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 Post subject: Technical Information & Specifications
PostPosted: 12 Oct 2011, 20:02 
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So, for some systems such as PAL+, technical information is readily available. Others, such as red-blue anaglyph 3D, are just obvious. I thought a thread with information on the less well known systems might be useful. I have some technical papers on MUSE Hi-Vision LD, & the two different types of HDVS discs, so I'll start with that.
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 Post subject: MUSE Hi-Vision LD, part 1
PostPosted: 12 Oct 2011, 20:42 
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There were actually multiple iterations of MUSE optical videodiscs before the final consumer product was developed. The goal was to have 30 minutes per side playback time in CAV mode, or 60 minutes in CLV, the same as standard NTSC LD, but this was difficult to achieve. The MUSE signal has a bandwidth of 8.1 MHz, as opposed to 4~5 MHz for NTSC or PAL, meaning that the carrier frequency has to be higher, and the recorded bandpass wider.

The first prototype MUSE LD system was developed in 1984. (That's right, kids, before the first Digital Audio LDs were released!) At that time, the MUSE system was still under development, but it was recognized that packaged media would be important to the introduction of HDTV. The early MUSE system used a carrier-multiplex form of digital audio which was incompatible with LD recording, so a different type of multiplex was used on the disc, and processing was necessary in the player to change it back into the form accepted by the MUSE decoder. As a result, audio was limited to two channels of 32 kHz sampled 10-bit companded PCM.

The carrier frequency used was 14 MHz, with deviation of ±2 MHz, ie, black level at 12 MHz, white level at 16 MHz. The same emphasis used for broadcasting was applied. A second signal was also recorded, a "pilot tone" at a frequency of 2.28 MHz (67.5 times the line frequency) & an amplitude of -20 dB relative to the video carrier. This provided a reference for synchronization & to drive the moving-mirror tangential servo, so that jitter could be reduced to below 10 ns without the use of a digital time-base corrector.

The track pitch of the disc was 1.65 micron, and the minimum linear playing speed was 18 meters per second. The inner recorded radius in CAV mode was 95 millimeters, giving a play time of 17 minutes at the conventional 1800 revolutions per minute. In CLV mode, the inner recorded radius was 55 mm, the speed varied from 3100 to 1200 RPM, & the playing time was 30 minutes.

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Information & illustration from "Optical Videodisc for High-Definition Television by the MUSE", Tateo Toyama et al, SMPTE Journal, January 1986, pp 25 et seq. (Paper originally presented at 19th Annual SMPTE Television Conference, 16 February 1985.)


Last edited by publius on 12 Oct 2011, 21:51, edited 1 time in total. _________________
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 Post subject: Re: MUSE Hi-Vision LD, part 2
PostPosted: 12 Oct 2011, 21:29 
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Supposedly there was an effort to develop a MUSE version of VHD, but this seems to have gone nowhere.

Sanyo continued working on the MUSE LD problem, & the MUSE encoding format itself continued to evolve. A second Sanyo system was similar to the first, with the same pilot tone frequency (aplitude -28 dB) & play time, but used a deviation of only ±1.5 MHz, so that the black & white level frequencies were 12.5 & 15.5 MHz. This system again multiplexed 32 kHz, 14-10 bit companded 2-channel audio data into the MUSE signal, and also added a CD-type audio track, for a total of 4 channels. ("Hi-Vision Optical Video Disc", Toshiaki Hioki et al, IEEE Transactions on Consumer Electronics, vol 34 no 1, February 1988, pp 72 et seq.)

By 1991, Sanyo had developed a disc with 60 minutes of play time per side. This used a pickup with a lens numerical aperture of 0.6 and a newly-developed laser diode with a wavelength of 670 nanometers (as opposed to 0.5 and 780 nm for NTSC players), providing a smaller scanning-spot size. This allowed reducing the linear velocity to 14 m/s, and the track pitch to 1.12 microns. The carrier frequency and deviation were changed to 13±1.5 MHz. The MUSE signal, which by that time had been finalized (daily broadcasts began in that same year), was used without alteration, and the CD-type audio signal was multiplexed at -27 dB. Thus, a total of 6 audio channels was available, four from the MUSE A-mode audio signal, & 2 from the Red Book track. ("High Density Muse Videodisc", Hitoshi Terasaki et al, IEEE Transactions on Consumer Electronics, vol 37 no 3, August 1991.)
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 Post subject: Re: Technical Information & Specifications
PostPosted: 12 Oct 2011, 21:51 
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At this point, other consumer electronics manufacturers became involved. A consortium of five firms, including Sanyo and Pioneer, was formed in September 1991 to develop & market the Hi-Vision LD format, & Pioneer introduced the HLD-V500 commercial player based on this format in May 1992.

The carrier frequency of the final format was 12.5 MHz, with deviation ±1.9 MHz, or a frequency range of 10.6—14.4 MHz. The pilot signal of 2.28 MHz was used, as before, and the Red Book CD-audio track was allowed as an option but not required. The inner playback radius was 55 mm in CLV, with a starting rotational speed of 2700 RPM, and 76 mm in (1800 RPM) CAV, with a track pitch of 1.1 micron, providing 60 or 30 minutes per side respectively (20 or 10 minutes on a 20 cm disc, although I have never heard of one). In order to deal with dropouts, the error correction code in the MUSE audio signal was changed from BCH(82,74) to BCH(82,67). (The extra bits were taken from those set aside for "independent data" in the MUSE specification.) These codes are closely related, & it is believed that all consumer MUSE decoders can accept both types of audio signal. A 76-bit control and address signal was inserted, using biphase modulation at 2.7 megabaud, in line 564 of each frame, which is left blank and reserved in the MUSE specification for exactly such uses.

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Information & illustration from "MUSE Videodisc System", Takashi Sakakibara, 1993 NAB HDTV World Conference Proceedings, pp 147 et seq.
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 Post subject: Re: Technical Information & Specifications
PostPosted: 13 Oct 2011, 02:53 
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I know how fast my 5" CDV spin in the player, so when I first read Muse LD spin up to 2700 rpm for a 12" disc (and not all discs are perfectly flat) the players must have a serious disc clamp.
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 Post subject: Re: Technical Information & Specifications
PostPosted: 13 Oct 2011, 15:20 
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The foregoing is easier to understand if a few basic facts about optical disc recording are kept in mind.

The smaller the scanning spot, or the greater the linear speed with which it scans down the track, the higher the frequency which can be reproduced. Linear speed depends on the rotational speed and the playback radius ; obviously, for a given length of track on the disc, the higher the speed, the shorter the play time. Scanning spot size is determined by the laws of optics, and decreases as the wavelength gets shorter, or as a characteristic of the lens called "numerical aperture" increases. Beyond a certain point, however, increases in NA have little effect, because of the imperfections of real optical systems. A smaller spot size not only allows a higher frequency to be detected at the same linear speed, it allows the track-to-track spacing to be reduced, so that a greater length of track, & thus a greater playing time, can be provided on the same size disc.

For frequency modulation, Carson's Rule indicates that the minimum bandwidth for undistorted transmission is equal to the total frequency deviation, or swing of the carrier around its unmodulated frequency, plus twice the bandwidth of the signal to be transmitted (16.2 MHz in the case of the 8.1 MHz MUSE signal). The greater the deviation, the higher the signal-to-noise ratio after demodulation, for a given carrier-to-noise ratio. On the other hand, in optical recording, for a given spot size & linear speed, the lower the carrier frequency, the higher the carrier-to-noise ratio. And, finally, the carrier frequency has to be at least 1.5 times the bandwidth of the modulating signal.

So, some of these factors are in competition, while others work together. The final system had a lower carrier frequency and a wider deviation than its predecessors, giving it a higher signal-to-noise ratio. It used a smaller scanning spot, so its linear speed could be lower, giving a smaller inner playback radius (in CAV) or slower initial rotation speed (in CLV), and the track spacing could be narrower, thus making its playback time longer. This gave it the potential to be a successful consumer product, although market conditions did not allow that potential to be fully realized.
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 Post subject: Re: Technical Information & Specifications
PostPosted: 05 Jan 2012, 06:15 
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publius wrote:
So, for some systems such as PAL+, technical information is readily available. Others, such as red-blue anaglyph 3D, are just obvious. I thought a thread with information on the less well known systems might be useful. I have some technical papers on MUSE Hi-Vision LD, & the two different types of HDVS discs, so I'll start with that.


What exactly is PAL+? I haven't found anything on it. Is it like PAL 60?

STAY AWESOME! :)
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 Post subject: Re: Technical Information & Specifications
PostPosted: 05 Jan 2012, 06:51 
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cessnaace wrote:
What exactly is PAL+? I haven't found anything on it. Is it like PAL 60?

STAY AWESOME! :)

PAL+ is an "augmentation" system for widescreen broadcasting. A standard PAL image is broadcast, with a 16:9 aspect-ratio image letterboxed into the 4:3 aspect-ratio frame. In the black bars at top & bottom, the chrominance subcarrier is modulated (at black level) with information relating to the vertical resolution. A PAL+ decoder takes this information & uses it to interpolate the 432 "picture" lines of the letterboxed image to 576, which is the full number of visible lines in PAL, giving a 16:9 aspect-ratio full-frame image.

In practice, it didn't work quite as desired. For one thing, distortion or interference in the "helper" signal would mess the reconstruction process up.
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 Post subject: Re: Technical Information & Specifications
PostPosted: 05 Jan 2012, 10:47 
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We had quite a bunch of PALplus broadcasts here in .de on the state owned channels.
It was around the time when 16:9 crt TV's became more common, so maybe from around 1996 or so.
I wonder when exactly it was they gave up on that system.
I could imagine it was long before they switched to HD broadcast.
And the other oddity is, those channels broadcast HD in 720p50 these days. (ARD and ZDF that is).
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 Post subject: Re: Technical Information & Specifications
PostPosted: 05 Jan 2012, 17:36 
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publius wrote:
cessnaace wrote:
What exactly is PAL+? I haven't found anything on it. Is it like PAL 60?

STAY AWESOME! :)

PAL+ is an "augmentation" system for widescreen broadcasting. A standard PAL image is broadcast, with a 16:9 aspect-ratio image letterboxed into the 4:3 aspect-ratio frame. In the black bars at top & bottom, the chrominance subcarrier is modulated (at black level) with information relating to the vertical resolution. A PAL+ decoder takes this information & uses it to interpolate the 432 "picture" lines of the letterboxed image to 576, which is the full number of visible lines in PAL, giving a 16:9 aspect-ratio full-frame image.

In practice, it didn't work quite as desired. For one thing, distortion or interference in the "helper" signal would mess the reconstruction process up.


Thanks for the info!

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 Post subject: Re: Technical Information & Specifications
PostPosted: 18 Feb 2012, 04:36 
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Here's an excerpt from the HIL-C2EX user's manual, showing the frequency allocations for MUSE & NTSC LDs at the bottom, & a table of the different types of disc the player will accept (as well as what discs it won't). I have some service literature which indicates that Sony used a 20 cm MUSE test disc, but it would seem that none was marketed to the public — pity.

Incidentally, according to this manual, frame numbers of up to 61 000 can be assigned on a CAV Hi-Vision LD, which potentially adds more than 3 minutes of play time per side over the standard NTSC type (54 000 frames).


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 Post subject: Re: Technical Information & Specifications
PostPosted: 07 Jul 2012, 01:45 
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publius wrote:
... & the two different types of HDVS discs, so I'll start with that.


I could not find any information about Sony's HDVS laserdiscs, can you please explain?
(I tried to put one into my Pioneer CLD-D925 player, and it aborted with error "P5").
  
 
 Post subject: Re: Technical Information & Specifications
PostPosted: 07 Jul 2012, 03:21 
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algoviano wrote:
I could not find any information about Sony's HDVS laserdiscs, can you please explain?
(I tried to put one into my Pioneer CLD-D925 player, and it aborted with error "P5").

Where did you obtain a HDVS disc? I've been looking for one for a long time!

The Sony "baseband" Hi-Vision videodisc, made for playback by the HDL-2000 player (or, later, the HDL-5800 recorder/player), stores an analog high-definition video without MUSE bandwidth compression. These machines used the same infrared laser as standard LD players. In order to obtain sufficient bandwidth for the signal, 20 MHz for luminance & 6 MHz for chrominance (line-sequential), the recording is divided into two tracks. Half the lines of the picture are recorded on the first track, & the other half on the second track. The lines are also shuffled around to reduce the effect of dropouts. Chrominance is line-sequential, & time-division multiplexing with time-compression is used for chrominance & luminance, so the bandwidth per track is about 12 MHz. Audio is digital, 48 kHz, 16 bits, 2 channels, with the data embedded into the video signal in the form of a burst at the beginning of each line (similar to the colour burst on NTSC or PAL).

The playback mechanism resembles (in fact, was based on) the three-beam pickup used in conventional LD players, but where the central beam normally reads the track of data pits, & the two side beams are used for tracking, in the HDL-2000 the two side beams read the parallel signal tracks, while the center beam is used to keep them in line. In order to make this work, the power ratios of the diffraction grating are changed from 2:11:2 for LD, to 3:2:3.

FM carrier frequency is 16.3 MHz at 50% grey level, with the very narrow deviation of 1.74 MHz between white & black levels (±870 kHz). Track spacing is 1.5 microns between "paired" tracks, & 1.7 micron between "unpaired" tracks, so the average value is the 1.6 micron of conventional LD. Inner recorded radius of the CAV disc is 98.1 mm, with a play time of 8.4 minutes ; inner recorded radius of the CLV disc is 67.2 mm, with a rotational speed of 2630 rpm, giving a linear velocity of 18.5 m/s, & a play time of 15 minutes. Outer recorded radius is 146 mm.


So, your CLD-D925 is not going to read this disc. Firstly, the inner recorded radius is too far out, so the pickup does not see a laser recording. Secondly, if it did somehow pick up one of the tracks, it would have a hard time making sense out of 562 or 563 lines per revolution, & a digital audio burst instead of a colour burst.
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 Post subject: Re: Technical Information & Specifications
PostPosted: 07 Jul 2012, 12:03 
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publius wrote:
Where did you obtain a HDVS disc? I've been looking for one for a long time!

Thank you very much for your information about HDVS!

I got my HDVS disc from a friend who got it from a friend etc. ... and neither of them is a "laserdisc freak". I am very happy that it finally found its way to me, because I am interested in such "oddities" and besides regular laserdiscs and LD players have got also some TED, CED, VHD ... (discs, not players). In the internet there is much false information around, especially if the object is little known, so I am always happy to get something like this into my hand to be able to see for myself. By the way: my HDVS disc was actually "hidden" inside a wrong cover - a normal LD cover. I don't have the original HDVS cover.

On my CAV disc "HDP-2000" (Title "HDL-2000 demonstration disc") there is a 9mm wide ring (from radius 51mm to radius 60mm) that looks shiny like the recorded area, but without visible field separations, maybe it is of some value to the HDVS player at start time. The real recorded area shows visible field separations (CAV) under certain lighting condition, and contains two zones, one from radius 96mm to radius 114mm and the other from radius 114mm up to radius 146mm. I have no idea why these two zones look different in the reflection. Maybe only one of the zones is really recorded and the other one is "empty"?

First I thought that the inner "shiny ring" could contain something to inform a regular LD player that this is not a regular LD, but when I saw the reaction of my Pioneer CLD-D925, it was clear that this is not the case. The Pioneer actually did not only show error "P5", but also stopped reacting afterwards. I had to power off the unit several times until I could make the EJECT work again ...

Do you also know from when until when the HDVS discs were sold by Sony?
Also I am confused e.g. by the Sony HIL-1000 player: in the "UK Laserdisc Archive" I can see, that in the back it has got terminals to connect it to a MUSE decoder, but in the front I can see that it has got the HDVS logo on it. Can it do both the MUSE Hi-Vision Laserdisc and the HDVS format, or what??
  
 
 Post subject: Re: Technical Information & Specifications
PostPosted: 07 Jul 2012, 16:56 
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algoviano wrote:
I got my HDVS disc from a friend who got it from a friend etc. ... and neither of them is a "laserdisc freak". I am very happy that it finally found its way to me, because I am interested in such "oddities" and besides regular laserdiscs and LD players have got also some TED, CED, VHD ... (discs, not players).
I quite understand about liking oddities.

algoviano wrote:
On my CAV disc "HDP-2000" (Title "HDL-2000 demonstration disc") there is a 9mm wide ring (from radius 51mm to radius 60mm) that looks shiny like the recorded area, but without visible field separations, maybe it is of some value to the HDVS player at start time.
I have observed something similar on CAV MUSE discs. I believe this band is recorded according to the CLV inner-radius specifications ; in case the player searches for the CLV inner radius first, this band ensures that it will recognize that a valid disc is present, & is encoded with information to instruct the player that the disc is in CAV.

algoviano wrote:
The real recorded area shows visible field separations (CAV) under certain lighting condition, and contains two zones, one from radius 96mm to radius 114mm and the other from radius 114mm up to radius 146mm. I have no idea why these two zones look different in the reflection. Maybe only one of the zones is really recorded and the other one is "empty"?
I have been able to distinguish differences in program content on CAV discs. On test discs, for example, it is sometimes possible to tell which test patterns are recorded in which bands. Without knowing anything of the contents of the disc, or its run-time, it is hard to say what is going on there.

algoviano wrote:
Do you also know from when until when the HDVS discs were sold by Sony?
So far as I know, they were first produced in 1989 or 1990, & continued in production until sometime after 1995. It is hard to say, because information I have collected suggests that most were 'custom' pressings. LDDb lists release dates into 2000, but based on what information I do not know.

algoviano wrote:
Also I am confused e.g. by the Sony HIL-1000 player: in the "UK Laserdisc Archive" I can see, that in the back it has got terminals to connect it to a MUSE decoder, but in the front I can see that it has got the HDVS logo on it. Can it do both the MUSE Hi-Vision Laserdisc and the HDVS format, or what??
The confusion here comes from the fact that Sony used the term HDVS for the whole "High Definition Video System", including consumer as well as professional equipment. So, for instance, the MST-2000 MUSE decoder has the HDVS logo, & Sony HDTVs likewise. But we speak of the studio-format discs for the HDL-2000 as "HDVS discs" for lack of anything better to call them.
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 Post subject: Re: Technical Information & Specifications
PostPosted: 07 Jul 2012, 22:31 
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Thanks again for your fast and competent answer! :-)

publius wrote:
... Inner recorded radius of the CAV disc is 98.1 mm, with a play time of 8.4 minutes ; inner recorded radius of the CLV disc is 67.2 mm, with a rotational speed of 2630 rpm, giving a linear velocity of 18.5 m/s, & a play time of 15 minutes. Outer recorded radius is 146 mm.

Did you calculate the speed of 18.5 m/s or was it written somewhere in your technical documentation? I am asking, because I measured something between 96.0mm and 96.5mm as innermost radius of the recorded area of the CAV disc (not 98.1mm), and together with 2630 rpm this would calculate to a minimal speed of only 18.2 m/s.

In case of a CLV disc you mentioned 2630 rpm - is the speed afterwards gradually reduced or does it happen in several distinct steps? What is the minimal rotational speed on the outside of a 30cm HDVS CLV disc? By calculation with 18.5 m/s it should be around 1767 rpm, if calculated with 18.2 m/s it should be only 1729 rpm. Which one is correct?

I am looking forward to my scheduled travel to Japan (in August). When I will be there I want to find out whether laser discs are still sold in some second-hand and junk shops as it was a few years ago. Also I am still looking for a MUSE disc ...
  
 
 Post subject: Re: Technical Information & Specifications
PostPosted: 08 Jul 2012, 21:15 
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algoviano wrote:
Did you calculate the speed of 18.5 m/s or was it written somewhere in your technical documentation? I am asking, because I measured something between 96.0mm and 96.5mm as innermost radius of the recorded area of the CAV disc (not 98.1mm), and together with 2630 rpm this would calculate to a minimal speed of only 18.2 m/s.

In case of a CLV disc you mentioned 2630 rpm - is the speed afterwards gradually reduced or does it happen in several distinct steps? What is the minimal rotational speed on the outside of a 30cm HDVS CLV disc? By calculation with 18.5 m/s it should be around 1767 rpm, if calculated with 18.2 m/s it should be only 1729 rpm. Which one is correct?
The figures as I gave them are taken from a paper, Optical Disc System for Wideband High Definition Video Signal, published in the IEEE Transactions on Consumer Electronics for 1989 August. My HDL-2000 owner's manual gives the rotational speed for CLV discs as "approximately" 2600 RPM at the inner circumference, & 1200 RPM at the outer circumference. At 18.5 m/s & an outer radius of 146 mm, I get a rotational rate of 1210 RPM by calculation, which agrees. Whether Sony used a "true" CLV, or CAA (stepwise, but with small steps), as used on most LaserDiscs by 1989 or so, I have no way of knowing.
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 Post subject: Re: Technical Information & Specifications
PostPosted: 09 Jul 2012, 03:11 
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publius wrote:
The figures as I gave them are taken from a paper, Optical Disc System for Wideband High Definition Video Signal, published in the IEEE Transactions on Consumer Electronics for 1989 August. My HDL-2000 owner's manual gives the rotational speed for CLV discs as "approximately" 2600 RPM at the inner circumference, & 1200 RPM at the outer circumference. At 18.5 m/s & an outer radius of 146 mm, I get a rotational rate of 1210 RPM by calculation, which agrees.

Thank you for your help! Now I see that I miscalculated something in my last posting, using wrongly the innermost radius of CAV instead of CLV in my calculation.

With 2600 rpm at radius 67.2mm and 1200 rpm at radius 146mm the resulting linear speed is actually in both cases around 18.3 m/s. And with an innermost radius of 97mm for CAV the linear speed at 1800 rpm again is 18.3 m/s. Now everything fits. :-)

The numbers given in the owner's manual are more reliable than those in the IEEE papers, because the latter are written in an early stage of the development with only prototypes around, and the ones in the user manual are written later when the product is finalized. Especially if it is a one-company-only product such as HDVS videodiscs.

I understood that the HDVS videodisc uses two parallel tracks at the same time, but how is the information splitted between these two tracks? And are the chrominance and luminance signals separately recorded, or combined in form of a composite video signal as it is in the "normal" laserdiscs?
  
 
 Post subject: Re: Technical Information & Specifications
PostPosted: 09 Jul 2012, 04:40 
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Of course, you may have to allow for "lead-in" & "lead-out" tracks which do not contain valid picture information, but allow the player to get synced up & locked in.

The chroma is time-compressed (4:1, from 6 MHz to 24), & then inserted into each line before the luminance signal (which is time-compressed to a smaller degree, 24:20 or 6:5), in a way similar to MAC or in fact MUSE. I suppose I was not clear enough before in my description of the encoding ; unfortunately, the forum settings will not allow me to attach the paper to this post ("The extension pdf is not allowed"). So that you can see for yourself how it works, I have captured an image which shows the most important details. I have to say that I am not sure what they did about the fact that there is an odd number of lines per frame.


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File comment: pages 209 & 210, showing the time-compressed encoding & line-permutation
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 Post subject: Re: Technical Information & Specifications
PostPosted: 09 Jul 2012, 05:05 
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publius wrote:
Of course, you may have to allow for "lead-in" & "lead-out" tracks which do not contain valid picture information, but allow the player to get synced up & locked in.

The chroma is time-compressed (4:1, from 6 MHz to 24), & then inserted into each line before the luminance signal (which is time-compressed to a smaller degree, 24:20 or 6:5), in a way similar to MAC or in fact MUSE. I suppose I was not clear enough before in my description of the encoding ; unfortunately, the forum settings will not allow me to attach the paper to this post ("The extension pdf is not allowed"). So that you can see for yourself how it works, I have captured an image which shows the most important details. I have to say that I am not sure what they did about the fact that there is an odd number of lines per frame.

You could put it in a .zip, that's what I do here.
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