Video Cassette Recorders

By Yuri Mikhaylovskiy

Review contents:

Professional video recording: Its perspectives in Russia Video Cassette Recorders New videocassette recorders ProfessionalDV of The JVC Company Videocassette recorders of D-9 format of The JVC Company Digital videocassette recorder from Panasonic Tape videocassette recorders of DVCAM format High Definition Videocassette Recorder of The Sony Company Sony Videocassette Recorders of D-10 Format (MPEG IMX)

In this article we are going to view videocassette recorders of different video recording formats that are today used for solution of tasks of television broadcasting of cinema-video production.

Equipment of analogous formats of video recording Betacam SP and S-VHS is widely spread in television centers of our country. However seems like manufacture plants of different professional video equipment had totally released the idea of analogous video recording. Equipment S-VHS is almost totally taken out of production. Betacam SP format also is going to be taken out. The Sony Company declared the stop in production of line of broadcasting group of Betacam SP video cassette recorders of BVW series, and also about significant decrease of volumes of production of Betacam 2000 Pro and 1000 series.

Absolutely different looks the situation with equipment that use digital recording on magnetic tape. The range of products is very wide and due to that the application field of facilities for recording/recalling of video materials enlarged significantly.

Videocassette recorders classify according to broadcasting standards and relation to application categories.

Broadcasting standards

HDTV — High Definition

This is the standard of high quality broadcasting, which is used in cinema and video production and soon possible HD signals will manage to get on the air. Characteristics of image in HD standard such as image pixels amount, amount of shots per second, scanning type can vary depending on required task. Of course, for viewing of HD video image special expensive monitors or projectors are required.

Formats of video recording of HDTV standard
HD-D5	Support of all HDTV resolutions, including 1080/60i, 1080/24p, 720/60p, 1080/50i, 1080/25p and standard SDTV. Digitalizing: 4:2:2 (Y: 74,176 MHz, PrPb: 37.088 MHz). Element in the line: Y: 1920, PrPb: 1080 (960); Y: 1280, PrPb: 720 (640). Shot frequencies: 24, 25, 30, 50, 60 Hz. Eight-channel sound for Surround 5.1. Accounted as standard for creation of cinema production.
HDCAM	HDTV formats: 1080/60i, 1080/24p, 720/60p, 1080/50i and standard SDTV. Digitalizing: 4:2:2 (Y: 74,25 MHz, PrPb: 37.125 MHz). Elements in the line: Y: 1920, PrPb: 1080. Shot frequencies: 24, 25, 30, 50, 60 Hz. Compression: 4.4:1. Digital bitrate: 185 Mbit/sec. Four-channel sound. Is used for filming and creation of cinema production.
DVCPRO-HD	HDTV formats: 1080/60i, 1080/24p, 720/60p, 1080/50i. Digitalizing: 4:2:2 (Y: 74,25 MHz, PrPb: 37.125 MHz). Elements in the line: Y: 1920, PrPb: 1080. Shot frequencies: 24, 25, 30, 50, 60 Hz. Compression: 6.7:1. Digital bitrate: 100 Mbit/sec. Eight-channeled sound for Surround 5.1. Is used for filming and creation of cinema production, wide range of cameras and videocassette recorders. Has HD-LP option.

SDTV — Standard Definition

In this broadcasting standard operate all air television of our country. In it image is represented by interlaced scanning with amount of lines in a shot of 625 and amount of shots per second 25.

SDTV formats of video recording divide into two classes: Professional and Broadcast.

To Professional class relay the equipment of digital formats, which has four times lowered color clearness in relation to brightness, and also analogous formats with horizontal resolution of not over 480 lines.

Professional formats
DVCAM	Digital component; intraframe compression: 5:1 DCT and VLC; bitrate: 25 Mbit/sec; representation: 4:2:0 (Y: 13.5 MHz, C: 6.75 MHz + 0 MHz); frequency range by brightness: 25 Hz…5.75 MHz, by color: 25 Hz…2.0 MHz; signal/noise: up to 55 dB; two channels of sound with 48 kHz sample rate or four channels of sound with 32 kHz sample rate; time sub-code.
DVCPRO (D7)	Digital component; intraframe compression: 5:1 DCT and VLC; bitrate: 25 Mbit/sec; representation: 4:1:1 (Y: 13.5 MHz, C: 3.375 MHz + 3.375 MHz); frequency range by brightness: 25 Hz…5.75 MHz, by color: 25 Hz…1.5 MHz; signal/noise: up to 60 dB; two channels of sound with quantization of 48 kHz + analogous audio track; time sub-code; CTL control track.
Betacam SP C 1000 series	Component; frequency range by brightness: 25 Hz…5.0 MHz, by color: 25 Hz…1.5 MHz; signal/noise: up to 48 dB; two linear channels of sound; time VITC code; LTC track; CTL control track.
S-VHS and Professional S	Separate recording of brightness and color components; horizontal resolution: 400 lines; signal/noise: up to 45 dB; two sound channels Hi-Fi + two linear; time VITC code (LTC instead of one audio channel); CTL control track.

Equipment of Professional class is recommended to use in sports and news programs. Today in our country Professional equipment is most popular due to low cost and is used almost in practical spheres of TV video production.

To broadcast class somehow relay all digital formats that use representation of 4:2:2 video signal in which color clearness is twice lower than brightness. That representation is considered as enough for digital transfer of video image with consideration of all Broadcast class requirements.

Digital S (D9)	Digital component; intraframe compression: 3:3:1 DCT; bitrate: 50 Mbit/sec; representation: 4:2:2 (Y: 13.5 MHz, C: 6.75 MHz + 6.75 MHz); frequency range by brightness: 25 Hz…5.75 MHz, by color: 25 Hz…2.75 MHz; signal/noise: up to 55 dB; two (four in some models) sound channels with sound quantization 48 kHz + two analogous audio track CUE; time sub-code; CTL control track.
DVCPRO50	Digital component; intraframe compression: 3:3:1 DCT and VLC; bitrate: 50 Mbit/sec; representation: 4:2:2 (Y: 13.5 MHz, C: 6.75 MHz + 6.75 MHz); frequency range by brightness: 25 Hz…5.75 MHz, by color: 25 Hz…2,75 MHz; signal/noise: up to 60 dB; support of 625 and 525 modes; four sound channels with sound quantization 48 kHz + analogous audio track; time sub-code; CTL control track.
Betacam SX	Digital; compression: MPEG-2 4:2:2P@ML; bitrate: 18 Mbit/sec; quantization frequencies: Y: 13.5 MHz, C: 6.75 MHz + 6.75 MHz; support of 625 and 525 mode; four sound channels with quantization of 48 kHz; track of time code; CTL control track; additional service track.
MPEG IMX	Digital; compression: MPEG-2 4:2:2 P@ML50 I-Frame; bitrate: 50 Mbit/sec; quantization frequencies: Y: 13.5 MHz, C: 6.75 MHz + 6.75 MHz; support of 625 and 525 modes; four sound channels with 24-unit digitalizing or eight sound channels with 16-unit digitalizing; track of time code; CTL control track; additional service track.
Digital Betacam	Digital; compression: Digital Betacam; representation: 4:2:2 (Y: 13.5 MHz, C: 6.75 MHz + 6.75 MHz); frequency range by brightness: 0 Hz…5.75 MHz, by color: 0 Hz…2.75 MHz; signal/noise: up to 62 dB; four sound channels with sound quantization of 48 kHz; track of time code; CTL control track; analogous CUE audio track.
Digital formats without compression
D5	Digital component; Sample rates: 10-bit digitization — Y: 13.5 MHz, C: 6.75 MHz; frequency range by brightness: 25 Hz…5.75 MHz; by color: 25 Hz…2.75 MHz; signal/noise: up to 60 dB; 8-bit digitization — Y: 18 MHz, C: 9 MHz; frequency range by brightness: 25 Hz…7.67 MHz; by color: 25 Hz…3.67 MHz; signal/noise: up to 56 dB; four 20-unit sound channels with sound quantization of 48 kHz, + analogous CUE audio track; track of time code; CTL control track; reproduction of D3 videocassettes.

Professional videocassette recorder has to meet numerous requirements to provide high level of functioning, reliability totally, and also, of course, to correspond to quality characteristics of video and sound signals usual for video recording format.

Videocassette recorders of any format of video recording classify by groups depending on operation tasks and relation to some requirements.

Classification of videocassette recorders categories

Studio

Videocassette recorders of this category are considered to be the most universal ones and most corresponding to requirements to quality and reliability. Exactly these videocassette recorders are the “face” of this or that video recording format. Studio videocassette recorders can be used almost in an television sphere: for reproduction/recording in air projection booth, use in linear and nonlinear projection booth of video editing, as a part of mobile television unit and for editor’s viewing. With their help can be done some works of video editing: form news collection to preparation of highly artistic programs.

Studio videocassette recorder has best characteristics in all series of produced equipment of this or that format. That is why for setting air projection booths, archives systems and other services with high responsibility always are set exactly these devices. Due to the same reason studio videocassette recorders are used for studying of quality parameters of video recording formats.

Let’s take a look at some peculiarities of videocassette recorders.

Build-in controller of video editing on front panel.

After combining videocassette recorder with others that have control interface RS-422, it is possible to produce assembly two-post video editing. For comfort of work the front panel of videocassette recorders of “studio” category can be brought out, set on video editing table and connected with videocassette recorder by cable. Studio videocassette recorder can be controlled remotely through the RS-422 interface due to what it ca be used for work with outside editing controller.

In this case by operation of preliminary recoil, regrowth and outlet operations in recording is controlled by editing controller. Different editing controllers can have different algorithms of producing of editing operations allow more flexible and deep use of videocassette recorder’s operations.

Regulated block of corrector of temporary distortion.

Studio videocassette recorder has the block of corrector of temporary distortion (fuel rod array). Beside operative regulations of this block are taken under the front panel and allow correcting by oscillograph/vector display standard deflections of video signal from the norm and exactly regulation of white level, taken out “zero” level of black, to change color saturation and color phase. All these regulations can be done specially from the console of remote control.

So, let’s sum up and name obligatory categories for videocassette recorders of “studio” category:

• obligatory coordination of all parameters to declared characteristics of video record format;
• opportunity of rack mount;
• presence of build-in editing controller operating through the RS-422 interface;
• opportunity of regulation of corrector’s parameters of temporary distortion (fuel rod array) directly from the videocassette recorder as well as from external control block;
• producing with by-shot exactness modes of video editing “pasting together”, “insert by video”, “insert by sound” on chosen channels, and building-in by temporary code;
• presence of composite entry/outlet of video (other entries/outlets can vary at different formats);
• presence of entry/outlet SDI (only at digital formats);
• presence of control interface RS-422 (other control interfaces can vary at different models);
• opportunities of reading/recording of temporary code (for analogous formats there are two types: LTC and VITC);
• presence of counter of CTL clock pulses;
• opportunity of synchronization against external source of carrying signal.

Well spread models of videocassette recorders of “studio” category:

AJ-D960 studio VTR

• Betacam SP: PVW-2800, BVW-75, players PVW-2600, PVW-2650, BVW-65;
• DVCAM: DSR-2000;
• DVCPRO (D7): AJ-D850B;
• Digital-S (D9): BR-D92;
• DVCPRO50: AJ-D970, AJ-D960, AJ-SD955, players AJ-SD930;
• Betacam SX: DNV-75, DNV-A75, players DNV-65, DNV-A65;
• MPEG IMX: MSW-M2000, MSW-A2000, players MSW-2100, disc BM MPEG IMX MAV-555;
• Digital Betacam: DVW-A500, DVW-500, players DVW-A510, DVW-510;
• D5: AJ-D580;
• format HDTV: HD-D5 — AJ-HD3700; HDCAM — HDW-F500, HDW-M2000; DVCPRO-HD — AJ-HD150, AJ-HD1600.

Editing

Actually these devices represent low priced and simplified variant of studio videocassette recorder. Decrease of a price happens due to refuse from some functional peculiarities as well as due to the simplifying of construction of video transport and worsening of technical characteristics. Usually, editing videocassette recorder is used in systems of linear or nonlinear video editing. As controller of editing comfortably and totally control all modes of videocassette recorders and control of temporary recorders in fact is not necessary as their function is done by video mixers, editing VM doesn’t have build-in editing controller and regulations of fuel rod array. When video-editing operator doesn’t have to do anything with videocassette recorder besides changing of videocassettes at all. That is why such device has on front panel the minimum of control organs however it produces the entire specter of operations of video editing.

The use of videocassette recorders of “Studio” category for these purposes usually finds itself to be irrational also from economic point of few.

The category of simplifies and low priced videocassette recorders that we call editing are very popular. It is specific that this category is present only at video recording formats of Professional class.

Peculiarities of videocassette recorders of “editing” category.

To them should be brought opportunities of remote control through RS-422 interface. In this case videocassette reorder uses the whole range of functions of control and synchronization under the control of external controller of video editing.

BR-D350 video player (top) and D-9 (Digital S) BR-D750 VTR

Editing videocassette recorder as well as studio has the block of corrector of temporary distortion (fuel rod array). As on the front panel there is no fuel rod array regulations, regulations can be only controlled from the special remote control panel.

In videocassette recorders of this group on the front panel there are only the organs of control of basic functions, exactly of modes of work (reproduction, rewind, recording). Almost on all of devices there is rotation wheel Jog/Shuttle and buttons of turning on of editing modes; amount of regulators is brought to minimum. Front panel is irremovable.

Digital Betacam DVW series VTR: general view (top) and view to tape transportation mechanism and video heads

Frequency characteristics, signal/noise ration and some other parameters are a bit worse comparing to the videocassette recorders of “studio” category, however they are in the limits of requirements to video recording format. Videocassette recorders of Betacam SP and Digital S formats have decreased amount of sound channels (two) comparing to videocassette recorders of “studio” category.

Field of application of editing videocassette recorders: systems of linear video editing, mobile television unit, air projection booths, but obligatory with external control facilities (editing controllers, remote blocks of video signal regulations and control). They also are used with nonlinear systems of video editing that have opportunities of control of videocassette recorder through RS-422 interface.

So, let’s sum up the obligatory criteria:

• opportunity of rack mount;
• opportunity of performing with by-shot accuracy of video editing modes like “pasting together”, “insert by video”, “insert by sound” on chosen channels, “insert by temporary code”;
• presence of composite video entry/outlet (other entries/outlets can vary at different formats);
• presence of control interface RS-422 with standard system of editing commands, compatible with editing controllers;
• opportunity of reading/recording of temporary code (for analogous formats there are two types: LTC and VITC);
• presence of counter of clock pulses CTL (not at DV and DVCAM);
• opportunity of synchronization from external source of carrying synchronization signal;
• presence of corrector of temporary distortions with remote regulation of levels of white/black, saturation and color phase.

Well spread models of digital videocassette recorders of “editing” category:

• DVCAM: DSR-1800, player DSR-1600;
• DVCPRO (D7): AJ-D455, player AJ-D440;
• Digital S (D9): BR-D750, BR-D80, BR-D85 and players BR-D350, BR-D50, BR-D51, BR-D52.

“Compact” category

This category of videocassette recorders appeared at the end of 1990th. Basically their task is to reproduce/record in mobile or on-table modes, viewing or control reproduction. Usually videocassette recorders work on recording in mobile television units together with nonlinear systems of video editing for editor’s viewing. It is very comfortable to use videocassette recorders of “compact” category for demonstration purposes for high quality reproduction through projection systems. Some videocassette recorders of this category have an opportunity of performing of editing operations when controlling through RS-422 interface. In spite of that compact videocassette recorders are used during producing of video editing very rarely as absence of enough amount of connecting cutoff points for integration in linear projection booth provides significant inconveniences. Besides many compact videocassette recorders have less “responsible” video transport, what reflects on editing speed as well as on comfort of work. That is why it is recommended to use compact videocassette recorders by their assignation and not to use them during editing attracted by their low cost.

Peculiarities of videocassette recorders of “compact” category.

Videocassette recorders have small weight and sizes, when rack mount take much less space what is highly necessary when setting on operator’s working table on nonlinear video editing in office of corresponded.

AJ-D250 compact VTR

Videocassette recorders of this category usually are powered from the mains of 220 V as well as from external low-voltage source.

Some compact videocassette recorders do not have editing modes. Other models however provide these or those editing opportunities and can be used for editing. However these opportunities are input for urgent cases, temporary schemes, but not for constant work.

Compact videocassette recorders have interfaces of control of external facilities, these can be RS-232, RS-422, Lanc, IEEE 1394, depending on the model. These interfaces are assigned for control of videocassette recorders from systems of nonlinear video editing or form systems of robotized reproduction or archiving.

DSR-1500 VTR

In tasks of videocassette recorders of “compact” group linear editing is not included. Video transports of these videocassette recorders are more inert and actually are not assigned for hard using in modes of editing search, during regrowth and repetitions or real editing. Some videocassette recorders however can operate as editing player, but exact regrowth with phasing for by-shot accuracy of editing is impossible in this case. This opportunity can be useful in cases when it is necessary to conduct editing in projection booth of another format: it is enough only to bring compact videocassette recorder in projection booth and connect it instead of one of existing players.

Obligatory criteria:

• compact and comfort during transportation;
• small weight;
• opportunity of power supply from mains of 220 v or from external accumulator or from other autonomous source;
• presence of modes of reproduction and recording;
• presence of interface of remote control.

Well spread models of videocassette recorders of “Compact” category:

• DVCAM: DSR-11, DSR-25, DSR-45, DSR-1500;
• DVCPRO (D7): AJ-D250;
• DVCPRO50: AJ-D94, AJ-D95DC;
• Betacam SX: DNW-A28;
• MPEG IMX: J-1, J-2, J-3;
• DVCPROHD: AJ-HD130DC.

“Portable” category

Facilities of this category are also called Backup-devices, i. e. facilities for reserving recording. The main task of this videocassette recorder is to conduct recording from video camera in field conditions. In this category are included videocassette recorders very much alike to previous “compact” category in functions and assignation. The main peculiarity of portable videocassette recorders is even smaller size, big mobility, opportunity of work from accumulator, and what is important, high integration with TV and video cameras.

Peculiarities of videocassette recorders of “portable” category.

Videocassette recorders of this category have small weight and sizes and are assigned for transportation in special bag.

The main application field of this group of videocassette recorders is main or backup recording from video camera of TV journalist’s set. The reason for creation of such devices was reliability of mechanisms of analogous video cameras and videocassettes. At the end of 1980th it was considered that standard TV journalist’s set of camera has to be accomplished with portable videocassette recorder to be secured from unpleasant situations. Connection to video camera usually happens through 26-vein cable, which provides power supply of videocassette recorder, transfer from the camera of video and audio signals, signals of temporary code, signals from videocassette recorder for viewing through viewfinder, signals of control “start/stop” from video camera. Portable videocassette recorder DVCAM can be also connected through IEEE 1394 interface, by which video and audio data, temporary code and control commands are transmitted.

At present portable VCR are almost not used for reserve recording. This is connected with that reliability of on-camera videocassette recorders is not high. Also economic aspect is very import: portable videocassette recorders are expensive.

DSR-40 VTR

But new portable digital VCR that use special hard disc as carrier provides high interest. Advantages of disc recording for nonlinear editing systems are obvious. Probably, in nearest future there will appear more disc portable VCR and this will be new direction of development of professional video equipment.

Videocassette recorders of “portable” class can be powered from external low voltage source or from power source of video camera.

These videocassette recorders have interfaces of control from external facilities. Some models are equipped with RS-422 interface of control from external facilities. Disc VCR can carry IEEE 1394.

Videocassette recorders of “portable” category analogous to named earlier compact ones are not assigned for use in editing purposes. If it is necessary some models can be used as editing player.

Obligatory criteria for videocassette recorders of “portable” category:

• opportunity of integration with TV or video camera for producing of reserve recording;
• compact and comfort while transportation, small weight;
• opportunity of power supply from external accumulator or other autonomous source;
• high small consumed power;
• presence of modes of reproduction and recording.

Well spread models of videocassette recorders of “portable” group:

• DVCAM: DSR-50, DSR-DU1 (disc);
• Digital Betacam: DVW-250.

“On-camera” category

This group of videocassette recorders analogous to previous “portable” one was developed for operating together with camera heads. However different from portable, which is separate facility, on-camera videocassette recorder has construction, which allows to attach it firmly to camera head. Such configuration is known in our country by video cameras of Betacam SP PVW-537, PVW-637, PVW-D35 formats, where to camera head are attached on-camera videocassette recorders of PVV or BVV series.

Peculiarities of videocassette recorders of “on-camera” category

Videocassette recorder is fixed on back pert of the camera, making one whole with it. Through multi-contact cutoff point between videocassette recorder and camera pass tens of informational and control signals: video and audio signal in both direction, synchronization signals, temporary code, control from “start/stop” button, power. Due to that the system is doesn’t differ from mono block functionally. Presence of such videocassette recorders allows choosing appropriate camera head for existing video recording format. For example, high quality and popular video cameras Ikegami, Thomson, Hitachi can be applied in TV journalist’s set due to applying of exactly on-camera videocassette recorders. For combination of cameras with videocassette recorders of different manufactures transmitting adapters are used.

Videocassette recorder has to provide own power supply and power of video camera. For this purpose on back panel of VCR is provided a square for connecting of accumulator. On all on-camera videocassette recorders, analogous to mono block video cameras it is possible to perform re settings of square for the necessary type of accumulators.

“On-camera” BR-D40 VTR with Iregami HL-45 camera

As videocassette recorder is the power part of video camera, it is equipped with outlet for local light source.

To videocassette recorder can be connected periphery sound sources: microphones or lines. Sound regulation can be hand, by indication levels or automatic, and schemes of automatic enrollments AGC are accounted for sharp overfall of sound level from microphone.

TV journalists’ set video camera has to have an opportunity of temporary code manipulation. On-camera videocassette recorder has switchers of modes of temporary code “Free Run/Rec Run”, and also an opportunity of setting of beginning temporary code.

Obligatory criteria of videocassette recorders of “on-camera” category:

• opportunity of firm fixing to on-camera head;
• providing of camera head with power supply;
• opportunity of accumulator setting;
• producing of recording and viewing reproduction operations;
• presence of sound entries;
• small size and simplicity of using.

Well spread mode4ls of digital videocassette recorders of “on-camera” category:

• DVCAM — DSR-1;
• DVCPRO (D7) — AJ-D90;
• DVCPRO50 — AJ-D90;
• Digital S (D9) — BR-D40;
• Betacam SX — DNV-5.

“Laptop” category

These videocassette recorders have facilities of local video and sound reflection and differ in full or part set of basic editing functions and also by presence of editing controller. Laptops can be single and doubled, which perform a portable editing couple. Single laptops can be integrated in two and three post systems of linear editing. Laptops are necessary for correspondent’s work in editor’s, office of correspondent, during reporting from the place of event or just in field conditions. As these facilities are assigned for using in extreme conditions requirements to reliability of laptop are higher than to any other category of videocassette recorders. Besides contemporary laptops are not worth than studio videocassette recorder in editing functions, but build-in into laptop controllers sometimes are better that controllers used in projection booths of linear editing.

Peculiarities of “laptop” videocassette recorders

Videocassette recorders have small weight and are assigned for mobile application. They distinguish in high reliability of mechanics and electronics.

Laptop has tip-up liquid crystal video monitor for reflection of video and build-in loudspeaker for sound control. Professional laptops are obligatory equipped with rotary control wheel Jog/Shuttle, buttons of control of videocassette recorders and video editing. The fact that professional laptops as well as studio videocassette recorders there is an opportunity of fuel rod array regulation is very important.

Videocassette recorder has fastenings for accumulators what increases facility’s mobility.

Sony miniDV laptop with camera connected to it

Videocassette recorders of “Laptop” category are editing. The majority of them perform the full set of editing functions, have build-in editing controller operating through RS-422 interface. At DVCAM and Betacam SX formats two laptops can be connected with each other in one all-in-one block. At DVCPRO and DVCPRO50 formats laptops are originally done as two videocassette recorders in one monolith body. Videocassette recorders of “laptop” category also can full work in the set of editing projection booths together with external video editing controller as videocassette recorders of “studio” and “editing” categories. The exception are highly miniature laptops DSR-V10 and GV-D900, which have limited set of editing functions and for editing require additional controller operating through Lanc interface.

Obligatory criteria:

• compact and comfort during transportation;
• opportunity of power from accumulator or other autonomous source;
• presence of modes of reproduction, recording and also opportunity of part or total performing of video editing operations;
• presence of build-in control video monitors of video and sound.

Well spread models of videocassette recorders of “laptop” group:

• DV — GV-D900;
• DVCAM — DSR-V10, DSR-70;
• DVCPRO (D7) — AJ-LT85;
• DVCPRO50 — AJ-LT95;
• Betacam SX — DNW-A25.

“On-table” category

This category of videocassette recorders came from the sphere of home techniques. Videocassette recorders of this group have a look and basic functions analogous to domestic devices.

In TV journalism very usually appear situations, when to the author of filmed plot it is enough to make editing of just few pasting together with putting of off-screen text. Such editing can be done at front of editor’s table, but not in projection booth, where work expensive and stuffed with other work videocassette recorders.

Panasonic AJ-DV2700 desktop VTR

Table videocassette recorders perform simple editing operations with accuracy of ±2…5 shots. They are used during preparing of news plots, in offices of correspondent, for drat editing and for editor’s viewing.

Obligatory criteria:

• small size and simplicity of using;
• presence of build-in or external editing controller for two-post editing;
• opportunity of editing in pasting together modes, inserts by video and by sound;
• presence of composite and Y/C video entries/outlets;
• presence of few control interfaces: 5-pin, Lanc, IEEE 1394;
• opportunity of reading/recording of temporary code (for analogous VITC videocassette recorders);
• presence of additional microphone sound entry.

Well spread models of videocassette recorders of “on-table compact” group:

• DV — AG-DV2700;
• DVCAM — DSR-30.

Other videocassette recorders

It is necessary to mention that videocassette recorders that have unique peculiarities or very different from other models.

New format of transfer of digital data SDTI is used in complicated server systems, such as Grass Valley Group, and also for speed transfer/ re-recording of video and audio materials in nonlinear editing systems. For today protocols SDTI and SDTI-CP are standardized.

Videocassette recorders, which support SDTI (SMPTE-305M):

• DVCPRO — four-speed BM AJ-D780;
• DVCPRO50 — two-speed BM AJ-D960.

Videocassette recorders, which support SDTI-CP (SMPTE-326):

• DVCAM — DSR-2000;
• Betacam SX — DNW-A75, DNW-A65;
• MPEG IMX — MSW-M2000, MSW-A2000, MSW-M2100.

Videocassette recorders, which support HD-SDTI:

• DVCPRO HD — AJ-HD150, AJ-HD1600;
• HDCAM — HDW-F500.

Videocassette recorders, which have mode of pre-read are already named in “studio” group however they should be distinguished separately by presence of function of pre-read. This mode is provided by:

• DVCAM — DSR-2000;
• DVCPRO50 — AJ-D970;
• Digitals (D9) — BR-D85E, BR-D92E;
• Betacam SX — DNW-A75;
• MPEG IMX — MSW-A2000, MSW-M2000;
• Digital Betacam — DVW-A500;
• D5 — AJ-D580.

Usage of pre-read function allows to economy one videocassette recorder in projection booth of video editing. With that it is not necessary to make interim raw material as in projection booth operate only one player; marking of editing mark simplifies.

Usage of function of pre-read significantly fastens some editing operations and besides lowers the general cost of equipment set. Usually, mode of pre-read is used during linear editing with the necessity of transfer of video effect from already recorded fragment to reproduce by the player.

Equipment of new format MPEG IMX allows connecting videocassette recorder to Ethernet. The special address is assigned to the facility and appears an opportunity of pumping of video stream via network in MPEG-2 format. When pumping of video material in computer systems data are stored as MXF file. Possibly, in the future connection between video facilities via Ethernet will become a usual mater by loading central matrix communicators of TV centers. This is the step to minimization of use of videocassette in video production. Support of MXF files at present is done by videocassette recorder MPEG IMX MSW-M2000, MSW-A2000, disc VCR MAV-555 and DSR-DR1000.

Disc VCR

Computer techniques came into television as video servers, station of nonlinear video editing, automation reproduction and archival system, facilities of storage of static images and stations of computer graphics. In spite of that tape videocassette recorders everywhere use in television production and computer technologies do not pretend to replace them.

Of course, for a very long time we want to have in the sphere of television production all comfortable opportunities of work with data, that are usual for disc mediums. And developers of equipment understand that. But to create new disc VCR that will actually replace videocassette recorder turned out to not so easy. The Sony Company produced a row of disc facilities of recording/reproduction that represent not just data server in computer understanding but exactly videocassette recorders that meet the requirements to studio device. To get wide distribution these facilities can’t due to their high cost.

First disc VCR MAV-555 actually substitute in functions and by control organs studio videocassette recorders of broadcasting class, for example, MPEG IMX MSW-M2000. This disc VCR combines advantages of powerful data server with fast Raid-array with advantages of studio tape videocassette recorder, which provide comfort in search of material by Jog/Shuttle wheel, linear editing, which perform any pasting together “nonlinear” instantly. But this facility has a price almost two higher than a price of studio videocassette recorders.

New disc recorders of Professional class: on-camera DSR-DU1 and stationary DSR-DR1000. They appeared in sale not so long ago, but already are very popular. Possibly Sony had felt the right direction and these models are the first ones in tape less era.

However these exact disc recorders, that can substitute videocassette recorders, more or less develop then with mobile disc carriers that substitute videocassette, is not clear. Everything is still developing.

Users look at DVD with hope. But the problem is that for today it is impossible to combine high quality and comfort, usual for DVD disc with low price, high reliability and volume usual for videocassettes. Exploitation DVD characteristics are far from perfection in out of doors conditions. These discs do not stand scratches or deformation. Broken disc with initial material is totally inappropriate when any left whole centimeter of initial videotape can be reproduced.

It is also unclear whether it is necessary to realize on mobile disc carriers such functions as imposition voice-over “on” the video directly in the camera, whether to realize on such disc a function of video insert by video or re-recording or temporary code? And if this will be realized how will the price increase? Or it is possible to deal without all that? It is impossible to answer these questions unambiguously. Manufactures of professional equipment don’t stand on the place and, we’ll hope, that in the nearest future disc formats will add to the tape ones.

Epilogue

Today, of course, linear video editing significantly gave up it positions to nonlinear, computer one. However not less than 30% of editing devices are linear as there is rather large number of works that require exactly linear editing due to some reasons. And as to video filming out doors formats of video recording on videocassettes are superior.

We’ll hope that due to new achievements in TV techniques our television will be qualities and interesting.