Slashdot Mirror

http://en.wikipedia.org/wiki/Integral_imaging: "Indeed, it has been demonstrated that an integral image can very accurately reproduce the wavefront that emanated from the original photographed or computer-generated subject, much like a hologram, but without the need for lasers to create the image; see Fig. 2. This allows the eyes to accommodate (focus) on foreground and background elements, something not possible with lenticular or barrier strip methods."

http://www.broadcastpapers.com/whitepapers/IBCDeMontfortCGContentfor3DTV.pdf: "The perceived advantages of integral imaging are that only a single aperture camera is needed to capture the 3D data. In addition the display is a full 3D optical model, the model is correctly scaled throughout the image space, and in viewing accommodation and convergence occur naturally thereby preventing possible eyestrain."

A prototype microlens array based flat panel video (as in, non-static) display was built by Hitachi in 2006, and they claimed that it solves the conflict between disparity, convergence, and accommodation. A non-digital video display was built way back in 1978: http://www.broadcastpapers.com/whitepapers/IBCDeMontfortCGContentfor3DTV.pdf

You're looking for an intuitive explanation of how this can "can trick the eye into accommodation of various physical distances"; however, note that your lack of insight in no way contradicts my claim, given the literature and hardware. But I'm feeling kind today so I'll give you a couple more hints. Your statement that "So the observer will always focus the eyes at a constant distance" betrays a deep ignorance of optics and physiology, namely that an unfocused image is mathematically equivalent to the focused image convolved with a 2D PSF (point spread function) based on lens parameters, and that the eye's accommodation response is driven in part by vergence and in part by an internal estimate of defocus based on 2D image analysis. The second hint that should help you sort out your internal confusion is the very term "integral imaging"; each microlens is a sort of holo-pixel (see diagrams on wiki). Focusing your eye on a plane will result in an image with a spatially varying amount of defocus because of the image encoding; accommodation will refocus the eye in such a way that a different set of viewing rays will be integrated into each projected visible element on your retina, until the right convolution effect is achieved to undo the image encoding+microlens defocus. It's the same when images are refocused with deconvolution in computational photography.

http://en.wikipedia.org/wiki/Integral_imaging: "Indeed, it has been demonstrated that an integral image can very accurately reproduce the wavefront that emanated from the original photographed or computer-generated subject, much like a hologram, but without the need for lasers to create the image; see Fig. 2. This allows the eyes to accommodate (focus) on foreground and background elements, something not possible with lenticular or barrier strip methods."

http://www.broadcastpapers.com/whitepapers/IBCDeMontfortCGContentfor3DTV.pdf: "The perceived advantages of integral imaging are that only a single aperture camera is needed to capture the 3D data. In addition the display is a full 3D optical model, the model is correctly scaled throughout the image space, and in viewing accommodation and convergence occur naturally thereby preventing possible eyestrain."

A prototype microlens array based flat panel video (as in, non-static) display was built by Hitachi in 2006, and they claimed that it solves the conflict between disparity, convergence, and accommodation. A non-digital video display was built way back in 1978: http://www.broadcastpapers.com/whitepapers/IBCDeMontfortCGContentfor3DTV.pdf

You're looking for an intuitive explanation of how this can "can trick the eye into accommodation of various physical distances"; however, note that your lack of insight in no way contradicts my claim, given the literature and hardware. But I'm feeling kind today so I'll give you a couple more hints. Your statement that "So the observer will always focus the eyes at a constant distance" betrays a deep ignorance of optics and physiology, namely that an unfocused image is mathematically equivalent to the focused image convolved with a 2D PSF (point spread function) based on lens parameters, and that the eye's accommodation response is driven in part by vergence and in part by an internal estimate of defocus based on 2D image analysis. The second hint that should help you sort out your internal confusion is the very term "integral imaging"; each microlens is a sort of holo-pixel (see diagrams on wiki). Focusing your eye on a plane will result in an image with a spatially varying amount of defocus because of the image encoding; accommodation will refocus the eye in such a way that a different set of viewing rays will be integrated into each projected visible element on your retina, until the right convolution effect is achieved to undo the image encoding+microlens defocus. It's the same when images are refocused with deconvolution in computational photography.

http://www.broadcastpapers.com/whitepapers/Content %20Technology-05-2006-046-048.pdf

The Thompson system for watermarking video and there's also a Fraunhofer Institute system:

http://www.pcworld.com/article/id,124676-page,1/ar ticle.html

These are all good ideas IMHO. As long as

1. The watermark isn't easy to remove
2. There is uncertainty as to whether the mark is removed
3. It isn't used to apply DRM

1 is obvious, 2 is there because the pirate has to be uncertain if their copy still has the idea, and 3. because the advantages of the system over DRM are lost if they use it for DRM!

Imagine you can freely buy and use the media you use however you like, but if it shows up on p2p, the ID can be pulled and traced back to you.

Since the DRM doesn't work, (not a single piece of media has successfully been locked up by DRM yet, a 100% failure rate). And since the DRM is already so restrictive that it puts off genuine sales, and is causing competition problems as inter operation is non existent. Then watermarking scheme will take over.

This one, I'm not so keen on, since the watermark is too easy to remove compared to the more mathematical approaches. The key point of any watermark approach is the mark must be difficult to remove and there must be uncertainty that the mark has been successfully removed.

My 2 cents.

"since Sky will *never* release the details of their encryption to *anyone*"

This is true, NDS , who are contracted to provide sky with its encryption systems, have never (and most likely will never) release any details in any way regarding any part of the crypto. But, a number of details are known about the encryption scheme as gleaned from patent documents and the such:

Sky is using the videoguard encryption which (so I am told) uses an industry standard scrambling algorithm called the CSA. (see http://csa.irde.to/). The algorithm is known and if the keys are known, the stream can be (and has been) easily decrypted. This is where the problem lies - the encryption relies not on the complexity of the algorithm or in secure distribution of keys but instead the algorithm used to generate the keys (done by your viewing card), as this is much more suited to a many-to-one service, such as content distribution. The key generation algorithm uses a closed and extremely complex algorithm and although the keys can be intercepted, they are practically impossible to predict. So even if this key generation algorithm was cracked (rumours suggest that in the past it has been) the broadcaster could easily encrypt the streams using a new algorithm and new viewing cards issued quickly, thus preventing free tv to any wanabee hackers.

10 Billion dollars and 12years ?

And they still dont have a workable product.

I worked at (and designed the software for) Kingston Interactive Television where we developed an iDTV, VOD and Internet system in less than 2 years. The whole project cost less than 30m and that includes the MAN & DSLAM's for 30k installations and the actual installation in 10,000 home. We where the first to launch this anywhere in the world, it actually worked and not a MS-box in sight. It was all bases on ARM STB's, Sun Application Servers, NCube Video servers, Linux for Internet and Tanberg MPEG Transcoders.

" The Material eXchange Format (MXF) is an open file format targeted at the interchange of audio-visual material with associated data and metadata. It has been designed and implemented with the aim of improving file based interoperability between servers, workstations and other content creation devices. These improvements should result in improved workflows and result in more efficient working than is possible with today's mixed and proprietary file formats." -- What is MXF

I used to work for Kingston Interactive Television which delivers real Interactive Digital Television and true Video on Demand within a wall garden of managed content and high speed Internet Access via IP on ADSL.

The technology works and has done for years, KIT was the first to commercially launch in 1999 and like others it had been running technology trials of Video over POTS for about 6 years previously.

There is little doubt that the platform blows the competing options out the water. DSL based DTV services cost about one tenth that of pure cable system since they doesn't require a fresh dig. They are also truly interactive instead of the faked-out client side interactions of satellite systems. It also offer a realatively pain-free experience of the internet for most ordinary consumers.

The problem is the incumbents who tend to have the content deals stitched up with the studios/distubutors.

Read more here : Kingston Case Study

The DVD is already compressed. DVDs are just MPEG2s at 720x480 (if NTSC). For more info see here and here.
190MB/minute is uncompressed 1080p HDTV (without audio). I doubt it will ever be delivered uncompressed.

The DVD is already compressed. DVDs are just MPEG2s at 720x480 (if NTSC). For more info see here and here.
190MB/minute is uncompressed 1080p HDTV (without audio). I doubt it will ever be delivered uncompressed.

I don't see any of the UWB promoters giving me enough information to support their claims. Very well, I'll fill in some of the blanks I admittedly left:

1. What is COFDM?

Coded orthogonal frequency division multiplex. It splits the information on many (typically thousands) or carriers. Basically you take a bunch of bits to form a symbol. FFT that (kind of) to get the amplitude of each carrier, and transmit. To receive: modulate down to baseband, inverse FFT. Well, actually that's OFDM. COFDM modifies the output bits before modulation so the carriers are less susceptible to multipath. See this paper on OFDM/COFDM

2. What kind of bandwidth, range can I get out of it?

Pretty much any, depending on how you pick the number of carriers, bandwidth, signal strength, and carrier coding. In digital audio/video broadcast, it goes 2 - 68km, at 5 - 32mbit, using just 8MHz of bandwidth. See this paper

3. Why isn't the industry pushing COFDM?

They don't need to. Digital Video and Digital Audio broadcast in the UK and (I think) some of Europe already uses COFDM. 802.11a already uses OFDM (it's only short range so you don't need the multipath protection). Everyone (except the US digital broadcast people, much to their disadvantage) already recognises it as "the thing to use".

4. How expensive is it to integrate COFDM onto a small device, such as a PDA?

Depends on the bandwidth and whether you offload all of the modulation into hardware or some in software. You've probably seen articles about Microsoft wanting to push processing of wireless lans into software (article). I haven't got any figures and I probably wouldn't be able to find any without NDAs. My ball-park guess would be from no milliwatts for 10kbit+, to 100mW+ for 1mbit+.

5. What's the spacial capacity?

Depends on choice of number of carriers, carrier modulation scheme, error correction etc. There's probably theoretical limits, but it's very versatile.

6. How much power does it use?

Ditto. It's not very suitable for very low power (milliwatt) devices - you're better off with bluetooth then. You can get lower power by reducing the number of carriers, error correction, etc which also lowers your data rate. I have no idea which uses less power. UWB will certainly use up a fair bit of power with its high speed pulse train. Still, you'd probably use something simpler like bluetooth in really low power low data rate devices anyway.

As far as spatial capacity goes, it's not at all an indicator of whether one technology is better than another. It says only whether you can get that data rate at the maximum distance you require. So for short range usage, all of your examples will work. What's important then is power vs data rate. I can't say any more as to which is more suitable because I don't have a figure for ODFM, PSK and all the other reasonable existing technologies, nor do I have one for UWB. It would be hard to give a definite figure anyway - it would depend on assuming a particular implementation is optimal.

This service (I'm the Software Architect), have launched the worlds largest Video on Demand over IP.

We have been doing this for two year now, I keep submitted links, each time we have a development, but slashdot have never seen fit to publish.

Some links:

"Kingston Interactive TV

Financial Times

Kingston Communications

Video Server Case Study

BBC joing broadband television platform

This case study reveals more details about the platform.

I just wish TV was available via FTP.

Well CmdrTaco, as a famous sycophant once said 'your wish is my command' :)

This system (for which I'm the Software Architect) offers interactive digital TV via IP, this case study
reveals all the gory technical details of the disruptive technology that is going to bring Microsoft down, by bringing IP to every home in the developed world in the next five years.