recorded, it has essentially the same characteristics as a read-only disc. There are two specifications which define the 4.7 GB DVD-R format: the DVD-R for General, and the DVD-R for Authoring, specifications.

There are two formats for rewritable discs, DVD-RAM and DVD-RW. DVD-RAM uses a

physical format which is designed primarily for random access. For this reason, its format utilizes zone CAV with pre-addressing. DVD-RW, on the other hand, is an extension of DVD-R, and uses a physical format designed primarily for sequential recording. This format makes it easy to achieve physical compatibility between DVD-RW and read-only discs.

The Real-Time Video Format allows these rewritable discs to be used for real-time video recording without an authoring step, and allows editing after recording. This format is different than the video format for read-only discs, which assumes that the content will be edited before recording. All these rewritable disc formats incorporate copyright protection systems to prevent illegal copying.

The video specification was revised in December 2000, making it possible for the video format to be used with DVD-R for General and DVD-RW, as well as for ROM. This is an extension of the video format for use in consumer recording applications, and allows recording only of non-protected content. This application was specified for DVD-R for General and DVD-RW while preserving format compatibility with DVD-ROM, in both the file system and application levels. Further, a new recognition method was defined for distinguishing DVD-R or DVD-RW from DVD-ROM disc applications (DVD video discs). (Supporting playback of DVD-R / DVD-RW discs with this type of content is optional for manufacturers of DVD playback devices; there are DVD-Video players, DVD-ROM drive equipped PCs, and other DVD playback devices that do not play DVD-R or DVD-RW discs recorded in Video Mode.)

Application of this video specification to the DVD-RAM format is under consideration. (As of July 2001)

1.3 The Future of DVD

Next-generation optical disc systems using blue lasers (with wavelengths around 405 nm) are under investigation. It is anticipated that such systems would be able to record two or more hours of high-definition video stream, as from digital satellite broadcast. This requires capacities of 20 GB or more. To achieve this high capacity, discs and pickups with different structures than those used in DVD are under investigation. For instance, lenses with NA of 0.85 (DVD uses NA of 0.6) and a transparent layer 0.1 mm thick (DVD uses 0.6 mm) may be required.

Some types of discs, such as dual-layer DVD discs, are just not compatible with the blue wavelengths. This will require optical systems with two wavelength light sources to maintain compatibility with current DVD discs (three wavelengths to maintain compatibility with CDs). How next-generation optical disc systems will maintain backward compatibility with the current DVD specification is still an open technical issue.

Pioneer is energetically pursuing the development of a blue laser system. Below is a list of documents which publish the successes achieved at Pioneer in the development of a blue laser system.

Pioneer presentations regarding next-generation DVD development:

1. High Density Optical Mastering Using Photobleachable Dye (JSAP, Fall 1996)

2. High Density Optical Mastering Using Photobleachable Dye, Part 2 (JSAP, Spring 1997)

3. High Density Optical Disk Mastering Using Photobleachable Dye (ISOM, 1996)

4. Process Margin of 15 GB Disk Mastering Using Photobleachable Dye (ISOM, 1998)

5. Investigation of High Density Mastering Using Electron Beam (JSAP, Fall 1996)

6. Investigation of High Density Mastering Using Electron Beam (II) (JSAP, Spring 1997)

7. Investigation of High Density Mastering Using Electron Beam (III) (JSAP, Fall 1998)

8. High Density Mastering Using Electron Beam (MORIS/ISOM’97)

9. Investigation of High Density Mastering Using Electron Beam (IV) (JSAP, Spring 2000)

10. High Density Recording Using Electron Beam Recorder (ODS, 2000)

11. High Density Recording Using Electron Beam Recorder (ISOM, 2000)

12. 25 GByte Read-Only Memory Disk Fabrication Process (ODS, 2001)

13. 27.4 GByte Read-Only Dual Layer Disk for Blue Laser (ISOM/ODS, 1999)

14. Super High Density Optical Disk by Using Multi-Layer Structure (ODS, 2000)

15. 50 GByte Read-Only Dual-Layer Disk for the High-NA Objective Lens and Blue-Violet Lasers (ODS, 2001)

16. High Resolution NROO Detection in Ultra-High Density Mastering Equipment (JSPE, 2001)

17. Relationship Between Developing Time and Bit Form in an Electron Beam Mastering Process (JSAP, Spring 2001)

18. Investigation of Warping Reduction in Thin Substrates Using Quick-Cool Molds (JSAP, Spring 1997)

19. Investigation of Warping Reduction in Thin Substrates Using Quick-Cool Molds (II) (JSAP , Fall 1998)

20. Investigation of High-Density Signal Replication Using a UV Sheet (JSAP, Spring 2000)

21. Optical Disc Processing, One Step Ahead (JSPP, 2000)

22. Improved Characteristics of Optical Disc Substrate Forming Using Ultrasonic Injection Moulding (Part 2) (JSPP, 2000)

23. Analysis of Causes of Warp in Optical Discs (Plastic Forming and Processing Conference, 2000)

24. Investigation of Birefringence Control in Thin Substrates (II) (JSPP, 2000)

25. 25 GByte ROM Disk by Injection Moulding (ISOM, 2000)

26. Large Capacity ROM Disk by Conventional Injection Molding Process (ODS, 2001)

27. High Density Phase Change Optical Disk Using Limit Equalizer (PCOS, 2000)

28. First Trial of the Groove Recording Disk for High-NA Objective Lens Using Electron Beam (ODS, 2001)

29. Disk Tilt Compensation Using Liquid Crystal (JSAP, Spring 1996)

30. Disk Tilt Compensation
Using Liquid Crystal (II) (JSAP, Fall 1997)

31. Tilt Servo Using Liquid Crystal (JSAP, Fall 1997)

32. DVD/CD Compatible Pickup with Aberration Compensation (JSAP, Fall 1997)

33. Pickup Astigmatism Compensation Using Liquid Crystal (JSAP, Fall 1998)

34. Application of Liquid Crystal to Optical Discs (OSJ, 2000)

35. Tilt Servo Using a Liquid Crystal Device (ISOM/ODS, 1996)

36. 15 GByte DVD System Using a Liquid Crystal Panel (ISOM, 1998)

37. New Liquid Crystal Panel for Spherical Aberration Compensation (ODS, 1999)

38. Photo-Polymer Objective Lens for Blue Laser Disk System (ISOM, 2000)

39. Investigation of New Servo Error Detection Methods (Part 2) (JSAP, Fall 1999)

40. High North America Objective Lens for Blue Laser Disk System (ISOM, 2000)

41. Objective Lenses for Red and Blue Lasers (ODF, 2000)

42. Signal Simulation of 25 GB Read-Only Optical Disk System Using High-NA Objective Lens (ISOM, 2000)

43. Analysis of Jitter for Land/Groove Phase Change Disk (ISOM, 2000)

44. The Path from DVD (Red) to DVD (Blue) (MORIS/ISOM, 1997)

45. High-Density Reproduction System Using a Cross-Talk Canceler (MORIS/ISOM, 1997)

46. A New Equalizer to Improve a Signal-to-Noise Ratio (ISOM, 1998)

47. High-Density Optical Disc Playback Equipment Using a Cross-Talk Canceler (JSAP, 1998)

48. Signal Processing for 15 / 27 GB Read-Only Disk System (ISOM/ODS, 1999)

49. Tolerance of 3 Beam Cross-Talk Canceler (ODS, 2000)

50. 25 GB Read-Only Disk System Using the Two dimensional Equalizer (ISOM, 2000)

51. Next-Generation DVD System (LSJ, 2001)

Chapter 2 Physical Format of Read-Only Discs

2.1 Design Concept of the Physical Specification

2.1.1 DVD design target

The basic design of the DVD began with the goal of media for movies as content. Therefore, a basic goal was for a playback time of about 133 minutes, which is long enough to allow most movies to fit on a single disc.

However, since DVD was intended as a technology to replace LaserDisc (LD), DVD needed to provide at least equivalent video quality. As the result of many rounds of video quality evaluation, and with the assumption that DVD would use variable-rate video compression, it was determined that a data rate of 3.5 Mbps was the minimum requirement. Then, considering audio quality, flexibility for international use, and multimedia capability, it was decided to provide capacity for Dolby AC-3 audio in three languages (384 kbps x 3) and subtitles in four languages (10 kbps x 4), resulting in the design of a specification which required a disc capacity of 4.7 GB.

The difference between the DVD specification and the CD specification is not just the move from a near-infrared laser to a red laser; the difference is that the entire specification is designed to achieve a disc capacity of 4.7 GB, based on the evolution in technology in the ten-plus years since the CD was introduced in 1982. For instance, requirements for parameters such as disc eccentricity (radial run-out) and tilt have become considerably more strict than in the CD specification. This recognizes evolution in disc manufacturing technology, as well as the fact that the recording density has increase proportionally more than the laser wavelength decreased, reducing total system margin.

For example, the standard CD track pitch is 1.6 microns. Reducing this by the ratio of DVD to CD laser wavelength (650/780) would result in a 1.33 micron track pitch. However, DVD actually requires a track pitch of 0.74 microns, meaning that tracks are considerably more packed than one might expect. As the track pitch decreases, crosstalk increases, and the radial tilt margin is severely reduced. In order to achieve the required density the average track pitch variation was tightened to 0.01 microns. To reduce crosstalk the maximum allowed variation was also tightened to 0.03 microns.

To satisfy this specification, of course, it is necessary for the disc mastering equipment to be sufficiently precise, and the variability in playback device mechanisms and pickups must also be more tightly controlled than in CD players.

The specification known as DVD Book Part 1 describes the physical characteristics of a ROM disc needed to achieve such a system design. That is, the specification describes such things as the required disc mechanical properties, optical properties, and properties of the signal generated upon playback, as well as things like the modulation methods and error correction required to design DVD hardware. The DVD specification also allows dual layer discs and small ( 8 cm) discs; these definitions are also contained within this specification.

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