Direct-to-disk recording (DDR) refers to methods by which analog signal

Analog signal

An analog or analogue signal is any continuous signal for which the time varying feature of the signal is a representation of some other time varying quantity, i.e., analogous to another time varying signal. It differs from a digital signal in terms of small fluctuations in the signal which are...

s and digital signal

Digital signal

A digital signal is a physical signal that is a representation of a sequence of discrete values , for example of an arbitrary bit stream, or of a digitized analog signal...

s such as digital audio

Digital audio

Digital audio is sound reproduction using pulse-code modulation and digital signals. Digital audio systems include analog-to-digital conversion , digital-to-analog conversion , digital storage, processing and transmission components...

 and digital video

Digital video

Digital video is a type of digital recording system that works by using a digital rather than an analog video signal.The terms camera, video camera, and camcorder are used interchangeably in this article.- History :...

 are digitally recorded

Digital recording

In digital recording, digital audio and digital video is directly recorded to a storage device as a stream of discrete numbers, representing the changes in air pressure for audio and chroma and luminance values for video through time, thus making an abstract template for the original sound or...

 to optical disc recording technologies

Optical disc recording technologies

Optical disc authoring requires a number of different optical disc recorder technologies working in tandem, from the optical disc media to the firmware to the control electronics of the optical disc drive...

 such as DVD

DVD

A DVD is an optical disc storage media format, invented and developed by Philips, Sony, Toshiba, and Panasonic in 1995. DVDs offer higher storage capacity than Compact Discs while having the same dimensions....

s, and CD optical disc

Optical disc

In computing and optical disc recording technologies, an optical disc is a flat, usually circular disc which encodes binary data in the form of pits and lands on a special material on one of its flat surfaces...

s . Magnetic storage

Magnetic storage

Magnetic storage and magnetic recording are terms from engineering referring to the storage of data on a magnetized medium. Magnetic storage uses different patterns of magnetization in a magnetizable material to store data and is a form of non-volatile memory. The information is accessed using...

 includes hard drives (HDD), magnetic tape

Magnetic tape

Magnetic tape is a medium for magnetic recording, made of a thin magnetizable coating on a long, narrow strip of plastic. It was developed in Germany, based on magnetic wire recording. Devices that record and play back audio and video using magnetic tape are tape recorders and video tape recorders...

 such as video tape and is different than flash memory

Flash memory

Flash memory is a non-volatile computer storage chip that can be electrically erased and reprogrammed. It was developed from EEPROM and must be erased in fairly large blocks before these can be rewritten with new data...

.

Generally these devices have the ability to convert analog signal

Analog signal

An analog or analogue signal is any continuous signal for which the time varying feature of the signal is a representation of some other time varying quantity, i.e., analogous to another time varying signal. It differs from a digital signal in terms of small fluctuations in the signal which are...

s into computer file

Computer file

A computer file is a block of arbitrary information, or resource for storing information, which is available to a computer program and is usually based on some kind of durable storage. A file is durable in the sense that it remains available for programs to use after the current program has finished...

s.

Direct to disk can involve permanent or semi-permanent non-volatile memory

Non-volatile memory

Non-volatile memory, nonvolatile memory, NVM or non-volatile storage, in the most basic sense, is computer memory that can retain the stored information even when not powered. Examples of non-volatile memory include read-only memory, flash memory, ferroelectric RAM, most types of magnetic computer...

 recording media. Computer hard disk drives are random access

Random access

In computer science, random access is the ability to access an element at an arbitrary position in a sequence in equal time, independent of sequence size. The position is arbitrary in the sense that it is unpredictable, thus the use of the term "random" in "random access"...

, erasable and rewritable non-volatile recording devices but have been referred to as "permanent" by some manufacturers of direct to disk systems.

Audio recording

In 1982, New England Digital

New England Digital

New England Digital Corp. , founded originally in Norwich, Vermont and eventually relocated to White River Junction, Vermont, was best known for its signature product, the Synclavier Synthesizer System, which evolved into the Synclavier Digital Audio System or "Tapeless Studio." The company sold...

 offered an optional hard disk recorder

Hard disk recorder

A hard disk recorder is a type of direct to disk recording system that uses a high-capacity hard disk to record digital audio or digital video. Hard disk recording systems represent an alternative to more traditional reel-to-reel tape or cassette multitrack systems, and provide editing...

 package for their Synclavier

Synclavier

The Synclavier System was an early digital synthesizer, polyphonic digital sampling system, and music workstation, manufactured by New England Digital Corporation, Norwich, VT. The original design and development of the Synclavier prototype occurred at Dartmouth College with the collaboration of...

 which allowed digital recording

Digital recording

In digital recording, digital audio and digital video is directly recorded to a storage device as a stream of discrete numbers, representing the changes in air pressure for audio and chroma and luminance values for video through time, thus making an abstract template for the original sound or...

 of monophonic 16-bit 50 kHz audio direct to a hard drive. This was the first digital direct to disk audio recorder available commercially. Stereo audio was not immediately available due to data input and output limitations on hard drives of that time.

Today, a majority of digital audio recording is preserved on hard disk drives.

Video recording

• Types:
  • Consumer: From camcorder
    Camcorder
    A camcorder is an electronic device that combines a video camera and a video recorder into one unit. Equipment manufacturers do not seem to have strict guidelines for the term usage...
    
    s to digital video recorder
    Digital video recorder
    A digital video recorder , sometimes referred to by the merchandising term personal video recorder , is a consumer electronics device or application software that records video in a digital format to a disk drive, USB flash drive, SD memory card or other local or networked mass storage device...
    
     (DVR) and set top box models like TiVo
    TiVo
    TiVo is a digital video recorder developed and marketed by TiVo, Inc. and introduced in 1999. TiVo provides an on-screen guide of scheduled broadcast programming television programs, whose features include "Season Pass" schedules which record every new episode of a series, and "WishList"...
    
     to personal computer
    Personal computer
    A personal computer is any general-purpose computer whose size, capabilities, and original sales price make it useful for individuals, and which is intended to be operated directly by an end-user with no intervening computer operator...
    
     based recorders.
  • High-end consumer – Pro: non-linear editing (NLE) systems like Avid Technology
    Avid Technology
    Avid Technology, Inc. is an American company specializing in video and audio production technology; specifically, digital non-linear editing systems, management and distribution services. It was created in 1987 and became a publicly traded company in 1993...
    
     video editing
    Video editing
    The term video editing can refer to:* Linear video editing, using video tape* Non-linear editing system , using computers with video editing software* Offline editing* Online editing...
    
     systems, to high-end tapeless camcorder
    Tapeless Camcorder
    A tapeless camcorder is a camcorder that does not use video tape for the digital recording of video productions as 20th century ones did. Tapeless camcorders record video as digital computer files onto random access data storage devices such as optical discs, hard disk drives and solid-state flash...
    
    s
  • Professional portable: For recording television productions/filmmaking
    Filmmaking
    Filmmaking is the process of making a film, from an initial story, idea, or commission, through scriptwriting, casting, shooting, directing, editing, and screening the finished product before an audience that may result in a theatrical release or television program...
    
     in the field with professional video camera
    Professional video camera
    A professional video camera is a high-end device for creating electronic moving images...
    
    s in digital cinematography
    Digital cinematography
    Digital cinematography is the process of capturing motion pictures as digital images, rather than on film. Digital capture may occur on video tape, hard disks, flash memory, or other media which can record digital data. As digital technology has improved, this practice has become increasingly common...
    
     for digital cinema
    Digital cinema
    Digital cinema refers to the use of digital technology to distribute and project motion pictures. A movie can be distributed via hard drives, optical disks or satellite and projected using a digital projector instead of a conventional film projector...
    
     productions.
  • Professional television studio
    Television studio
    A television studio is an installation in which a video productions take place, either for the recording of live television to video tape, or for the acquisition of raw footage for post-production. The design of a studio is similar to, and derived from, movie studios, with a few amendments for the...
    
    : From small systems able to record 2 hours to Large multi port playout
    Playout
    In broadcasting, playout is a term for the transmission of radio or TV channels from the broadcaster into broadcast networks that delivers the content to the audience...
    
     systems with a 100 hours of rec/play time

Consumer

• Miniaturization
  Miniaturization
  Miniaturization is the creation of ever-smaller scales for mechanical, optical, and electronic products and devices...
  
   of recording and storage technology for consumer video already allows the non-professional user to directly record home movies
  Home movies
  A home movie is part of the motion picture filmmaking process made by amateurs, often for viewing by family and friends. When the hobby began, home movies were produced on photographic film, but accessibility of video production with video cameras and low cost data storage devices has made the...
  
   to a permanent storage medium like DVD
  DVD
  A DVD is an optical disc storage media format, invented and developed by Philips, Sony, Toshiba, and Panasonic in 1995. DVDs offer higher storage capacity than Compact Discs while having the same dimensions....
  
  .
• DDRs are slowly replacing Consumer: Magnetic tape
  Magnetic tape
  Magnetic tape is a medium for magnetic recording, made of a thin magnetizable coating on a long, narrow strip of plastic. It was developed in Germany, based on magnetic wire recording. Devices that record and play back audio and video using magnetic tape are tape recorders and video tape recorders...
  
   based DV
  DV
  DV is a format for the digital recording and playing back of digital video. The DV codec was launched in 1995 with joint efforts of leading producers of video camcorders....
  
  , Digital8
  Digital8
  Digital8 is a consumer digital recording videocassette for camcorders based on the 8 mm video format developed by Sony, and introduced in 1999.The Digital8 format is a combination of the older Hi8 tape transport with the DV codec...
  
  , 8mm Video Format, VHS
  VHS
  The Video Home System is a consumer-level analog recording videocassette standard developed by Victor Company of Japan ....
  
   and MicroMV
  MicroMV
  MicroMV was a proprietary videotape format introduced in 2001 by Sony. This cassette is physically smaller than a Digital8 or DV cassette. In fact, MicroMV is the smallest videotape format — 70% smaller than MiniDV or about the size of two US quarter coins. Each cassette can hold up to 60 minutes...
  
   video tape recorders.

Professional portable

• Professional recording equipment using DtD transfers is beginning to appear. In April 2006, Seagate
  Seagate Technology
  Seagate Technology is one of the world's largest manufacturers of hard disk drives. Incorporated in 1978 as Shugart Technology, Seagate is currently incorporated in Dublin, Ireland and has its principal executive offices in Scotts Valley, California, United States.-1970s:On November 1, 1979...
  
   announced the first professional Direct-To-Disc cinematic camera aimed at the independent film-maker (using their disc drives).

• Infinity Series by Grass Valley
  Grass Valley (company)
  Grass Valley, previously known as Grass Valley Group, is a privately held company based in California, USA. Grass Valley produces technology for the video and broadcast industry. On January 29, 2009, Thomson announced its intention to sell the Grass Valley business unit...
  
  
  • Infinity Digital Media Camcorder – Infinity Digital Media Recorder
  • REV PRO Digital Media Drive-REV PRO Removable Media

Professional studio

• Professional television studio
  Television studio
  A television studio is an installation in which a video productions take place, either for the recording of live television to video tape, or for the acquisition of raw footage for post-production. The design of a studio is similar to, and derived from, movie studios, with a few amendments for the...
  
   DDRs video server
  Video server
  A video server is a computer based device dedicated to delivering video.Unlike personal computers, being multi-application devices, a video server is designed for one purpose; provisioning video, often for broadcasters. A professional grade video server records, stores, and playout of multiple...
  
  s are being used to replace video tape recorder
  Video tape recorder
  A video tape recorder is a tape recorder that can record video material, usually on a magnetic tape. VTRs originated as individual tape reels, serving as a replacement for motion picture film stock and making recording for television applications cheaper and quicker. An improved form included the...
  
  s (VTR)s and VTR Cart machines, that playout
  Playout
  In broadcasting, playout is a term for the transmission of radio or TV channels from the broadcaster into broadcast networks that delivers the content to the audience...
  
   television commercials and TV shows. Digital audio workstation
  Digital audio workstation
  A digital audio workstation is an electronic system designed solely or primarily for recording, editing and playing back digital audio. DAWs were originally tape-less, microprocessor-based systems such as the Synclavier and Fairlight CMI...
  
  s (DAW) are used in professional audio
  Professional audio
  Professional audio, also 'pro audio', refers to both an activity and a type of audio equipment. Typically it encompasses the production or reproduction of sound for an audience, by individuals who do such work as an occupation like live event support, using sound reinforcement systems designed for...
  
   recording studio
  Recording studio
  A recording studio is a facility for sound recording and mixing. Ideally both the recording and monitoring spaces are specially designed by an acoustician to achieve optimum acoustic properties...
  
  s

• The Media Pool (1994)- Disk Recorder by Broadcast Television Systems Inc.
  Broadcast Television Systems Inc.
  Broadcast Television Systems was a joint venture between Robert Bosch GmbH's Fernseh Division and Philips Broadcast in Breda, Netherlands formed in 1986.- History :...
  
   (BTS) was the first Professional Studio DDR. Received the Outstanding Achievement in Technical/Engineering Development Awards from National Academy Of Television Arts And Sciences in 2000–2001 for Pioneering developments in shared video-data storage systems for use in television video servers - Philips/Thomson
  Grass Valley (company)
  Grass Valley, previously known as Grass Valley Group, is a privately held company based in California, USA. Grass Valley produces technology for the video and broadcast industry. On January 29, 2009, Thomson announced its intention to sell the Grass Valley business unit...
  
  .

• Profile from Tektronix
  Tektronix
  Tektronix, Inc. is an American company best known for its test and measurement equipment such as oscilloscopes, logic analyzers, and video and mobile test protocol equipment. In November 2007, Tektronix became a subsidiary of Danaher Corporation....
  
   Models: PDR200-(1996), PDR300, PDR400

• Quantel
  Quantel
  Quantel is a company based in the United Kingdom and founded in 1973 that designs and manufactures digital production equipment for the broadcast television, video production and motion picture industries...
  
  :
  • sQ Class of Servers and sQ Clients

• Grande Vitesse Systems (GVS):
  • Profile GVS9000 2XU Pro, GVS9000 1XU Pro, GVS90000 7XU and other models of DDRs
  • Nomadic 1U 12xPro 24 hrs Uncompressed 10-bit 1080p Media Storage
  • Metropolis Media Servers
  • 9000CTR Dual Uncompressed HD Controller

• Grass Valley:
  • Profile PVS3000, PVS3500 and other models of DDRs
  • K2 Media Servers and Media Clients
  • Profile XP Video Servers
  • Profile XP Open SAN System
  • M-Series intelligent video digital recorder (iVDR)
  • Turbo intelligent digital disk recorders (iDDRs)

• Rave/SpectSoft
  • RaveHD
  • Rave2K

• Digitale Videosysteme
  Digitale Videosysteme
  Digital Video Systems AG is a German company specializing in digital cinema equipment.DVS is headquartered in Hannover, Germany, and is a leading manufacturer of high-performance digital video products for film, TV, post production and research and development...
  
   (DVS):
  • DVS Clipster DDR
  • DVS 2K Pronto DDR
• CarbonHD digital disk recorder

• The Digital video is stored on a storage area network
  Storage area network
  A storage area network is a dedicated network that provides access to consolidated, block level data storage. SANs are primarily used to make storage devices, such as disk arrays, tape libraries, and optical jukeboxes, accessible to servers so that the devices appear like locally attached devices...
  
   (SAN) hard disk
  Hard disk
  A hard disk drive is a non-volatile, random access digital magnetic data storage device. It features rotating rigid platters on a motor-driven spindle within a protective enclosure. Data is magnetically read from and written to the platter by read/write heads that float on a film of air above the...
  
   array.
  • Each year hard disk storage capacity gets larger and is able to hold hours of movies on Tera Byte systems.

Advantages of DDR over tape

• Quicker into the non-linear editing systems: no need to digitise
• The hard disks can store more than most video tapes
• Tapes and VTRs are expensive to maintain for the higher video data rates

Disadvantages of DDR over tape

• Hard disks are more expensive than video tapes
• Hard disks fail more frequently than video tapes
• Not practical to store a bank of hard drives for long term video storage.