Convergence

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Bill S
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Joined: Aug 14 2000

Perhaps a smart move including Digital Stills on this forum, Bob.

How about some predictions on when the two technologies will converge into one?

We already have many DV cameras producing medium quality stills and the MVC-CD1000 “still” camera will record over 23 minutes of 320x240 mpeg “movie” onto its 8cm CD-R.

One just has to look at the rate of increase in IDE drive sizes (has been doubling every year but in the last year has quadrupled) to see that storage media is dramatically changing. How long can DV tape remain a limitation on camera performance?

If we can replace tape with solid media, for example, a mini DVD (or high density “son of DVD”) we could soon be looking at 1600 line HDTV which gives good quality 10”x8” stills from any frame.

When will it happen? My guess is about 4 to 5 years. About the realistic lifetime of some of the kit we are purchasing now!

Anyone else willing to stick their neck out and make a few predictions?

Alan Roberts at work
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Joined: May 6 1999

As far as I'm concerned, the convergence has already happened. My DX100 does stills at 720*576 (not very well) onto DV tape and my Olympus C3030 does 55 seconds of video (also not very well) onto flash cards. But each does it's own job spectacularly well for me.

But, when discs shrink, in the next generation, to below 2.5", we should be able to get 20G stores in cameras at least. Optical discs are here already in stills cameras (Sony), and we're being alerted to full oprfessional cameras with detachable disc-packs in the next 12 months.

So, watch this space....

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Alan Roberts at work
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Joined: May 6 1999

The demise of tape in cameras has been predicted for many years, as storage media get more dense. But the real event will only happen when we are prepared to accept MPEG in camcorders. And that's where the problems start.

DV and Digital8 (and all the other formats used in digital TV) are frame based. Each frame is compressed and stored as an entity, with no reference to other frames. MPEG, by contrast, is heavily dependant on the temporal properties of the image for it's efficiency. You can only get down from 25Mb/s (DV) to 4Mb/s or less (MPEG) by predicting images from previous or next. So, each MPEG frame is stored in a form that contains history and/or future links to other frames.

So what? I hear you all cry. Well, just try editing each. You'll find that you can make a cut on any frmae in a DV sequence without decompressing (cut the bitstream), but you can only cut on the (rare) fully indepoendant frames of MPEG (they happen only two or three times per second) without decompressing. So, with DV type compressing editing is a breeze and maintains original image quality, while MPEG compression requires decompression/edit/recompression, and thus suffers a quality loss each time.

There are ways around this, but the method is secret and I can't tell you any more, sorry.

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alan@mugswellvillage.freeserve.co.uk. Delete village for a spam-free diet.

Bill S
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Joined: Aug 14 2000

Alan,
The key event will be when we no longer have to carry around two cameras.

I also find the DX100 excellent for small stills but it can't compare with the larger prints from 1600x1200. It is not just the weight and size but also the expense of two systems. All that duplication of lenses and electronics.

Alan Roberts at work
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Joined: May 6 1999

Agreed, but the fundamental requirements are different for stills and video. So the sensor and lens system have to be different.

In a stills camera, you KNOW that the viewer will spend some time looking at one image, maybe even enlarge it or use a magnifying glass, that's how we view stills. So the detail has to be well preserved.

In a video camera, you KNOW that the viewer will be watching a moving image. And we also know that the eye is very adept at tracking moving objects, so it's best to move the camera with the forground object and throw the background further away using camera integration. So detail needs preserving only in those parts of the picture that the eye can be expected to track.

So what? It means that you can get away with far lower resolution in tv than in stills. Even HDTV, in the form now growing slowly in the US, is, as it's highest level, only 1920x1080, and that's interlaced. Also, bear in mind that the HDcam format is effectively only 1440x1080, and only produces resolvable detail up to about 1280 pixels. That, plus the usual interlace factor of about o.6, means the vertical pixel count reduces from 1080 (interlaced) to about 720. So the real resolution is around 1280x720, or about half what I can get with a small stills camera.

So, I'm going to be carrying 2 cameras around forever, or until video cameras have lenses and sensors that can do stills resolution of 2kx1.5k or better, and have switchable filters (electronic and optical) to do video.

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Bill S
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Joined: Aug 14 2000

quote:Originally posted by Alan Roberts at work:
So, I'm going to be carrying 2 cameras around forever, or until video cameras have lenses and sensors that can do stills resolution of 2kx1.5k or better, and have switchable filters (electronic and optical) to do video.

Exactly Alan - its that "until" or alternatively; until still cameras have media and processing that will allow storage of video."

Surely that is when we will have true convergence. The question is - Which direction will it come from? and when?

I certainly hope that we will not be carrying two cameras around forever.

[This message has been edited by Bill S (edited 19 October 2000).]