Modern multiviewers

Author: Dennis Lennie

Published 1st September 2009


The monitoring of multiple video sources has been simplified and costs greatly reduced by the use of multiviewers. These make use of two principle technologies: large high-resolution video screens and the real-time resizing of video. The market is now well developed and provides a wide choice of specifications such as the number of inputs and their formats, and the number of images, or the ‘split’, image size and format of the output. Manufacturers also include other features designed to fit with a wide variety of applications – adding to the choice of products available on the market. Now the old monitor stacks that were common to video control rooms, MCRs, studio galleries and in OBs have been transformed to a very few multiview screens supported by a few high grade single-channel monitors for quality checking.
Multiviewers are also an established part of life outside the television industry and most people probably first see them used in the security business. But do not be confused! Not all multiviewers are the same. The fuzzy flickery video you see on the security monitors as you exit the supermarket bare no resemblance to the stunning image quality that can be produced with good broadcast quality systems!
Being a long-time supplier of video processing technology, FOR-A has been able to call its established advanced video processing technology for its multiviewer processors. These can then output to a wide choice of screens to suit customers’ requirements.
The applications for TV production can be divided into two areas: either to show that a signal is present, looks generally OK and to check roughly what’s happening, or to have a more detailed view of multiple inputs. An example of the ‘what’s happening’ scenario can occur in election results coverage. Typically there are many OBs spread out at various vote counts and the studio wants to see, at a glance, which one is about to declare its result. Here the requirement is to display a large number of inputs per screen. Other applications requiring a closer look at the video inputs mean that fewer sources be displayed at once. The former scenario could be covered using 16 inputs displayed on a 16-split screen, the latter is more likely may have a quad split. Often there it is possible to reconfigure the split to suit the current application or desired screen layout. Usually there are some front panel controls for basic set-ups with much more available via a PC application.
In all cases picture quality is an issue. By definition, each input picture is only able to occupy a relatively small area of the multiviewer’s screen. Many use 1920 x 1080 HD displays, so the area available to each of 16 16:9 video sources is theoretically only 480 x 270 pixels. In fact it is less as boards, tally and other information are usually added. Despite this limitation the quality of the video processing is still very noticeable. Good processing retains more detail and has less unwanted artefacts such as aliasing to produce a clearer view of each original source. Beyond broadcasting, this also has appeal in the security industry.
In essence a multiviewer processor could be considered akin to a video gallery in a box, requiring anything from input processing, standards conversion and frame synchronisation, re-sizing and positioning, text/ graphics (embedded audio-level bar charts, tally, clock, timecode, etc.), and vision mixing – the multi-split output. Now FOR-A has turned that analogy on its head by including a multiviewer processor within a vision mixer. First seen at NAB2007 as an option on the HVS-3800HS the inclusion of a 16-split multiviewer – supporting 4, 10 or 16-split view with tally and title display – within the HVS-300HS 1M/E HANABI SD/HD portable video mixer has proved to be a real boon – especially for those working on locations or at events. The whole HVS-300HS main unit is still just 1RU so transport and set-up are hugely simplified. Also, by using the ARCNET interface, the control panel as well as the multiviewer screen are each connected by a single BNC cable. Thus other possibilities arise such as moving monitoring and mixer control panel stage-side or onto the studio floor or for much more interactive set-ups; then moving them back to the gallery for the show.
Having a single screen that shows many video channels means that a lot of useful information can be send over one BNC (or DVI) cable, and that may well have uses away from the studio. Although a cable could be extended locally, FOR-A has gone the extra mile by offering an IP streaming interface as standard on its more recent models. This delivers a JPEG-2000 encoded version of the output, potentially making it available anywhere there’s an internet connection.
Multiviewer applications vary widely. FOR-A has concentrated on supplying high image quality and good value in a number of configurations based on compact 4-channel and 16-channel processors for SD, HD and analogue video. The combination of the range and the flexibility of each model is designed to fit with a broad range of broadcast as well as security requirements. Please see www.for-a.com for more details.

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