How much quality is lost in video when using a switcher?

Discussion in 'Archived Threads 2001-2004' started by Josef_K, Dec 26, 2001.

  1. Josef_K

    Josef_K Agent

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    If im using a component switch how much quality is lost compared to me hooking the component cables directly to the TV?
     
  2. dougW

    dougW Stunt Coordinator

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    Josef, look for "Broadcast Quality" video to have minimal signal loss or to have the signal as close as it was when it entered the device, no matter what is doing the switching.

    Most low to mid-fi receivers do not offer broadcast quality. Flagship models, very well might. Other examples, are higher end pre-pros.

    So, long story short, to avoid potential signal loss, direct to output device is best-

    Lex
     
  3. jeff peterson

    jeff peterson Supporting Actor

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    Another thing to keep in mind are the video cables.

    Direct from source to monitor requires only one high quality cable. Source to receiver to monitor requires two. If you're paying a lot for the cable, double the price causes an "ouch" (in my wallet anyway).
     
  4. Allan Jayne

    Allan Jayne Cinematographer

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    Like a cable, a switcher or the switching circuits inside a receiver possess bandwidth, crosstalk, and impedance.
    Sometimes these figures are published, usually not. Sometimes only a descriptive term such as "HDTV quality" is used.
    For regular interlaced video, probably anything will do. For 480p you need 13 MHz bandwidth, for HDTV you need 37 MHz, for 1080i you can get away with about 22 MHz with today's TV sets.
    I don't know the recommended crosstalk numbers expressed as minus so many dB. The greater the minus, the better. Crosstalk causes color smearing and ghosting. Impedance mismatch (needs to be 75 ohms) can also cause ghosting.
    There is no easy way of proving the quality other than testing it yourself or taking someone's word for it.
    More on bandwidth:
    http://members.aol.com/ajaynejr/bandwid.htm
     
  5. John Tillman

    John Tillman Supporting Actor

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  6. Ron Boster

    Ron Boster Screenwriter

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    If you do a search you should find a discussion about this topic here and at www.avsforum.com (under HT General). Both discussions included people that deal with switchers in their everyday work enviroment. The one (among others) that they said caused no discernable loss of picture was extron.
     
  7. Glenn Overholt

    Glenn Overholt Producer

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    Josef - Everybody is assuming that you are talking about running component signals through A/V receivers for switching, but you can get a ZERO signal losss for $13. Just buy a standard composite A/V switcher from any electronics/discount store.

    Glenn
     
  8. Marty Neudel

    Marty Neudel Stunt Coordinator

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    >Just buy a standard composite A/V switche

    Glenn,

    actually, you'll need 3 switches; and there will be some loss, typically no more than 1 or 2 dB.

    Marty
     
  9. Allan Jayne

    Allan Jayne Cinematographer

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    Some contributors to this forum have reported good results using just one (non-powered, non-remote control) A/V switcher, connect the Y cable to the yellow jack, the Pr cable to the red jack, and the Pb cable to the white jack.

    Compare the picture quality with direct connection to the TV.

    If you really want to do experiments, try this: Connect DVD player Y output to switcher video input. Connect switcher video output to switcher left audio input. Connect left output to right input. Connect right output to TV component video green input jack. Compare (black and white rendition of) 200 TVL AVIA test pattern with that seen connecting just the Y cable direct from DVD player to TV. If the difference is hardly noticeable then the switcher will do an excellent job.

    (Do not use the audio jacks on a receiver for component video.)
     

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