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Z2 pc digital vs av hdcp

Discussion in 'Projectors, Screens & Video Processors' started by buns, Jan 1, 2004.

  1. buns

    buns
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    AVF, not the best AV forum in the UK
     

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  2. buns

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    then the luminance plot...... note earlier that i assume this is so far wrong because of the use of PAL settings with an NTSC source
     

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  3. buns

    buns
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    now here is the RGB plot for the av hdcp with absolutely nothing changed. Clearly it is green as i had thought...... it definitely looks very different to the former plot which was the pc digital.
     

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  4. buns

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    then finally, the luminance plot using av hdcp. I havent seen the two side by side until i post this, so i dont know whether you can tell. However, the hdcp was a much brighter image than the pc digital.
     

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  5. buns

    buns
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    Right,

    I have an explanation (possibly). In service of pc digital, it is adjusting 'dvi'. I had assumed this would be the same for both pc digital and av hdcp. Well, it is and it isnt. Whilst my settings 1-3 and 10-12 replicate across from dvi to hdcp, the settings of 7-9 do NOT. When you consider that, the differences in the plots are quite acceptable.

    I adjusted both these modes so that the gains/bias/gamma were all the same and have redone to show better the difference..... so here they come.
     

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  6. buns

    buns
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    then the av hdcp (last one was pc digital)
     

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  7. buns

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    then the luminance plots were fairly similar for both.This shape, im told, is characteristic of the contrast being too high (note it is at default).

    The hdcp does look although it is a tad more red for the same settings. I guess it is possible that skin tones are in that 50 ish ire range, hence it would be unsurprising that they appeared relatively red. Were this the case, it would explain why the guys with measurements say red to be limiting and why those using just eyes have that feeling of warmth..... someone would need to check this out mind you.

    Now to recalibrate to NTSC using AVIA and then catch a film :D

    any thoughts from those who were interested by this question?

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  8. Quatermass

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    Quite possibly I will now talk a load of rubbish but……isn’t the video mid-grey temperature for the “pc standard” and for the “video standard” different? Could the shifts that you have recorded have been caused by the Z2 adapting in order to take account of the different standards for pc and video mid-grey temperature?
     
  9. buns

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    ok..... i dont know about the mid grey.....

    i know that video goes on a scale 16-235 and rgb is 0-255.... so that in mind, i basically assumed the only difference would be at the extremes, ie. if you send it an rgb signal from 235-255 and it expects video..... then it would be crushed so there should be a distinct flattening at the high (and low) IRE range.... I didnt think there should have been any differences

    In any case, were it done right, the temperatures should be identical in the mid IRE..... this is almost the definition of it being well calibrated. I could understand horizontal shift, but what we see is more like a vertical one

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  10. Quatermass

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    I think I need to do some more research! :)
     
  11. buns

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    you could be right..... you probably know just as well as i do! Alot of what i say i derived from what i have available...... i could have done so wrongly

    Actually I have ordered a book about all of this..... seems to have alot of the fundamentals there..... something like HDTV: pictures,panels and pixels..... or something along those lines.

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