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HINTS & TIPS HE 111

 

Q
 I have an X-Box and wish to be able to play games and watch DVDs in 5.1 surround sound. What I will have to buy in-order to achieve this goal? I'm looking for a cheap/budget system that will give respectable sound for the money? I have around £250 to spend.
Christopher Woulds

A

It can be done of course but you must know that your budget is extremely tight moreover DVD playback on the X-Box is a secondary function and to make it useable you will have to spend some money on accessories. If you haven’t already done so you will need an X-Box ‘DVD Playback Kit’, which includes the remote control, and an ‘Advanced AV Lead’ with a optical bitstream connection --for the 5.1 sound output -- and S-Video and RGB video connections for the best possible picture quality. Together they should cost you less than £40, which leaves you a little over £200 for the rest of the system.  That is not a lot of money but you can certainly put together the core of a system and add to it as and when funds allow. Shop around, you can pick up a decent end of line AV amp/Dolby Digital decoder like the Technics SADX 750 for less than £120 and a pair of Mission M73s for another £100 or so at discounters such as Richer Sounds. Add a cheapie centre and some rears from your old system and you’re in business, and in a good position for an upgrade at a later date.

 

 

QUICK TIP

X-Box and the Sony Playstation 2 will play DVDs but they are first and foremost video games consoles so don’t expect too much. To be fair picture quality is not too bad – compared with a dedicated player – but you will have to pay extra for things like remote controls and proper AV outputs, moreover they have fewer convenience features and extra functions, like MP3 and CD-R replay. It’s also worth pointing out that neither console can replay Region 1 DVDs without modification or warranty infringing tweaks.

 

 

 

Q
I am on the verge of buying a Toshiba 42WP16, which I am told is a
re-badged version of the Panasonic TH-42PW4B. I assume that it suffers from the same lack of SCART sockets and so requires an extra tuner box, which adds another £500 to the cost. As this is my first go at home cinema, I am thinking of buying an all-in-one package, either the Sony DAV-S500 or DAV-S800. Would either of these provide the connections that I need, as I would prefer not to have to buy the AV tuner box? I have also seen adverts for various converter cables and boxes. Would S-Video to RGB be a viable option?
Alec Russell

A

Those two plasma panels are indeed very closely related and both of them lack SCART sockets but you don’t have to buy the AV tuner unit, provided you choose the rest of your AV components carefully, and there’s not too many of them… Both of those Sony DVD systems have S-Video outputs, which you can link directly to the Tosh screen, if you want to add a digital tuner and maybe a VCR they can be daisy-chained together and connected to the panel’s composite video input.

 

On your second question, the whole point about using an RGB signal connection between a DVD player and display device is that it is as close to unadulterated video as it is possible to get (on PAL equipment anyway). Further processing is necessary to turn RGB into S-Video and composite video and at each stage noise levels increase and the signal is degraded slightly. You can convert both composite and S-Video back to RGB format but since you are starting out with a reduced quality signal the extra processing will degrade it further so there’s no real benefit. 

 

 

QUICK TIP

The digital video information on a DVD is decoded by the main processing microchip and converted into analogue ‘components’, which emerge as a crisp clean RGB video signal. RGB is relatively easy to handle inside a microchip or on a circuit board however, because it requires three conductors it starts to get unwieldy when it comes to external connections to a display device moreover RGB signals are more readily degraded – compared with composite and S-Video signals -- by long cable runs and poor quality leads and connectors.

 

 

 

Q
I have an ageing LG 2280P DVD player, I was wondering if it is worth
chipping for multi-region or just getting the new player? I tried the hack published in HE108 but the player did not respond. Does this player play Video CD? In your opinion could you let me know which is the best combi DVD/VCR? I use my JVC S-VHS for editing/audio dubbing occasionally, but to save space I am thinking of getting a combi unit.
Sunil Shah

 

A

That hack should have worked, try it again but the truth is no hack can be guaranteed. They are for the most part unadvertised features that officially do not exist or require access to a hidden ‘service’ menu that end users are not supposed to fiddle with. Manufacturers also have a habit of updating player’s ‘firmware’ without necessarily telling anyone. This is the software program that controls how a player works, and on several occasions hacks for a particular model have suddenly stopped working.  As far as we’re aware only one LG player can play VCDs (LG 3350), which seems odd as there’s comparatively little difference between a VCD and an audio CD – see Quick Tip. We’re putting together a group tests on DVD/VCR combis right now so it might be a good idea to hang fire for a while.

 

 

QUICK TIP

The VCD format enjoyed a brief flurry of success in Europe and the US during mid-nineties. It remains popular in some Far Eastern markets but it quickly died off in Europe following the launch of DVD. The optical characteristics and the way data is organised on a VCD is very similar to an audio CD, some additional processing is needed for the MPEG1 video data but it is built into most DVD decoder chipsets and all that is required is for the facility to be enabled in the player’s firmware.

 

 

Q
I want to purchase a VHS video machine with RGB output, could you
tell me if such a machine is available since Thomson dropped the VTH
7090 model?
Bernard Hough

A

To date Thomson is the only manufacturer to have produced consumer VCRs with an RGB video output. It all started back in the early 1990s, following a collaboration with trendy French designer Philippe Starck. The reason for this oddball feature seems to have been to tie together Thomson’s very distinctively styled TVs and VCRs. Initially RGB was used to carry the on-screen displays, which made it difficult to use Thomson VCRs with any other brand of TV as back then comparatively few models had RGB inputs. Admittedly it made the fancy on-screen displays and graphics look unusually sharp but there was little or no benefit in terms of picture quality. That’s because VCRs do not use RGB video at any point in the recording or playback process; colour information and brightness signals are handled separately. In short it costs more to provide a VCR an RGB output, for no perceptible improvement in picture quality and these days it’s hard enough for VCR manufacturers to turn a profit on normally specified machines, let alone ones with apparently pointless features…

 

 

QUICK TIP

The colour information in a video signal contains a lot of very high frequencies that cannot be recorded directly onto VHS tape. The solution is to convert the signal to a much lower frequency, using an ingenious technique called ‘colour under’ (because the colour signal is recorded at a lower frequency than the brightness or luminance signal). This also overcomes problems due to minute fluctuations in tape speed, known as ‘jitter’ that would have a much greater effect on colour accuracy if the colour signal were recorded in its natural state.

 

 

Q
Living in South London my analogue TV reception is pretty poor (terrible
ghosting) so I still use my old ITV Digital box to watch digital terrestrial TV, although I intend getting a Nokia MediaMaster when the BBC's new digital schedule kicks off. My question is this, why is it that whenever I switch a light on or off or plug something in or out, there is a brief pause in my digital TV output? Picture and sound just freeze for about a second, then resume as normal, which is annoying if I am recording a programme, as all these 'freezes' are recorded as well.
Steven Hunter

A

This is an inherent problem with terrestrial digital TV and weak signal conditions. Picture freezing and other artefacts (see Getting Started) are caused by so-called ‘impulsive noise events’, which are ‘spikes’ that ride piggyback on the household mains. These are generated by inductive devices like motors and transformers or switches, thermostats and solenoids in central heating systems and appliances like washing machines, fridges and freezers. Normally it’s not a huge problem but if the spikes get through onto the digibox’s low voltage DC supply they upset the decoder chips, which are already struggling to make sense of a low grade signal. You might find that a main surge-suppressor/filter plug adaptor helps, they’re widely available from PC dealers and typically cost between £15 and £20. You should also check your aerial and if, as promised, the power output of the transmitters are increased the problem should go away.



Q
I have just purchased a Sony 32FQ75 TV and I'm amazed to find a fault
with it, a problem I've noticed with the same model at Comet and Curry
in-store sets. The problem is the left-hand side of the screen is slightly out of focus, something that's especially noticeable when the credits scroll up the screen. This is also visible when viewing Teletext and certain high-contrast images. I was disappointed to find this fault on a Sony product and a set costing me a whopping £1,400. What should I do about it?
Mohammed Ghaffar

A

None of the sets we’ve seen, based on this chassis and picture tube, showed any signs of mis-focus. That’s not to say it doesn’t occur – as your experience has proved -- and presumably the problem has now been fixed. It’s just possible the other sets you’ve seen are all from the same batch with the same fault but this seems unlikely as Sony’s quality control procedures are generally very good. There are several possibilities, TVs placed close to one another in a showroom can interfere with one another.

 

A you probably know TVs generate high intensity magnetic fields, not to mention a lot of RF (radio frequency) signals  – just hold a radio near a TV set and listen… 

 

One other possibility, and we’re close to scraping the bottom of the barrel now is that it might be that the other sets you’ve seen were not being properly displayed.

 

It could be that you have become acutely sensitive to picture defects such as a poor signal quality and mis-interpreted a focusing defect for the softened picture and muted colours that showroom TVs often exhibit under strong overhead lighting.

 

Have a close look at other makes of TV under the same conditions and see if they look the same.

 

 

QUICK TIP

Focus on a cathode ray tube (CRT) can be controlled in two ways: electronically and by physically moving the deflection coils mounted on the narrow neck of the tube. This may be adjusted automatically in the factory but it should always be checked visually before it is shipped. The coils in question generate a very precisely controlled magnetic field, which is responsible for sweeping a fine beam of electrons back and forth across the inside face of the tube. The visible picture lines we see on the other side of the screen are produced by a layer of coloured phosphor dots, which glow when struck by the zig-zagging electron beam.

 

 

 

Q
I've read about cutting squash balls as an alternative to isolation platforms. Would old mouse mats do the same job? In any event, I intend to put my gear on to a stone plinth. This consists of a 500mm high dwarf wall with 75mm stone slabs set on top. Will I still need to isolate my amp, etc? Also, do you think stand-mounters will sit on the plinth without the need for the stands?
Steve Sellars

A

Vibration can have a marked effect on the performance of audio and video components so any form of isolation, between an AV component and the surface it is sitting on is worthwhile. Squash and tennis balls are a popular low-cost alternative to the sometimes extraordinarily complicated and expensive contraptions that have appeared over the years but recycling old mouse mats is a new one. Depending on the type and thickness of the material they may well provide a useful degree of isolation but other inexpensive materials have proved to be even more effective. Apparently bubble wrap works really well, though the air in the cells can eventually leak out, particularly if the equipment is heavy, and it has to be periodically replaced.

 

It’s not a good idea to place speakers on the same surface and in close proximity to the rest of the system no matter how they are mounted. Low frequency travelling through the air will cause the casework and mechanical and electronic parts inside to resonate.

 

 

Q
I am planning to buy a camcorder and a home cinema system with a plasma screen (I understand all plasmas use progressive scan). Camcorders are available with either progressive scan or interlace scan. Would there be any problems viewing an interlaced camcorder output on a progressive scan screen and would there be any difference when the camcorder output is viewed direct, or (after editing and burning) via a Video CD?

Brian Sexton

A

You are right about plasma screens being progressive scan devices, and incidentally that holds true for most display devices that uses a fixed matrix of individually addressable pixels, including LCD and DLP screens and projectors. But we digress, the answer to your first question is no. Plasma screens are designed to operate with both interlaced and progressively scanned video inputs, so no problems there. Your second question is a little more complicated. Editing video footage shot on a DV camcorder on a PC will result in some small quality losses but they tend to go unnoticed when the recording is viewed on a PC screen or it is copied back to DV tape in its native digital format. However, when you make a Video CD of a DV recording the digital data is highly compressed, using the MPEG1 system, and there is a significant reduction in quality, down to the level of VHS in fact (and that’s on a good day), so yes, there will be a difference. 

 

 

GETTING STARTED 1

Camcorders with a progressive scan recording mode caused a minor stir amongst serious video moviemakers when they first appeared a couple of years ago. Progressive scan video has a much more film-like quality, compared with conventional interlaced video. That’s because each frame of the image is a separate entity – much like a frame of movie film – rather than being made up of meshed half-frames or ‘fields’, which is the case with interlaced video. Interlacing has two distinct drawbacks; when there’s rapid movement in the picture the slight displacement between the two separate fields shows up as jagged edges and wobbly still frames and it produces a noticeable flicker. It’s not too bad on a smaller screen – 28-inches or less, say – but as displays get bigger so the flicker becomes more pronounced. Various techniques have been devices to overcome flicker, the most successful one being 100Hz display, but even they can’t match the smoothness of progressively scanned image.  However, progressive scan on camcorders hasn’t had much impact in the wider world of home video movie making and it is mostly confined to top-end models; at least one manufacturer has abandoned the facility on consumer machines. 

 

As a matter of interest PAL camcorders with progressive scan are much sought after in the US by video professionals. That’s because the PAL system operates at a frame rate of 25 frames per second, which is very close to the 24fps of movie film and PAL recordings look a lot more like movie film than material shot on NTSC progressive scan camcorders, which have 30fps frame rate.

 

 

GETTING STARTED 2

Back in the old days of analogue video it was relatively easy to quantify picture quality in terms of definition, colour fidelity and noise but digital video, whether from DVDs, digital video recorders and camcorder or terrestrial or satellite transmitters, has spawned an entirely new generation of picture defects. They tend to be grouped together under the umbrella term ‘artefacts’ but there are several quite distinct types of artefact, which you may feel are worth getting to know, if only to sound more knowledgeable when you complain to your TV or DVD supplier. 

 

Block Noise – this is when the parts of the picture turn into large coloured squares, often just before it freezes. It’s caused by an interruption in the flow of data  – from the disc, tape or TV transmitter – the decoder tries to correct for the errors by filling in the bits of the picture with a ‘best-guess’ coloured block.

 

Macro Blocking – very similar to block noise but this is a more specific by-product of MPEG encoding. The picture turns blocky when the compression system discards too much information, which it deems unimportant. The result is fewer larger pixels and it shows up most clearly in backgrounds and darker areas of the picture, which appear more blocky and less detailed than the foreground. 

 

Mosquito Noise (aka Gibb Effect) – this is another MPEG encoding by-product and is caused by low data rates. It shows up as incorrectly coloured pixels around the edge of an object and is sometimes seen around fine details like writing and on end credits

 

Dot Crawl – common on analogue video systems it looks like a coloured fuzzy cloud along and around sharp edges and small objects. It shouldn’t happen on DVD but you may see it when the player is connected to the TV using a composite video lead, which is another good reason for using S-Video or RGB connections whenever possible.

 

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Ó R. Maybury 2002, 1110.

 

 

 

 

 

 

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