Systems of the slow motion on the basis of disk recorders by Doremi Labs

By Sergey Zudov

Review contents:

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Recording of digital video on computer hard disks gets the increasing popularity. Already all leading manufacturers of the professional video equipment in their arsenal have one or several such devices, either it be the disk tape recorder or on-camera hard disk unit. Undoubtedly, at approximately identical price with tape devices the disk units offer more opportunities to users. In particular, instant access to any frame from hundreds GBytes of material and an opportunity of reading of the information in any order allow without any difficulties to organize the cheap and reliable systems of the slow motion on the basis of these devices

Digital disk recorders with one or several channels work precisely the same as professional VTRs, but in this case the video is recorded on an internal hard disk, instead of on the cartridge. Today disk tape recorders allow to work with all standard video interfaces and video signals, including signals of high definition (HD). The opportunity of the control with RS-422 and use of a time-code does work with these units almost similar to work with general tape recorders.

Under the right one of pioneers and leaders of introduction of disk devices in professional video production American company Doremi Labs is considered.

Based in 1985, Doremi Labs originally specialized on development of multichannel workstations for audio studios of the TV program production. In 1996 Doremi Labs has presented on the market the first disk videorecorder V1. The device has turned out so successful, that has very quickly won popularity all over the world. And today already more than 5 thousand users use V1 for TV broadcasting, animation, video, audio editing etc. Russian users too have estimated the advantages of this equipment: in our country already some dozen broadcast studios work on equipment from Doremi Labs.

Today a modelling row of digital disk tape recorders is submitted by four various series, each of which consists of several modifications. The basic difference between these series is the data storage format:

• V1 M-JPEG series designed for work in Motion JPEG format and allows to work with compression 2:1…34:1;
• V1 MP2 series designed for work in format MPEG-2, 4:2:2@ML (up to 50 Mbit/sec;
• V1 U series designed for work with 10- or 8-bit non-compressed video;
• V1 UHD series designed for work with a high definition (HD) signal; supported formats are 720p, 1080i (50/60 Hz), 1080p (24, 25, 30 frame/sec).

Inside series the models differ on volume of disks, number of channels and sets of inputs/outputs. Generally the set of video inputs/outputs may contain the following interfaces: composite, S-Video, component, SDI, HD-SDI (V1 UHD) and Video Sync. Models also may have up to six channels of an analog audio and up to eight channels AES/EBU and SDI (each). Control may be carried out through Ethernet 100baseT or two RS-422 ports.

V1 recorder

Recording time can be in the range from several dozens of minutes to several hours or dozens of hours and depends on disk volume. V1 allows to connect from one up to three internal SCSI-disks (with an opportunity of hot replacement) and up to fifteen external disks on each SCSI-port.

The general features of their units are the following:

• Layout in the rack (3U or 5U);
• Convenient user interface;
• Instant access to video within the frame accuracy;
• Creation and assignment of an individual name to videoclip and playlist;
• Direct, cyclic and slow motion;
• Record on a remote hard disk, DVD-RAM, MOD;
• Conversion of formats QuickTime, TIFF, TGA etc.;
• Remote control through Ethernet or RS-422 with use of standard protocols.

Models of disk recorders of V1 series are provided by the forward panel on which the control buttons, the Jog/Shuttle handle, the controller of change of playback speed and optional LCD-display are located. Compatibility with protocols Louth (Harris), Odetics, SGT and Etere allows to use the V1 recorder in structure of the automated off-the-air equipment room.

Multichanneling of disk tape recorders and instant access to a material do this equipment as optimum devices for the slow motion realization. To the operator it is not required any time for tape rewind to the beginning of the necessary episode. For him it is necessary only to adjust the second channel on the slow motion from the necessary place and to switch on in required time. While this channel will reproduce the chosen part of record in a slowed-up way, the other channel will continue to record video in a general mode.

Other useful function following from the features of disk tape recorders, is a delay of broadcasting on time (Broadcast Time Delay). For this purpose the device may be simply transferred in the mode “repeating cycle” and adjusted on any duration of delay time. The maximal duration of delay time is limited only by used compression ratio and the size of the installed hard disk.

Material provided by Ovako Company