How much quality loss if sending video through receiver?

Discussion in 'Beginners, General Questions' started by Nick B, Jan 6, 2004.

  1. Nick B

    Nick B Stunt Coordinator

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    I would very thankful for the input of forum members on this question: How much signal quality does one really lose if sending video through your receiver instead of directly to TV? In case it is relevant, I have a Denon 3803 A/V receiver, a JVC Progressive Scan DVD player and a Toshiba HD RPTV. What say you all on the convenience/optimal picture trade-off? As usual, all of your opinions are greatly appreciated.

    Nick
     
  2. Kevin*Ha

    Kevin*Ha Agent

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    I'm also interested in this. I'm color-blind so my opinion on the picture is taken with a grain of salt. Before I decide on going through the receiver I'd like to hear what others think.
     
  3. Ernest Yee

    Ernest Yee Supporting Actor

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    If you have good decent quality cables - like anything other than the $.50 pack of cables that comes w/ the receiver or dvd player - the loss will be very minimal. As in, you probably can't tell the difference.
     
  4. John S

    John S Producer

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    I run HD through 50mhz bandwidth component switching, I see no difference switched or direct to the tv.
    I think the Denon3803 is rated at 100mhz, should be able to handle anything.
     
  5. Chu Gai

    Chu Gai Lead Actor

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    To determine if the receiver or other switching device is capable of passing a video signal without visible degradation one generally refers to the rule of 3. Determine the frequency of the signal you're passing and multiply by 3. If the value is the same or less than the bandwidth of the device, it's suitable to be used for switching purposes. Let's take regular old DVD. That's 6.75 MHz. Multiplied by 3, that's about 20 MHz. So if your receiver has a 50 MHz bandwidth, you're all set. Simple, right?
     
  6. Ted Lee

    Ted Lee Lead Actor

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  7. Bob McElfresh

    Bob McElfresh Producer

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    It's based on the type of video signal you are sending through the reciever.

    I think the numbers for video are something like this:

    480i = 4.2 Mhz
    480p = 11.5 Mhz
    720p = 26.0 Mhz
    1080i = 26.0 Mhz

    This is why Yamaha calls their recievers "HD Compatible" with a 100 Mhz bandwidth. They use a 4 times factor, not 3.
     
  8. Chu Gai

    Chu Gai Lead Actor

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    I think you meant 36 MHz (or 37 MHz) for the 1080i Bob. For further clarification, when they say something like the receiver has a 100 MHz bandwidth, what they're saying is that the signal is 3 dB down (1/2 strength) @100MHz. Kind of equivalent to putting in a 2 way splitter.
     
  9. Doug_H

    Doug_H Supporting Actor

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    Your ability to detect problems is also dependent on your system. I have found I am unhappy with even a 100mhz switch when I play DVD's or HD on my FP. I stepped up to a $149 box
    http://www.inday.com/rgb4x/rgb4x.htm that carries 230mhz and there was a world of difference.

    I use the old 100 mhz in the bedroom where I see no problems on my 36" and my old JVC 50 mhz is in another room with a small TV and I see no problems in there.

    The bigger you go the more likely small problems will show up during heavy motion/action. I found the worst offending scenes are where a cloudy sky appears in the background. Using a lower bandwidth switch always caused artifacts or grain in the sky scene. The better switch removed them completely. On a small set I doubt I could have seen a difference.
     
  10. Chu Gai

    Chu Gai Lead Actor

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    For some reason it doesn't surprise me Doug. I sometimes wonder just how accurate the values actually are compared to the manufacturer's specs. Recall what the other switch box was by any chance?
     
  11. Nick B

    Nick B Stunt Coordinator

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    Thank you for your replies. John S is correct. The Denon 3803 is rated at 100mhz. So it sounds as though there will be little to no compromise of the signal quality if I route through the receiver. Unless I am missing something.
     
  12. Doug_H

    Doug_H Supporting Actor

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    Chu

    I will check when I get home. I believe it is an AVS but I am need to make sure.
     
  13. Bob McElfresh

    Bob McElfresh Producer

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    You have just given the correct answer to all of these weekly asked questions:

    "Do I really need this $xxx video cable?"
    "Will running video through my reciever cause problems?"
    "Do I really need these two $200 speaker wires?"
    "How much difference would I see moving from SVideo to Component?"


    It all depends on the 'sensitivity' of the equipment. Televisions have a screen-size which are a good indicator of sensitivity. Speakers .. are a bit more difficult to quantify.

    Kudos to Doug for reminding us of this basic concept.
     
  14. Ted Lee

    Ted Lee Lead Actor

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    question regarding that zektor article. i'm not sure i get which spec i'm supposed to be looking at? if i'm reading it right, it states for a 1080i signal, it needs a bandwidth of 111MHz?

    i don't think i've seen too many receivers with that kind of bandwidth? since my yamaha does "Component Signal DC-60MHz, -3dB" - does that mean i'm out of luck?
     
  15. Chu Gai

    Chu Gai Lead Actor

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    Allen Jayne, who also posts here, has a nice website chock full of useful information.

    That's a typo on that website you gave Bob, which by the way is also useful. If we take 111 and divide it by 3, we get 37 MHz, the bandwidth of 1080.

    Ted, why don't you update your contribution to the primer and include some of the info here? It'd be good to have it all in a convenient place.
     
  16. Ted Lee

    Ted Lee Lead Actor

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    chu - i'm honored you think i know what i'm doing, but i'm not clear on this stuff myself. [​IMG]

    i nominate bob! [​IMG] besides, he's got that fancy green moniker next to his name ... may be easier for him. [​IMG]
     
  17. Chu Gai

    Chu Gai Lead Actor

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    Hey you wrote it, you update it!! The 3x thing is a well known engineering rule of thumb, so I sure as hell can't take credit for it.
     
  18. Bob McElfresh

    Bob McElfresh Producer

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    The 3X is a 'fudge factor'/overhead that engineers like to have. I actually prefer a 4X in the specs for coax.

    The web site includes another link to how the calculations are done to calculate the bandwidth. I have not studdied it.

    But - Did we lose anybody? This is the Basics area so if you dont understand what we are talking about, please ask.

    (Chu, Ted and I are old friends discussing this stuff. Dont be afraid to chime in.)
     

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