AET 2050 - DAW Production

1. Data Storage Media - Optical Storage

Objectives

• Compare and contrast optical and magnetic media
• Give important specs for the different CD "books"
• Contrast the different CD writing modes
• Give important specs for the various DVD types

Reading:

Chapter 5.1.7-5.1.14, Desktop Audio Technology - Rumsey

Compact Discs

• Most common optical storage device
• Not suitable for real-time editing and production, because of speed
• Excellent storage and transfer medium, especially with popularity of recordable CDs
• Most commonly used as format for audio delivery and storage (CD-DA) or data (CD-ROM)
• storage capacities of 650 - 700 MB

Specifications - "Books"

CD specifications are categorized defining physical dimensions, techniques for manufacture, how data is organized, etc.

There are many specifications, with many interactions - deistinguishing between them can be confusing!

Specifications were originally designed and released by Phillips and Sony.

Specs are organized into "books" described by colors. (The colors refer to binders in which these specs were gathered!)

Most common:

Red Book (CD-DA)

• standard audio format
• Data is limited to digital audio - 44.1K, 16-bit
• Up to 99 tracks per disc
• TOC placed at beginning of disc - all audio data after that
• data is etched into metal layer as "pits" and "lands"

Yellow Book (CD-ROM)

• modification of audio format to accommodate generic data
• data is stored in more conventional blocks, includes extra error protection
• no specific definition as to how data is defined - High Sierra/ISO 9660 are the most compatible (and best choice for cross-platform use)

Green Book (CD i)

• Special format for interactive processes
• Conains audio, video, data, programs
• requires a particular player, designed to connect to a TV set

Orange Book (CD-R)

• allows for recording of data by a user
• Wrtie-Once-Read-Many (WORM)
• constructed with a pre-formed "groove" containing a dye. The dye is heated during writes, changing refectivity
• TOC is written before the "standard" (Red Book) TOC area - unreadable by a Red Book player
• Audio CD can be "fixed" by creating a standard Red Book TOC - this is "finalizing"
• A recorded CD with a Redbook TOC looks like Redbook, but is not - Redbook defines manufactured CDs only!
• Part 2 describes the CD-R
• Part 3 describes the CD-RW

Multisession CDs

• Multisession CDs have multiple data volumes, or sessions on one disc.
• depending upon the method of recording, multisesion CDs can contain both audio and data.

Hybrid Audio/Data CDs

• Also referred to as CD Extra or CD Plus, Stamped Multisession or Mixed Mode
• Defines a gropu of formats that can contain several diefferent data types on the same disc.

  Mixed Mode

  • Contains ROM data on th efirst track, up to 98 audio tracks thereafter.
  • ROM drives can access the ROM data in the first track
  • CD players SHOULD skip the first track
  • Older players will not skip the first track - FULLSCALE STATIC WILL BE PRODUCED, DAMAGING SPEAKERS!

  CD Extra - Blue Book

  • A solution to the problems encountered with Mixed Mode by some players.
  • Two separate sessions are contained on the disc (multisession CD)
  • Audio in first session, data in second.
  • CD player only accesses the first session

Recording Modes for CD-R

Data need not be recorded all at once. Discs can be removed and data added at a later time if needed.

Orange Book defines an area (inside of the Red Book TOC area) for writing temporary TOC entries and for calibrating the laser power for recording.

"Disc-at-Once"

• All data is written at one time with a Red Book TOC. The data is prearranged and cannot be updated.
• The laser writes continuously. This is important for CD-A masters, as gaps are interpreted as errors!
• The writer MUST support DAO to get DAO.

"Track-at-Once"

• data tracks are written one at a time, with a gap between each.
• The TOC is updated as new tracks are added.
• Data can be read only if software supports it.
• The gap is interpreted as errors at a mastering plant - audio masters CANNOT be made as TAO.

"Multisession"

• An extension of TAO.
• With multisession, new TOC can be made, forming different volumes.
• CD-extra is made as multisession - audio first, then data after that.
• Reading drive must be multisession-capable

DVD

• Created to meet needs for video delivery.  Designers wanted a format that would:
  • have capacity and transfer rates for full-length movies
  • be backward-compatible with CD technology
  • single universal file structure
  • low cost and high quality replication
• DVDs meet all of these criteria:
  • smae physical characteristics as CD
  • seven times the data capacity per layer - up to 4 layers available
  • all DVDs muse the UDF (Universal Disc Format) Bridge for volume structure and file format
  • improvements in technology allow for cheap and dependable replication

Physical Characterictics

• DVD uses a different laser from CDs, using a different wavelength.
• A thinner substrate is used, providing for a higher density of data.
• DVDs can have two layers of data; the first beiung semi-transpaent, the second fully reflective.
• The laser must focus on two wavelengths in order to read the two layers.

• Result is a higher data density:
  • 4.7 GB   single side, single layer
  • 8.5 GB   single side, dual layer
  • 9.4 GB   double side, single layer
  • 17 GB   double side, dual layer

DVD Specifications - "Books"

• All DVDs use the same filing system.  The difference is what data is stored and whether or not it can be written.

DVD-ROM (book A)

• Basic format for all DVDs
• Used for data delivery

DVD-V (Book B)

• also known as DVD-Video
• First DVD format to be launched
• Format subset specific for video delivery
• Originally defined for convenient distribution of movies, including multichannel audio
• Can hold up to 133 minutes of video, and stereo or multichannel audio (compressed)

DVD-A (Book C)

• Also known as DVD-Audio
• Specification for storage of high-definition multichannel audio at higher sampling rates and bit depths
• Allows for multiple channels of uncompressed audio, and sampling rates of up to 192 kHz
• Video possible, but limited

DVD-R (Book D)

• Functionally equivalent to CD-R
• WORM
• two versions: one for professional use (A) one for consumer use (G).
• G contains 'content protection" features

DVD-RAM (Book E)

• sectored, similar to a hard drive (truly random-access)
• direct overwrite
• dual sided design requires a cartridge

DVD-RW (Book F)

• similar to CD-RW
• rewritable

DVD+RW

• non-compatible alternative to DVD-RAM
• useable as CLV (for video) or CAV (for random access storage)

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