Video tape recorder
A magnetic recording (short MAZ ) is an electronic analog or digital recording of content visual, aural or abstract nature on magnetic media, usually tapes ( tape recording ). In professional parlance MAZ stands for video tape formats and devices used in television stations. For home video formats and audio recording, the term is rarely used.
Similar to the "floppy" which was originally intended for the information carrier name in everyday language for the recording device has been misused. In television and television production companies decks are usually video player or VCR, which are used for cutting or playout.
Decks draw in colloquial usage is mainly characterized by the fact that they are timecode -capable, can be frame-accurately controlled by an interface control, frame-accurate cuts can run and professional standards for signal transmission use ( balanced audio cabling via XLR, transferring the image in composite (composite, color image blanking sync signal), component video (YPbPr ) or Serial Digital Interface (SDI ) via coaxial cable ). With SDI, the image and sound signals are transmitted digitally over a single video cable.
Typical decks of the early 21st century fit into 19 - inch cabinets, are one to two persons wearable and record the data on magnetic tape cartridges. Since 2004, MAZ devices are available which use hard drives. Also, optical media and hard memory cards are offered as an alternative storage media for tape.
Typical decks before the time of cassettes recorded on wound on large open reel magnetic tape and spent at least as much space as a 19 -inch cabinet. For ease of transportation they were rollable.
Today MAZ common formats are: Betacam SP, Digital Betacam, HDCAM, IMX, DVCAM, DV, D9, DVCPRO, DVCPRO HD.
Under television journalists, the term MAZ is used as a synonym for a film review ( classic manner with sound bites ). This film reports usually have a length of about two and a half to five minutes. In contrast, the NIF ( message in the film), a underlaid with moving images message that is not held for longer than 60 seconds.
Operating principle of magnetic recording
To store information on a magnetic tape, a recording head is needed. The write head is composed of a high-permeability core, and a coil having six or seven turns. By a recording current flowing through the coil, a magnetic field is generated, which must escape through a small air gap at one side of the magnet. The air has a much larger magnetic resistance, as has it the material of the write head. Now the magnetic field lines pass through the magnetic tape to be described. Due to the special band, the coating strip can be magnetized by the magnetic field. The information is stored in the form of small permanent magnets, small magnetic fields of the tape. The lower the frequency of the recording current, the greater the length of a permanent magnet. In its length so is the actual information that is later used when reading stored.
In the 1920s to the 1940s, tests began, pictures on shellac records ( Baird Phono Vision, 1928) to save and magnetic tapes. However, the results were unsatisfactory. It was not until 1956, with the Ampex VR 1000, the first machine before, the ( black and white video signal ) chronicled a composite video signal on 2-inch magnetic tape. It was the weight of the machine 400 kilograms and the tape reel weighed 15 kg. Another drawback was the construction on the basis of the electron tube, thus jitters were inevitable. The picture traces were cross- posted to the strip direction in the segmented Direct FM method, which 5 tracks at 60 Hz corresponds to NTSC transfer per field. This machine was nicknamed 2-inch quadruplex, which was usually abbreviated to 2-inch Quad. It was possible for the first time, sound (mono ), and record image on a tape, the section being initially carried out mechanically. Since video and audio head were not placed in the same place, you had to decide whether sound or image should run synchronously. Using the format found only in the studio to save footage and costly development and sampling times in the movie recording. As of 1958, the 2-inch quadruplex could also record in color in the NTSC system and in the same year the black and white recording was introduced to 2-inch Quad on German television .. As a further development from 1964 was the 2 " - high band ( hi- band ) available with stereo recording. During the same year Sony introduced the 1-inch EV format on the market, and the recorder was indeed heavy, but portable. the format was initially one hours wide in black and white on a customs record tape. later models EV -200 and 300 series could take color on the one inch wide tape using an external adapter., the system was only used for academic and industrial purposes.
The successor to Sony format CV format with 1/2-Zoll-Band already appeared in the same year and also served industrial purposes. The machine was a "skip -field " recorder, so it only every second image was always recorded, but this double sampled during playback. 1966 U.S. 2- inch black -and-white MAZ RCA " TR 22" for first PAL recordings has been modified in the WDR - color laboratory in Cologne and the lessons learned incorporated in 1967 in the color-enabled successor " TR 70 " one. A year later, Philips developed the first intended for use in the home video format using the LDL - video format. On the open reel 45 minutes the picture and sound could be recorded.
In 1969 a series of Akai 1/4-Zoll-Band whose recording time was 20 minutes per reel and was portable. The tape used the omega wrap the head drum.
In 1970, the Electronic Industries Association of Japan, a 1/2-Zoll-Videosystem, is involved in the Sony. It is the first time that several manufacturers, in this case mainly Sony and Panasonic join together and develop a format. There were disputes between individual members around the color specifications and to the Pilottonsystem. For the system existed reel and cassette devices and it found its way into the consumer segment, so that mainly find family videos and industrial films on the reels or cassettes. The original EIAJ specification was only black and white images and record only the development EIAJ -2 was able to record color images.
1971 Sony introduced U-matic on the market, a color -Under- system with 3/4-Zoll-Band and one hour playing time. The video bandwidth was max. 3.4 MHz, which is about half of the 2-inch systems. Recorded was the CVBS signal, two audio channels as well as a CTL track. Although not originally intended as professional video system, it has been used increasingly in the news by U.S. TV channels. The cassettes were smaller in portable devices.
Philips In 1972, the VCR format for home use one, in which the coils were in the compact cassette over each other. The maximum playing time is about 70 min. The format has two sound channels and works according to the Colour - under method. The format has been used by the WDR for the children's series Robbi, Tobbi and Fliewatüüt, which recorded directly on deck instead of the then customary footage and relied innovative techniques such as a blue screen.
The development of 2-inch quad went in 1974 in the final stage - the 2 " -inch super high - band could be in the Cut by timecode - controlled copy to another tape. A year later, Sony introduced in the U.S., the 1/2-Zoll-Heimsystem Betamax on the market, in which, after color- under method a composite signal and a sound track could be recorded. The game length is a maximum of 180 min., The bandwidth about 3.2 MHz, which corresponds to 250 lines of resolution. In the same year BTS / Bosch published the 1 -inch -B system on the market, which was for ARD and ZDF to the analog standard. Recorded was a composite signal by Direct FM method with the bandwidth of 5.5 MHz and segmented, with one field was spread over 6 tracks. The video tape is wrapped with this format to a small head drum in alpha - wrap. Due to the mechanical inaccuracies of the tape path is to play a Time Base Corrector required in the reproduction path and wherever Direct FM formats will play. For the use of slow and fast motion, a digital field memory was used. Three analog longitudinal audio tracks can be recorded, track 3 was used mostly for the Longitudinal Time Code, but a Vertical Interval Time Code was also recordable. The game lasted more than one hour. A portable device (BCN 20/21) was also developed in this are the two coils on each other and the playing time is 20 min.
In 1976, the Video Home System with 1/2 inch is presented by JVC. It captures a composite signal (chroma by Colour -Under- system) and a soundtrack with this. The playing time is up to 4 hours ( later up to 5 hours, which then were 10 hours long play). In the same year, the production of 2 -inch quad machines is set, recording media were then available for some time.
Sony brings 1977 U-matic high band (Hi -Band) in the European market, so that the existing U-matic format became the low band (Lo - band ), which represented the only U-matic system in the United States. Especially the ribbon width has been increased from 600 kHz (Lo ) bands at 1 MHz, allowing more colors were represented. The resolution increased from 250 to 260 lines. With the system the first ENG inserts were possible, such as the Rhine - high water from a rowboat in Cologne's Old Town.
Sony and Ampex lead a 1-inch C 1978, which established itself as an international standard. The specifications are similar to the one-inch B- format, but the signal recording was not segmented, so that a field of a track corresponds to longitudinal and four analog audio channels are available. One of them (Channel 4 ) was used per se of the MAZ as a sync, the 3rd as an LTC channel. The head drum slung in omega shape. A year later, Philips and Grundig make a video in 2000, a 1/2-Zoll-Band-System. However, it only uses 1 /4 inch because cartridges as MC's are reversible and offers eight hours of recording time in SP mode.
For the home user 1980 portable recorders and camcorders for the format VHS-C are presented. This reduced VHS tapes offer a maximum playing time of 30 minutes. A mechanical adapter VHS-C cassettes can also be used in conventional VHS devices.
In 1982, Sony Betacam before and JVC M ( also called Chromatrack -M ). Both systems draw on analog component YUV. The first 8 - mm Camcorder Video 8 appear in 1984 and work on the color- under method. Recorded were a composite signal of VHS- quality and two audio channels as AFM-Ton/HiFi-Ton.
1985 appear super-beta hi-fi equipment, the image resolution is 285 lines and record AFM tone. In the same year the equipment manufacturing for one-inch B and C formats is set. The belts are available up to the 1990s and until then as recording media in use. BTS attempted with a one-inch tape format the way to go for HDTV: The development has 1250 scan lines at 50 half-frames with analog component signals ( HD-MAC transmission format ), 4 tracks per segment, 8 segments per field and analog audio recording. The machine BCH 1000, however, was produced only in small numbers.
Sony unveils 1986 before the improved Betacam SP. There is now a large type of cartridge to 100 min, which nearly all transmissions can be received with a cassette. By default, the format of LTC and VITC timecode, two longitudinal tracks, two AFM audio tracks and a Luminanzspur with 5.5 MHz and a Chrominanzspur with 2 MHz bandwidth, so with a cassette format, the resolution of the one-inch systems is achieved for the first time because the video bandwidth mainly determines the sharpness or resolution. These were complex studio environments for this format required and any subsequent professional standards build on the experience and the specifications of Betacam SP on. The terms of the larger cartridges are 30, 60 or 90 minutes, for small 5, 10, 20 or 30 min. A recording device, the Sony BVW 85, is able to record two channels of audio as PCM, provided that the longitudinal audio track is used 1. Panasonic released as a competitor to Betacam MII up to 97 min. Runtime.
The U-matic SP standard is introduced as 1986. The resolution was enlarged at 330 lines / 4.2 MHz on. The timecode is now recordable as in Hi- band with an additional generator. New is also a Dolby C noise reduction for audio tracks, also port abele devices are available now for U-matic SP. With D1 the first digital cartridge format appears with 3/4-Zoll-Band, the sampling of the component signals in a 4:2:2 ratio was at 13.5 MHz ( luminance) and 6.75 MHz chrominance. The quantization was carried out with 8 bits. There are four mono or two stereo audio signals with max. 20 bit to 48 kHz can be recorded. An audio track can be recorded longitudinally for orientation in shuttle mode. There were 3 cartridge sizes with 12 min (S), 34 min ( M) and 94 min (L).
1987 S- VHS standard is introduced, with special bands can now theoretically up to 400 lines / 4 MHz resolution can be achieved. The tracks are, in contrast to U-matic written overlapping they are shorter, and the tape speed is very low. The format of the S -video connector feeder that keeps luminance and chrominance ( color and brightness ) transfers separately. It captures a composite signal, two longitudinal audio tracks, two AFM audio tracks and the VITC timecode. If the longitudinal audio track 2 is used, the LTC can be recorded. S -VHS position primarily by semi-professional use.
D2 ( D-2) is introduced in 1988 by Ampex / Sony and operates as D1 with a 3/4-Zoll-Band, but with composite instead Komponentenein or outputs. The image is quantized with 8 bits, the sound recording is identical to D1. The video bandwidth is 6.5 MHz. In the same year, Philips is a making of video 2000. Also, ED - Beta, which is not permeated appears. It had 520 lines with a much higher resolution than S -VHS is, however, not released in Europe. As required in super-beta Beta ED special recording media, otherwise only the normal beta mode is possible. 1988 Hi8 is introduced as the successor of the Video8 well. The resolution is higher than that of S- VHS and on the recording of longitudinal audio tracks will be completely waived. The audio track is recorded in the form of AFM sound and / or PCM audio with up to 15 kHz and an 8 mm timecode can be recorded.
1989, a year is introduced to D2 D3 already (D -3). The specifications correspond to the D-2 format, but the band is now only 1/2 inch wide, the match lengths amounts depending on strip thickness 50/64 min ( S), 95/125 min ( L) or 180/245 min ( XL). In the same year Sony HDVS brings to the market a one-inch - inductor-based system for digital recording of HDTV signals. Eight mono or four stereo audio signals can be recorded, two additional analog cue tracks and an analog LTC track. The system is only found in Japan use, it worked with YUV.
In 1993, Sony Digital Betacam ago. Recorded are YUV components that are 10 bit as opposed to 8 bit with other formats, digitized; in a 4:2:2 ratio, resulting in a data reduction to 1:2 results. The sound ( 4 audio channels) is digitized with 20 bits at 48 kHz. Digital Betacam is still the most widely valid broadcast standard. New was the SDI port. Component video, audio and time code are transmitted via self-clocking digital with 270 Mbit a BNC cable / s. The game length is similar to that of Beta SP. In the same year led Ampex DCT, a 3/4-Zoll-System a the United States. Component recording, 8 bit quantization, 4 audio channels quantized with 20 bits at 48 kHz. The operating mode is switchable between NTSC and PAL. The production of Betamax was adjusted.
In 1994, before the Panasonic D5 format ( D-5). It remained at 1/2-Zoll-Band, but was now working with digital component recording. It can be quantized bit with either 10 or 8. D-3- bands are given, otherwise the specifications as Digibeta or DCT. UNIHI appears from Sony on the Japanese and American markets. It is the first cassette system for HDTV and triggers HDVS from. The video bandwidth is 20 MHz, YUV recording and 4 audio channels.
A year later, BTS D6 ( D-6) presented an HDTV system with 30 MHz video bandwidth, component recording and 12 digital audio channels. W -VHS (Wide VHS) was introduced in Japan, with analog HDTV video bandwidth of 13 MHz, 4 MHz chrominance bandwidth. Recorded are YUV for video, AFM sound for audio and digital audio ( PCM audio ), each with 2 tracks. The production of U-matic system was adjusted.
The " Digital Video " format (DV format) was introduced on a broad scale at the beginning of 1996. It should be a low-cost consumer format. The data rate is 25 Mbit / s, which corresponds to a 5:1 compression ratio and a video bandwidth of about 5 MHz, 2 audio tracks recorded with 12 bit or 16 bit 44.1 or 48 kHz for some devices also PCM. Locked audio is optional. The Video Machine FAST was a pioneer in this field, it was more than one card (16-bit ISA) and three or four out of the computer to be placed boxes ( input and output, signal processing). The Media 100 system for the Mac at the time was also a leader, Windows 95 lacked as yet at important support. In the same year led a Sony DVCAM, which differs only by a 50 % higher tape speed (resulting from the higher track width) and locked audio from DV. Four audio channels are technically possible, but only 32 kHz and 12 bit. A 60 -minute DV tape is equivalent to 40 min DVCAM. Sony Betacam SX also released for use in the daily news / reporting. The system records in MPEG -2 standard on samples from 4:2:2 and compressed using DCT intraframe 10:1. The terms are similar to Digibeta. The counterpart of the competition camp was also 1996 D9 (D -9 ) or digital S system from JVC. There were no other devices except the decks, the compression by DCT is here 3.3:1 what s corresponds to 50 Mbit /. The development is based on the experiences of the S -VHS and W -VHS system. The cassettes correspond to the physical dimensions and VHS.
In 1997, the format was developed by Sony HDCAM and HD is the successor of Digital Betacam. HDCAM cameras record 1920 × 1080 pixels at 24, 25, 30 and 100 frames per second. The tape formats subsampeln 1920 × 1080 Picel for YCbCr 3:1:1 8- bit quantization. The format is used for the production of feature films, such as Star Wars or collateral. With over 30,000 systems sold to 2007 HDCAM is by far the leading professional format for digital cinema production and HDTV.
Panasonic 1999 led his DVCPro 50. A system that processes such as Sony's DVCAM, 50 Mbit / s. It scans 4:2:2 and compressed by DCT to 3.3:1. Most decks can edit DV, MiniDV, DVCAM, DVCPro (25) and DVCPro50 read, because the DV formats use identical cartridges. MPEG IMX was introduced by Sony in the same year. It is a format based on the MPEG technology. The video data can be directly accessed as files for editing, copying and so according to the calculator. The DCT compression 3.3:1 compression. It is for example used in the RBB news next BetaSX. Decks such as the MSW- A2000P Sony play Betacam, Betacam SP, Digital Betacam, Betacam SX and IMX from. They are in use in transmitters that turn on many formats, especially in the still frequently used 3-machine interface places as a player. The 1999 also come onto the market Digital8 records the same quality as MiniDV or DV standard, only on 8 mm tape. A 120 Hi8 cassette takes 60 min Digital8 video. Meanwhile, these devices have disappeared from the market due to price erosion in DV and the smaller cartridges and thus smaller camcorder. Most devices also give Hi8 and Video8 again.
2000 to today
JVC introduced the 2001 Digital Video Home System (D -VHS). It is characterized with double data rate uncompressed DVD to VHS tapes to, which is about 16-20 Mbit / s corresponds to and is the first consumer device for recording HDTV signals.
Sony unveils 2003, the development of HDCAM ago: HDCAM SR. It offers YCbCr and RGB 4:4:4 sampling with 10 bit quantization. A year later the production of the Betacam SP system is definitively discontinued; Recording media, however, were still available, but forced it to switch to Digibeta, BetaSX, IMX or equal to HD. Similarly, the format of high definition video is introduced in 2004, intended as semi-professional format. Is used, different from DV, MPEG2 GOP data reduction are used in the image group data reduction. The format works on the basis of the 1080i format, but a conversion to SD formats allow almost any device. Meanwhile HDV cameras are also used in the broadcast sector and the camera manufacturers distribute to professional users tailored cameras.
Other format extensions published in 2005 on the market: The formats of D5 (D -5) and DVCPro 50 from Panasonic has been further developed to D5 HD and DVCPro 100. As of 2006, manufacturers are offering more cameras and editing systems that are not requiring a magnetic recording and instead a tapeless recording at the derived from the Blu- ray Disc Professional Disc for Broadcast ( Sony XDCAM ) or Memory Card (Sony SxS, Panasonic P2, or Ikegami Editcam ) takes place.