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HDMI Input on CRT-RPTV- Always a Good Thing?

Discussion in 'Displays' started by James Edward, Jul 3, 2005.

  1. James Edward

    James Edward Supporting Actor

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    I have just ordered a Mits WS-65815. It has an HDMI input, so I purchased a Sony NS975 for video. The Sony seems well regarded for its digital output.

    I did some searches and see conflicting information as to whether HDMI is suitable for CRT-RPTV's. I thought I had read that CRT's converted the incoming RGB signal to digital, then back to analog. If so, I would think that HDMI input would prevent one conversion in the signal, and therefore be a good thing.

    Also... Even if it does not work this way, would the 975 player still be a good thing, since the digital output is a 1080i signal? But on the other hand, it's not a true 1080i signal, just upconverted.

    So... Would a 1080i HDMI upconverted signal beat a 480p RGB connection on this set?

    Any thoughts? Thank you for any replies.
     
  2. EricRWem

    EricRWem Screenwriter

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    Yes. [​IMG]
     
  3. alan halvorson

    alan halvorson Cinematographer

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    The main advantage to having a HDMI input is that it's HDCP compatible; you want that to future proof your display. I have often wondered how HDMI equiped CRT RPs could exist since the de-crypted HDCP bitstream must be converted to an analog signal which some pirate could tap and record and defeat the main purpose of HDCP encryption. I even posted a thread a while back that asked about this, but I never got a satisfactory answer.

    But, more to your point - you always want to keep the number of conversions to a minimum and the HDMI input reduces the number to one.
     
  4. Kirk Patrick

    Kirk Patrick Stunt Coordinator

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    i was under the impression that there is no analog conversion which is why it's protected

    it leaves the dvd in a digital stream and is displayed bit for bit on the tv via hdmi (this would apply to a digital set)...on an analog set, the digital stream would be converted to analog as it's final conversion

    i believe all the interest in the lg dvd player that upconverts via component is related to this issue...

    most upconverting players will only send the upconverted signal over dvi/hdmi to prevent piracy, this is mandated by fcc??

    but canada has no such rules and this you can buy the lg dvd player which will upconvert and send over component which IS an analog signal and can thus be pirated

    someone correct me where i am mistaken
     
  5. alan halvorson

    alan halvorson Cinematographer

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    Well, that's what I said. After the bitstream has been converted to analog, it's no longer protected and thru vulnerable. How do CRT RPs get away with this analog conversion when scalers and dvd players can't? I've never gotten a good answer.
     
  6. jim.vaccaro

    jim.vaccaro Second Unit

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    I think you misunderstand digital streams and digital devices. The bitstream has to be converted to analog SOMEHOW for you to see it, whether or not the TV is a CRT TV or not is irrelevent. Just like a CD has to be converted to analog SOMEWHERE for you to hear it (whether your CD player does the conversion with its internal DACs or your receiver does it, it happens.)

    Analog TVs, however, are totally incapabable of receiving a digital signal...that's why they're analog. No analog set out there has an HDMI port.
     
  7. alan halvorson

    alan halvorson Cinematographer

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    I don't know where you've been looking, but I find this Toshiba CRT RP and this Toshiba CRT RP with HDMI inputs. There are others. Are Best Buy and Buy.Com providing false information? I have never actually shopped for a RP and haven't visually confirmed that these or any sets actually have the claimed HDMI inputs, but I'll wager Best Buy and Buy.Com ain't lyin'.

    I realize that CRT RPs are analog and cannot use a digital bitstream directly, but that doesn't prevent them from including digital inputs and circuitry to do a digital to analog conversion. My question still is, how is that analog signal protected? If it is at all. I'll concede that tapping into a CRT RP may not be the best way to steal a HD signal, but it seems possible to me and a loophole I'm surprised Hollywood allowed.
     
  8. jim.vaccaro

    jim.vaccaro Second Unit

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    Whatever gave you the idea that these are analog sets? Just because they are CRT sets doesn't make them analog. These are HDTV sets, and most definitely digital as they can receive a digital signal.

    Analog only sets can't receive digital signals....that's what makes them analog.

    Any digital signal has to be converted to analog before human beings can see and/or hear it. A digital stream is nothing but 1's and 0's....that has to be converted into picture and sound somehow.
     
  9. alan halvorson

    alan halvorson Cinematographer

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    Well, that's a new one on me, Jim. Can you give me an example of this all-digital-no-analog CRT? I'm willing to be corrected, but I need more than someone's say-so. My long-time impression is that a RP is basically just a FP in a box with a mirror. In the professional world they're called Retros. All CRT FPs are analog, therefore, all CRT RPs are analog. Maybe I'm wrong, but someone, please, show me that I'm wrong. I don't want to go through life appearing more ignorant than I already am.
     
  10. jim.vaccaro

    jim.vaccaro Second Unit

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    Big Edit.

    OK, I see where you are coming from here...I think. You are talking about digital display tech, like DLP? I was thinking a digital TV is a TV that can receive and decode digital content. An analog TV can only receive analog content. CRTs can't display digital content without converting to analog, is that what you are saying?
     
  11. Kirk Patrick

    Kirk Patrick Stunt Coordinator

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    a dac (digital to analog converter) is part of every modern audio and video device, at some point a digital bistream is "read" by a converter and output as an unprotected audio or video signal, this is what we he hear or see, this signal

    in the case of rp-crt you have a dac that sends a signal to 3 color guns which display a projected image inside a box or on a screen

    in the case of an lcd or dlp, you have a digital bitstream that activates a pixel and diplays a color value, this is the picture we see

    so, three color guns create an image or pixels in an lcd screen create an image...both images are derived from a digital bitstream

    dac's are not all created equal and the "quality" of their conversion varies

    if you convert to analog, then back to digital, then back to analog again you have a progressive loss of signal quality with each conversion

    with hdmi to hdmi signals you have a digital bitstream that undergoes only one conversion, at the end, where it is converted to either digital/pixel/color values or red blue yellow values for cathode ray tubes

    as to the issue of protection, once the signal is converted to analog at the end stage it is certainly not protected from analog copying (via vcr eg.) but is presumably protected from digital copying _bit for bit_ i assume that the analog image could be recorded by a dvd recorder which would be a digital recording but not a _bit for bit_ recording which would be the equivalent of a pristine master, which is what the studios are afraid of

    i am partly explaining this to myself so please correct where i am in error
     
  12. alan halvorson

    alan halvorson Cinematographer

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    Looks like you have it right Kirk; a pirate will not be able to be do a bit-for-bit recording and must accept another the very small quality loss due to a analog-to-digital conversion. However, I can't imagine he'd care about that because now he has a high-def, unencrypted copy that's still excellent.
     

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